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Dinosaur Database

This database will eventually contain thousands of pictures and illustrations of mesozoic dinosaurs. At the moment it contains a few hundred entries. I will post more as I find the data. It will also be integrated with google maps to allow geographical searches and browsing.

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	Classification:CLASS	Name:acanthodii	Age:
	Locality:	Size:	Fossil Name:
	Notes:The acanthodians - commonly known as the "spiny sharks" - are the earliestknown vertebrates with jaws. These structures are presumed to have evolved from the first gill arch of some ancestral jawless fish which had a gill skeleton made of pieces of jointed cartilage (see p. 20). The popular name "spiny sharks" is really a misnomer for these early jawed fishes. The name was coined because they were generally shark-shaped, with a streamlined body, paired fins and a strongly upturned tail-, stout bony spines supported all the fins except the tail - hence, "spiny sharks." In fact, acanthodians were a much earlier group of fishes than sharks. They evolved in the sea at the beginning of the Silurian period, some 50 million years before the first sharks appeared (see pp. 26-29). Later the acanthodians colonized freshwaters, and thrived in the rivers and lakes during the Devonian and in the coal swamps of the Carboniferous. But the first bony fishes were already showing their potential to dominate the waters of the world, and their competition proved too much for the spiny sharks, which died out in the Permian. Many paleontologists consider that the acanthodians were close to the ancestors of the bony fishes. Although their internal skeletons were made of cartilage, a bonelike material had developed in the skins of these fishes, in the form of closely fitting scales. Some scales were greatly enlarged, and formed a bony covering on top of the head and over the lower shoulder girdle. Others formed a bony flap over the gill openings (the operculum in later bony fishes).
	Classification:CLASS	Name:agnatha	Age:
	Locality:	Size:	Fossil Name:
	Notes:The first vertebrates to evolve were the agnathans, or "jawless fishes." Their traces are found in rocks of the Late Cambrian period, more than 520 million years old. These first fishes had no jaws in which to seize and manipulate prey. Nor did they have paired fins, to stabilize their bodies in the water. Catching prey and eating it therefore presented problems; consequently, these fishes were all small (rarely more than 1 ft/30 cm long), and restricted to either sucking up microscopic food particles from the mud of the seabed, or feeding on plankton in the surface waters. Agnathans had no bone in their bodies. The internal skeleton was made entirely of gristle or cartilage. Unlike bone, this material decays. So the only way that paleontologists know these ancient fishes existed is because their bodies had an "overcoat" of bone. This consisted of a large bony shield that covered the head, and small bony scales that covered the body. This armor plating was the only protection these small, jawless fishes had against attack by the large, predatory sea scorpions that also lived in these Paleozoic seas. The bony armor has been preserved in the rocks, and gives the fossil agnathans their collective name of ostracoderms, meaning "shell-skins." Despite their lack of jaws, ostracoderms dominated the seas and freshwaters of the northern hemisphere for about 130 million years, from Early Ordovician to Late Devonian times. Two distinct lines evolved (see pp. 18-19) - the pteraspidomorphs (the heterostracans and theloclontids), and cephalaspidomorphs (the osteostracans and anaspids). Only 2 types of agnathan survive today. Neither has the bony armor of their ancestors, and both are highly specialized, mainly marine fishes - the wormlike, scavenging hagfishes and the eel-like, parasitic lampreys.
	Classification:CLASS	Name:chondrichthyes	Age:
	Locality:	Size:	Fossil Name:
	Notes:What could be more evocative of "jaws" than sharks? In fact, sharks and their relatives - the skates and rays, and the chimaeras or ratfishes - were among the earliest vertebrates to develop jaws and bony teeth (see p. 20). These jawed fishes also share another feature, All have skeletons made entirely of gristle or cartilage, which unites them as the chondrichthyans, or car, tilaginous fishes. (Agnathans also have cartilaginous skeletons, but they, of course, have no jaws.) The skeleton is "calcified," or strengthened by prismatic granules of calcium carbonate de, posited in the outer layers of the car, tilage. These granules are arranged in an unmistakable mosaic pattern, unique to these cartilaginous fishes. Finally, a thin layer of bone covers the cartilage. Cartilaginous fishes share other char, acteristics. For example, their fins are paired, and stiffened by horny rays of cartilage. The pelvic fins in males are modified into penislike "claspers," to aid in the transfer of sperm during copulation - a feature unique to these cartilaginous fishes. The skin bristles with tiny, teethlike scales, which give it a rough texture like sandpaper. (In fact, 19th,century cabinet-makers used shark skin, called "shagreen, to give a smooth finish to the wood.) Like the teeth, the body scales are constantly replaced throughout the fish's life. Two main groups of cartilaginous fishes evolved from a common ancestor during the Early Devonian period, some 400 million years ago (see pp. 18-19). Representatives of both groups - the elasmobranchs and the holocephalians - survive today, distinguished by their teeth and quite different feeding habits.
	Classification:CLASS	Name:placcidermi	Age:
	Locality:	Size:	Fossil Name:
	Notes:The placoderms, or "flat-plated skins," were a strange assemblage of heavily armored jawed fishes. Several large, interlocking plates formed a bony head shield, while another series of plates encased the front part of the body in a trunk shield. The rest of the body was usually naked, with no scaly covering. The placoderms represent a specialized offshoot from the main evolutionary line leading to the bony fishes (see pp. 18-19). A comparatively short, lived group, they first appeared in the Early Devonian and had died out by the Early Carboniferous. Many placoderms spent their lives on the seabed, their flattened bodies weighed down with heavy bony armor. Others had less armor and became swimmers in the open sea. The jaws of all these fishes were equipped with broad dental plates, rather than indiv, idual teeth, for crushing hard-shelled prey. Representatives from the 4 main groups of placoderm (rhenanids, ptyctodonticls, arthrodires and anti, archs) are described.
	Classification:FAMILY	Name:adapidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The lemurlike adapids were abundant in Eocene times, but then declined, becoming extinct in the Late Miocene about 10 million years ago. They were mostly European, but some lived in Asia and North America. Adapids had several features that were a distinct advance on those of the plesiadapids. Their backs were more supple, which increased their mobility in trees, as did their longer, more flexible limbs (whose digits bore nails rather than claws) and grasping big toes and thumbs. They had shorter snouts, with eyes that had moved round closer to the front of the face. Their brains, too, were relatively larger. Although it is possible that adapids could only cling and leap, it seems likely that they were advanced enough to walk and run on top of branches. The lemurlike adapids and lemurids (below) are sometimes grouped together as the strepsirhini ("twisted noses") becuase their moist noses are divided vertically and laterally by slits.
	Classification:FAMILY	Name:allosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Allosaurs were similar in build to megalosaurs, but even larger. They were the largest carnosaurs around during Late Jurassic times, and lumbered through every continent in the world. But they were soon to be rivaled by even bigger creatures - the tyrannosaurs of the Cretaceous (see pp. 118-121).
	Classification:FAMILY	Name:amynodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Amynodonts were a short lived Eocene and Oligocene group of about 10 genera of hippopotamuslike, probably am, phibious, animals with large bodies and short stout limbs. Among the features which suggest a semi-aquatic lifestyle are the presence in some genera of prehensile lips and tusks. Canines were short or absent in the 2 other rhinoceros families, but in the amynodontids they were huge, curved, and continually-growing. It seems likely then that amynodontids took the place in this habitat of the aquatic pantodonts such as Coryphodon, and were themselves eventually replaced by the aquatic rhinoceroses of the more advanced rhinocerotid family, such as Teleoceras.
	Classification:FAMILY	Name:anchisauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family comprises the earliest prosauropods, which were among the first dinosaurs to appear. They were all fairly small (less than 10 ft/3 in in length), with long, lightly built bodies, slim limbs, small heads and long necks and tails. Anchisaurs seem to represent an early experiment in plant-eating among dinosaurs. Their teeth were cylindrical and blunt, with filelike serrations along the edges - like the teeth of some modern herbivorous lizards. The arms were only slightly shorter than the legs, which suggests that the animal probably spent much of its time on all-fours. This stance would make it easier to reach plants growing at ground level. But the ankle joint was strong and well developed, too, indicating that the animal could also stand up on its hindlegs, and use its hands to pluck off higher vegetation. Some paleontologists believe that anchisaur-type prosauropods may have been the ancestors of the bird-hipped dinosaurs, the ornithischians (see pp. 134-169). Certain features of Anchisaurus (below), in particular, seem similar. Its long, slender neck, the structure of its shoulders and forelimbs, and details of its hip bones and ankle joints - all these structures are similar to those of some of the early ornithopods, such as Heterodontosaurus (see p. 136). The round, blunt teeth suggest that Anchisaurus ate plants. Ferns and horsetails flourished in damp places at the time, and conifers and palmlike cycads grew in drier, upland areas. But all planteaters, including modern ones, need a larger digestive system than meat-eaters, since tough, fibrous plant material takes longer to break down than flesh. So, a capacious stomach and long intestines would have been found in Anchisaurus' long body, accommodated in front of the hips. This mass of innards would have unbalanced a 2-legged animal, so, it is argued, Anchisaurus and its relatives had to take up a 4-legged stance most of the time for stability. All the continents of today's world were fused together into one great landmass in Jurassic times, some 200 million years ago, when Anchisaurus was alive. To find its remains in such divergent places as the eastern seaboard of North America and in southern Africa is therefore not surprising, and is further evidence for the theory of plate tectonics (see pp. 10-11).
	Classification:FAMILY	Name:ankylosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family of armored dinosaurs became abundant toward the end of the Cretaceous period, and largely replaced tlieir relatives, the nodosaurs, in western North America and East Asia. Like the nodosaurs, they were heavily armored on the back with thick plates and spikes. But the head armor was more extensively developed, and there was a unique weapon at the tip of their tails. This was a large ball of fused bone, which could be swung like a club from side to side with potentially lethal effect on an attacking carnosaur. These ankylosaurs were built like military tanks, and some species were about the same size. They were shorter and stockier than the nodosaurs, with massive-boned hips and hindlegs to support the heavy, clubbed tail. The hips were fused to the backbone by at least 8 sacral vertebrae, forming a super-strong anchor for the hindquarters. The hip bones themselves had degenerated into a shapeless mass, with no obvious trace of the bird-like arrangement so characteristic of the ornithischian dinosaurs.
	Classification:FAMILY	Name:anoplotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This primitive group of artiodactyls has notoriously defied classification. It is possible its members are close to the camels.
	Classification:FAMILY	Name:anthracotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The anthracotheres or "coal beasts," named for the deposits in which many have been found, may be related to the hippopotamus family. They were basically an Old World group, with many members appearing in Asia from the Eocene right up to the Pleistocene. They also migrated to North America, where they are mainly found in Oligocene deposits. Like the hippopotamuses which many of them resemble, anthracotheres were probably chiefly aquatic animals. It is possible that one replaced the other in the same aquatic niche.
	Classification:FAMILY	Name:antilocapridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The pronghorn Antilocapra of North America is the only surviving genus of this family, but the Miocene and Pliocene saw the evolution of a large number of different types of antilocap, rids. The other ungulates that evolved in North America - the camels and the horses - spread across to Asia and to South America and became extinct in their homeland. The antilocaprids, on the other hand, remained in North America and spread nowhere else, although they were a very successful and varied group during the Pliocene and Pleistocene periods. Antilocaprid head ornamentation consisted of a horny sheath, usually branched, around an unbranched bony core. The sheath was shed annually but the core was retained. Most species had a single pair of horns, but others had as many as 5 or 6, and some were bizarre in shape. In the living pronghorn, males have longer horns, with forwardpointing prongs below backwardpointing hooked tips - hence the animal's common name. Although most of the even,toed ungulates have only 2 functional toes, the others being greatly reduced and not touching the ground, it is only in the pronghorns that all vestiges of the other toes finally disappeared, not even bony splints remaining. Their evolution of long, pointed hooves at the end of long, slender legs has enabled them to be fast runners, reaching speeds of up to 5 5 mph (86 km/h) when escaping from predators. Their hooves are cushioned against the shock of leaping up to 26 ft/8 in in a single stride.
	Classification:FAMILY	Name:arctocyonidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This is the earliest and most primitive family of the order, and may be close to the ancestors of the later hoofed animals. Arctocyonids were mostly short-limbed, rather clumsily-built animals, up to the size of small bears.
	Classification:FAMILY	Name:ardeosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The geckos were among the earliest of the modern groups of lizard to appear, in the Late Jurassic period. The only surviving family, the Gekkonidae, evolved relatively recently - in the Late Eocene, some 40 million years ago. It contains more than 670 species, which have spread throughout the warm tropical zones of the world.
	Classification:FAMILY	Name:argyrolagidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family consists of animals very similar to the kangaroo rats and jerboas of today, but are completely unrelated to them. Like such rodents they may have lived in deserts and been mostly nocturnal animals. They would have moved swiftly over the open ground by a series of prodigious leaps, and fed on the shoots and roots of desert plants.
	Classification:FAMILY	Name:astrapotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Because they were engulfed in volcanic ash, it has been possible to reconstruct many complete astrapotherfid skeletons. Yet their lifestyle and their relationship to the rest of the South America ungulates remains puzzling.
	Classification:FAMILY	Name:baryonychidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family was created in 1986 to cover one member - an oddity among theropods. A single skeleton was discovered in 1983 in Sussex, southern England; it had a peculiar skull and forelimbs, unlike those of any other dinosaur.
	Classification:FAMILY	Name:borhyaenidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family evolved from didelphid ancestors, and consists entirely of extinct carnivorous South American marsupials. Although completely unrelated to placental mammals of other continents, the borhyaenids evolved body shapes and lifestyles similar to those of cats, dogs, bears and other placental carnivores. This is a superb example of convergent evolution.
	Classification:FAMILY	Name:bovidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These are the true antelopes and the cattle. The head ornamentation of both males and females consists of bony horn cores covered with true horn that is not shed annually. The bovids evolved in the Old World in Miocene times about 20 million years ago. The earliest fossils, of gazellelike bovids, have been found in France, the Sahara and Mongolia. By the Late Miocene, about 10 million years ago, there was a huge increase in bovid variety, with 70 new genera appearing. By the Pleistocene, there were more than 100 genera, about twice as many as exist today. Bovids are grazing animals, with highcrowned teeth adapted for chewing grass. Their lifestyle contrasts with most of the other even-toed ungulates, which feed on soft leaves. They were restricted to the Old World until as recently as the Mid Pleistocene, about I million years ago, when they migrated across the Bering land bridge that existed at the time to reach North America. There they survive today as bison, bighorn sheep and mountain goats. The vast majority of bovids, however, still live in the Old World, occupying a great range of habitats from forests and grasslands to swamps and even deserts.
	Classification:FAMILY	Name:brachicisauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family were the giants of the sauropod group. They ranged through North America, Europe and eastern Africa during Mid-Jurassic to Early Cretaceous times. All had a similar structure - small heads perched on extra-long necks, deep bodies and shortish tails. They differed from all other sauropods in having their front legs longer than their hindlegs, so that the body sloped down from the shoulders, like that of a modern giraffe. Until recently, the brachiosaurs could claim to have had among their members not only the most massive dinosaur ever to have lived, but also the largest creature ever to have walked on land. This was Brachiosaurus (below). But recent finds in North America show that there were even larger sauropods than Brachiosaurus. In the 1970s, massive bones from 2 sauropods were found in Colorado, and unofficially called Supersaurus and Ultrasaurus. Then, in 1986, even larger bones were unearthed in New Mexico, and provisionally named Seismosaurus. Some of the remains are enormous, and suggest lengths of more than' 100 ft/30 in. For example, there is a shoulder blade 8 ft/2.4 in long, and individual vertebrae 5 ft/ 1. 5 In long.
	Classification:FAMILY	Name:brontotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The third family of the suborder Hippomorpha consists of the "thunder beasts." This group of rhinoceroslike creatures evolved in the Early Eocene, about 50 million years ago, in North America and eastern Asia from small animals similar to the first horses. Although they existed for only about 15 million years, about 40 different types have been described. In some ways their evolutionary history parallels those of the uintatheres and arsinoitheres. All the brontotheres browsed on soft forest vegetation. Some forms evolved massive horns and large canines, and there was a common tendency to hugely increased bulk. These animals are sometimes known as titanotheres, another allusion to their great size. Although they are often referred to as "horns," brontothere head growths were not composed of, or even covered in, horn. Nor were they made of compacted hair, as are those of the rhinoceroses. In fact they were more like the ossicones of giraffes: bony structures with a covering of thick skin. Since these grotesque knobs were larger in the males than the females, they were possibly used for display, or perhaps as weapons during intra-species fights to determine the leadership of the herd. Shortly after the brontotheres reached the peak of their monstrous development, climates became dryer and more open woodlands became plentiful. Evolution favored more lightly-built animals that could graze and live on the plains. Brontotheres became extinct in the middle Oligocene and were replaced by the rhinoceroses.
	Classification:FAMILY	Name:cainotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This is one of the most primitive families of the suborder. As in most primitive members of any group, the caino, theres were generalized animals, with few features to hint at the more specialized members to come. Most were rabbitlike in size, appearance and in their bounding or leaping style of locomotion.
	Classification:FAMILY	Name:camarasauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family were much smaller than their contemporaries, the brachiosaurs and diplodocids. Their necks and tails were shorter, and their skulls were higher, with blunter snouts. The teeth, too, were quite different from those of other sauropods; they were long, spoon-shaped and forwardpointing. All these features suggest that the camarasaurs ate different plants from the larger sauropods in the locality, and so did not compete with them for food.
	Classification:FAMILY	Name:camelidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The modern camelids are found only where conditions are harsh. The camels are famed as "ships of the desert," capable of covering immense distances across difficult terrain in the most inhospitable of climates. Thanks to their extraordinary physiology, they can live for up to 2 months on rough grazing alone, without additional water, and can endure great changes of temperature. The South American camelids - the llamas and their relatives - are also found in challenging habitats, including that of the high Andes. Modern camels have evolved a whole array of adaptations for coping with hot, dry environments. Most other animals, including humans, lose water steadily in hot, dry weather by sweating, panting and breathing. As a result, their blood thickens, until eventually it circulates too slowly to remove heat from the body processes via the skin, and the animal suffers a sudden and dramatic rise in temperature which soon kills it. Camels avoid this danger by having unique blood that does not thicken, and because they economize on water loss in a variety of ways.
	Classification:FAMILY	Name:canidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The canids - including the modern foxes, jackals, coyotes, wolves and dogs - are a successful group of "allrounders." With an evolutionary history of some 40 million years, they have become adapted to a great range of habitats and a variety of diets. As members of the order Carnivora, they are related to the otters and weasels, cats and mongooses, and to the seals, sealions and walruses. First known from Late Eocene times, about 40 million years ago, the earliest canids were relatively short-legged animals that resembled mongooses and civets more than dogs. They were almost entirely restricted to North America, the center of canid evolution; the family did not colonize other continents until the end of the Miocene, as recently as 6 million years ago. From a mere 5 genera in the Early Oligocene (35 million years ago), the canids had diversified to 42 genera by the Late Miocene (10 to 6 million years ago), and have since declined to the 12 modern genera alive today, which includes the domestic dog. The teeth of canids have contributed much to their versatility of habitat and diet. As well as the large, pointed canines (the word canine simply means "doglike") and well-developed meatshearing (carnassial) teeth, they also possess powerful crushing molars at the back of the jaws. So they are omnivorous - eating anything from bones and flesh, to insects and fruit. Canids also evolved a superb sense of smell, good vision and acute hearing. Their long limbs and great stamina, combined with their style of running on the tips of their toes (called digitigrade locomotion), allow them to chase,swiftmoving prey for considerable diSiances. Intelligence and social living, as seen today in hyenas and wolves, also enhance their ability to catch prey, avoid predators, rear young successfully and colonize new habitats.
	Classification:FAMILY	Name:captorhinidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This successful group of primitive reptiles ranged throughout the Permian period, surviving for almost 40 million years before becoming extinct. They lived in Africa, Asia, India and North America. Primitive though the captorhinids were, they were more advanced than their protorothyridid ancestors (above). Their skulls were much stronger, with the braincase now firmly attached to the skull roof and cheeks, and the multiple rows of teeth in their jaws could deal with tough plants or hard-shelled animals.
	Classification:FAMILY	Name:ceratopidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The most abundant large herbivores of the Late Cretaceous period in western North America were the great horned dinosaurs of this family. They have been found nowhere else in the world. Exclusively 4-legged, these herbivores were well protected from attack by contemporary, bipedal carnosaurs, such as Tyrannosaurus and Albertosaurus (see pp. 118-121). Long, sharp horns grew from their massive heads, and a bony frill, developed from the rear skull bones, guarded their necks. The pillarlike legs, with their heavy, hoofed feet, supported a stocky body that was covered in thick hide, There was also safety in numbers, and the horned dinosaurs moved in great, foraging herds through the upland forests, chopping off vegetation with their sharp, toothless beaks. The family of horned dinosaurs is divided into 2 evolutionary lines. There were ceratopids with short neck frills and great horns on the snout. And there were ceratopids with long neck frills and great horns on the brow.
	Classification:FAMILY	Name:ceratosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family of megalosaur-type dinosaurs was characterized by a small horn on the snout. Contemporaries of the other large carnosaurs, they lived in North America and East Africa in Late Jurassic times. But their remains are rare in comparison to those of their relatives.
	Classification:FAMILY	Name:cervidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Although the cervids, or true deer, were quite late to evolve they have become the principal browsing animals of the Northern Hemisphere and South America. Their diet includes leaves, grass, twigs, bark and moss. A characteristic feature of all living cervids is the presence of antlers in the males (and in females of the reindeer Rangifer) of virtually all species. The exceptions are the hornless musk deer Moschus and Chinese water deer Hydropotes. Antlers are branched bony outgrowths of the head. They differ from the ornamentation of the other ruminants in that they are shed and regrown each year. They are readily distinguished from other head ornaments by the presence of a swollen "burr" at the point at which they are shed. Each year the antler, develops with another branch until a maximum for each species is reached. Cervids use their antlers chiefly in display or for ritual sparring rather than for actual fighting. The ultimate example of antler development is seen in the Pleistocene deer Megaloceros.
	Classification:FAMILY	Name:cetiosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The earliest sauropods lived worldwide during the Jurassic period and into the Cretaceous. Their name means "whale lizards," and refers to their great size, rather than to a water-dwelling lifestyle. Two primitive features remained in members of the cetiosaur family. First, their vertebrae were only partially hollowed out, so the body weight would have been considerable. And second, the hips were attached to the backbone by only 4 sacral vertebrae, a weaker arrangement than in later sauropods.
	Classification:FAMILY	Name:chalicotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Whereas the rest of the ungulates have hooves on their toes, these animals evolved large claws instead and evidently could not run. The dentition and other features of some of the advanced chalicotheres, such as Chalicotherium from the Miocene of Europe, suggests that they were forest browsers, and may have been able to rear up on their hind legs while feeding on the succulent leaves of trees and shrubs. Although fossil evidence is sparse, chalicotheres seem to have been a remarkably successful group, which flourished for almost 50 million years. Animals resembling chalicotheres appear as decorations on Siberian tombs dating from the 5th century BC. Also sightings periodically recur in Kenyan forests of the so-called Nandi bear, a creature whose stance is alleged to be gorillalike, with forelimbs longer than its hindlimbs, large bearlike claws, and with a horselike face. It is little wonder, then, that claims are made that chalicotheres still survive!
	Classification:FAMILY	Name:coeluridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The coelurids flourished worldwide from the Late Jurassic through to the Early Cretaceous. In lifestyle, they were similar to the podokesaurs - light, weight, active predators, running about on long legs, and grasping prey with their strong, clawed fingers. The number of fingers on each hand was reduced to 3.
	Classification:FAMILY	Name:compsognathidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:To date, there is only one known member of this family. It was a contemporary of the coelurids, and closely resembled them in structure and lifestyle.
	Classification:FAMILY	Name:coryphodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Coryphodonts are found within the Pantodonta, a diverse order of browsing animals that thrived in Paleocene and Eocene times from 60 million to 40 million years ago. In Asia, a few pantodonts did not become extinct until the Early Oligocene, some 35 million years ago. Though some were as small as rats, they were mostly bulky animals, some as large as rhinoceroses. They led a semi-aquatic lifestyle, feeding by rooting up tubers, roots and other vegetation.
	Classification:FAMILY	Name:cyamodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This group of placodonts had developed turtlelike shells on their backs. They evolved in the Mid-Triassic and survived to the end of that period. These shelled placodonts assumed a more completely aquatic lifestyle than Placodus (above), and began to look and behave like modern turtles, although they were unrelated - a phenomenon known as convergent evolution.
	Classification:FAMILY	Name:dasypodidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The armadillos first appeared in Argentina in Late Paleocene times, about 60 million years ago. By the Late Oligocene, some 30 million years ago, several forms had evolved the characteristic articulated armor seen in the armadillos, which are essentially very similar and are included in the same family. Armadillos have always remained restricted to the Americas: the 20 modern species are almost all found in South and Central America, though I has recently extended its range into the southern part of the United States.
	Classification:FAMILY	Name:desmatophocidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The desmatophocids were a family of primitive sealions. These carnivores are superficially similar to the seals of the family Phocidae, and show the same adaptations to the same way of life. The most obvious difference between the 2 groups is in the structure of their hindlimbs. Sealions, fur seals and walruses can turn the hind flippers forward to help them move on land something the true seals cannot do.
	Classification:FAMILY	Name:dichobunidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Dichobunids are a family of small, primitive animals which must have looked more like rabbits than ungulates. Also, their classification as eventoed ungulates might seem to be inappropriate, since many had 5 toes on each foot. However, features of the skeleton indicate that this was the group from which all the others evolved.
	Classification:FAMILY	Name:didolodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:It is not clear how this long-lived family should be classified. Some authorities place it with early rooting and browsing ungulates in the order Arctocyonia; others regard it as a litoptern. It is perhaps best considered as transitional between the two. The earliest fossils are found from the Paleocene, around 60 million years ago, with examples still being found in the Mid-Miocene, 50 million years later.
	Classification:FAMILY	Name:diplodocidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Diplodocids were sauropod dinosaurs with enormously long necks and even longer tails. Their bodies and limbs were slender, and their heads tiny. But despite their great length, these giant plant-eaters were lightweights in comparison to their relatives, the bulky brachiosaurs (see pp. 128-129). This was because the vertebrae of diplodocids had been reduced to a complex latticework of bony struts, designed to save weight, yet take maximum stress. The diplodocid family thrived worldwide during the Late Jurassic period and into the Cretaceous. But toward the end of that period, the group seems to have gone into decline, with only a few representatives restricted to eastern Asia.
	Classification:FAMILY	Name:diprotodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This major group of Australian marsupials includes mostly herbivorous animals. Diprotodonts have a single pair of lower incisors, which point forward. They have between I and 3 pairs of upper incisors, no canines, and a long gap (diastema) between their incisors and cheek teeth, as in rodents. The second and third toes of their hindfeet are greatly reduced in size and are bound within a single sheath of tissue - a specialization used for grooming. Living relatives of the diprotodonts include the familiar koalas and kangaroos, as well as the phalangers (Australian opossums) and wombats.
	Classification:FAMILY	Name:dromaeosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family must have been among the most fearsome predators of the Cretaceous period in North America and Asia. They are the only representatives of the Infraorder Deinonychosauria, the "terrible-clawed lizards," and structurally seem to have been an intermediate group of dinosaurs. They had the light, speedy body of a coelurosaur, and the large head of a carnosaur. Although they were no larger than many of the other meat-eaters around at the time, dromaeosaurs were formidable predators. They had a lethal weapon in the form of a large, sickle-shaped claw on the second toe of each foot. They were also armed with sharp, pointed teeth and clawed, grasping hands. They had large brains, and were intelligent enough to have hunted in packs.
	Classification:FAMILY	Name:elephantidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This is the family to which the modern elephants belong. They differ from their earlier relatives, the mastodonts, principally in the form of the teeth. True elephants have lost the tusks of the lower jaw, and this has enabled them to modify their method of mastication. Mastodonts ground their food in a complex rotary motion, whereas elephants cut or shear it. The change of action has also affected the teeth, which are taller, with longer, more complex enameled surfaces. In many species, there is only one grinding tooth at a time in each side, top and bottom. Each of these 4 teeth has a series of up to 20 transverse loops of wrinkled enamel, infilled with softer dentine and separated from each other by thin bands of cement. The whole grinding surface thus forms a large, nearly flat area of very hard phosphate which resists the wear from grinding siliceous grasses. Another tooth appears only when the earlier teeth have worn down. Several members of the family survived the end of the Ice Age but became extinct shortly after, some possibly as the result of being hunted by early humans. These extinct species include the Eurasian woodland elephant, Elephas antiquits; the dwarf forms, such as E. falconeri, which lived on the Mediterranean islands; and 2 mammoths, Mammuthus primigenius and M. jeffersoni. Their cousin, the American mastodont Mammut americanum, joined them in extinction at this time. Only 2 species survive today, the African and the Indian elephants.
	Classification:FAMILY	Name:enaliarctidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The enaliarctids were the earliest members of the otarioids to evolve, and were the ancestors of the modern sealions, fur seals and walruses. They lived during the Early Miocene, about 23 million years ago, and like the phocids, probably evolved from among the mustelids. Later in the Miocene, about 18 million years ago, enaliarctids gave rise to another extinct family of early seals, the desmatophocids. Later still, about 15 million years ago, some of the enaliarctids evolved into the odobenids, or walruses. Another branch, which evolved in the Middle Miocene about 13 million years ago, led to the otarfids, the sealions and fur seals.
	Classification:FAMILY	Name:entelodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These large piglike animals, which probably originated in Asia in the Late Eocene, became common in Europe and Asia, and spread into North America. They were most prolific in the Oligocene but some survived in North America until the early Miocene, about 20 million years ago. Some were massive, reaching the proportions of a hippopotamus. A prominent feature of the entelodontids was the presence of two pairs of bony knobs protruding from the side of the lower jaw.
	Classification:FAMILY	Name:equidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Equids have their origins in small, scampering animals, no larger than small terriers, which browsed in the forests of Early Eocene times. With the arrival of the generally drier climate of the Miocene, around 20 million years ago, humid forests began to give way to more open country, and in some parts of the world, notably in North America, to vast grassy plains. It is to such conditions that the modern equids horses, zebras and asses - are so well adapted.
	Classification:FAMILY	Name:esthonychidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Esthonychids are the sole family in the Order Tillodontia. They were once widespread across Paleocene and Eocene North America, eastern Asia and Europe. Tillodonts may have been related to the pantodonts or to arctocyonids, but their evolutionary relationships, and even their lifestyles, are unclear.
	Classification:FAMILY	Name:fabrosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The earliest-known ornithopods belong to this family and date back to the Early Jurassic period, some 200 million years ago. This was the heyday of the fabrosaurs, and they spread throughout the world. In appearance, they were small and lizardlike, but they ran upright on long, slender legs. Superficially, they looked like the small, carnivorous theropod dinosaurs - the coelurosaurs (see pp.106-109).
	Classification:FAMILY	Name:giraffidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Giraffes, like all other artiodactyls except the pigs and hippopotamuses (see pp. 266-269) are cud,chewers, or ruminants. There are no incisor teeth at the top of the jaw, instead the lower incisors work against a bony pad at the front of the mouth. Having ripped off foliage from bushes and trees, the animal chews and then swallows it for the first time. The food then passes into the rumen, the first chamber of a complex, 4chambered stomach, where it is fermented by microorganisms. Once the food is partially digested, it is returned to the mouth and chewed again before its second journey back down the entire alimentary tract. This method of digestion is very efficient at breaking down fibrous plant food, but the ruminant pays a price for this efficiency in that food takes a long time to pass through its gut, and it must spend a considerable proportion of each day chewing the cud. There are two modern giraffes, both living in Africa south of the Sahara. The more familiar is the tall, long,necked, long-legged giraffe Qiraffa of the African savannah, which feeds from the tops of thorn trees. The other is the smaller, darker okapi Okapia, at home in the gloom of the African tropical forest. With the exception of the camels, the ruminants typically have paired head ornaments. In the case of the giraffes these take the form of hornlike growths, called ossicones, which are covered in skin. Both the giraffe and the okapi are 2toed browsers, the family having evolved before the grazing ungulates developed. The fossil record reveals a number of different forms, most of which were quite unlike the 2 modern representatives of the family.
	Classification:FAMILY	Name:glyptodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The glyptodonts were gigantic, armadillolike creatures, which can be thought of as the mammalian equivalent of the heavily armored dinosaurs called ankylosaurs. Some 50 genera evolved from the Early Miocene, about 20 million years ago, reaching their peak of success on the grasslands of South America and southern North America during the Pliocene and Pleis, tocene, between about 5 million and 3 million years ago. They survived until historical times, and feature in the legends of Patagonian Indians. Glyptodonts were grazing animals, lacking teeth in the front of their mouths but having powerful grinding teeth at the back. They had massive, deep jaws with downward-pointing projections of their cheekbones, which provided a site for the attachment of the powerful muscles they needed to chew grasses and other tough vegetation. Some glyptodonts became very large: one of the biggest, Qlyptodon, which lived in Argentina during the Pleistocene, between 2 million and 15,000 years ago, was the size of a small automobile and as formidably armored as a military tank (5 ft/ 1. 5 m tall and 10 ft 6 in/3.3 m long). The glyptodonts evolved from armadillolike animals with armor arranged in rings. By the end of the Pliocene, about 2 million years ago, the armor had become fused to form a rigid bony dome-shaped "shell" made up of a mosaic of polygonal bony plates that enclosed the animal's back, a helmet above its skull, and a series of rings or a solid tube of bone around the tail. This armor accounted for 20 percent of the animal's weight (the tusks of an elephant account for 3 percent).
	Classification:FAMILY	Name:hadrosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The hadrosaurs were the most common, varied and well-adapted group of ornithopod dinosaurs - a real success story in the history of the ruling reptiles. The group probably evolved in central Asia, and by Late Cretaceous times had spread all over the lands of the northern hemisphere - migrating eastward into North America across the land bridge that existed at the time, and from there eastward again, into Europe. The southern landmass of Gondwanaland had, however, broken up by Late Cretaceous times, and the continents were drifting apart. No had, rosaurs have been found in Africa, India or Australia. But some obviously managed to reach South America, because the remains of a primitive, flat-headed hadrosaur, called Secernosaurus, were discovered in Late Cretaceous rocks in southern Argentina. These animals probably crossed over from North America via the chain of volcanic islands that existed where Central America now lies. Superficially, hadrosaurs looked quite different - with many variations of crests and bumps on their heads. But structurally, they were all the same. The most obvious feature that unites them as a group was the way the front of the face was elongated into a broad, flattened snout with a toothless beak. This beak looked rather like the bill of a modern duck, and it is this feature that has given the group its popular name of "duckbilled" dinosaurs. Although there were no teeth in the front of a hadrosaur's mouth, there were batteries of cheek teeth arranged in rows in the upper and lower jaws, with new teeth continually replacing old, worn ones (see Edmontosaurus, p. 149). This was a unique development among dinosaurs, and was probably a major factor in the success of the group. Another likely reason for the hadrosaurs' success was that the flowering plants (angiosperms) had evolved during Cretaceous times, and toward the end of that period had multiplied over all the earth's surface. So, besides plant foods such as ferns, horsetails, cycads and conifers, hadrosaurs could now add to their menus a profusion of flowering plants. The success of the hadrosaurs could well have been the reason for the decline of the other types of plant-eating dinosaurs - the iguanodonts and giant sauropods - which could not compete with the versatile newcomers. All hadrosaurs had long hindlegs and shorter forelegs, both equipped with hooflike nails for walking. They probably spent most of their time browsing on all-fours, but when they had to run away from predators, they would have reared up on hindlegs and sprinted away, balanced by their long tails. The hadrosaur family is divided into 2 distinct groups (subfamilies), according to the type of crest that grew on the head. Some animals had flat heads surmounted with solid, bony crests, while others had no crests at all. This group is called the hadrosaurine duckbills. They were the most successful, long-lived and wide-ranging members of the family, being among the last dinosaurs to survive. The second group of hadrosaurs had high, domed heads, surmounted by flamboyant, hollow crests. These are called the lambeosaurine duckbills (see pp. 151, 153). They seem to have evolved in North America, and been largely confined to that continent.
	Classification:FAMILY	Name:hegetotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Hegetotheriids include animals which are rabbitlike in form, mode of loco, motion, and lifestyle. Many had long hindlimbs which would have enabled them to lope in the characteristic way.
	Classification:FAMILY	Name:helaletidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:One of the earliest families of tapirs, the helaletids were much like today's species, but were smaller and more lightly built.
	Classification:FAMILY	Name:henodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These armored placodonts evolved in the Late Triassic period. The similarity to turtles, first developed among the cyamodonts (above), was brought to an extreme in members of this family. They had developed a great, bony shell that covered their backs and undersides, and they had lost most of their teeth, replacing them with a horny beak like that of a modern turtle.
	Classification:FAMILY	Name:heterodontosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family looked like fabrosaurs, but their teeth were quite different. In fact, the dental arrangement was unique among dinosaurs, and indeed among most other reptiles. Heterodontosaurs were among the first dinosaurs to have developed cheeks, to retain food within the mouth (above). They also had 3 kinds of teeth in their jaws, and each performed a different function (see Heterodontosaurus, below). The family's name reflects this feature - "varied-toothed lizards."
	Classification:FAMILY	Name:hippopotamidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The hippopotamus family is a recent group dating from the Late Miocene. They may have evolved from the anthracotheres, whose niche as swampliving rooters they probably took over, or possibly from fossil peccaries. The name of the family comes from the Greek for "river horse." Most were probably semi-aquatic, but some, like the living pygmy hippopotamus, were forest dwellers. The only other living species is the almost entirely aquatic H. amphibius.
	Classification:FAMILY	Name:homalodotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:A characteristic feature of the homalodotheriids is the presence of clawed toes. This is highly reminiscent of the chalicotheres of the Old World and North America.
	Classification:FAMILY	Name:hyaenidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The hyenas, also members of the order Carnivora, appeared only relatively recently, in Mid-Miocene times, about 15 million years ago. They probably evolved on the African continent, and then spread throughout the Old World. The only hyena known from the New World is Chasmaporthetes, which lived in North America during the Pleistocene. It also lived throughout Africa, Asia and Europe. It was a fast-running hunter rather than a scavenger, and its legs and teeth were similar to those of the modern cheetah. Indeed, in Africa it had to compete with the true cheetahs, which also lived there during Pleistocene times. The role of "mammalian scavenger" in North America was played chiefly by the heavy-toothed borophagine dogs, such as Osteoborus. Their diet and lifestyle mirrored that of the hyenas elsewhere in the world. Today, hyenas are restricted to the warmer areas of Africa and Asia. Although they are chiefly scavengers, they are also agile and intelligent hunters, running in packs to bring down swift-footed grazing mammals. They have heavy bone-crushing teeth, and their remarkably tough digestive system enables them to absorb the organic matter in bone, while indigestible bone fragments, hooves, horns, ligaments and hair are regurgitated as pellets.
	Classification:FAMILY	Name:hypsilophodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Hypsilophodonts were the "gazelles" of the dinosaur world. They probably lived in social herds, like modern deer, and would have been continually alert. When danger threatened - and there were many carnivorous dinosaurs around to attack them - they sprinted off at high speed, their lightweight bodies and long, running legs facilitating a fast retreat. Hypsilophodonts were among the most successful of the dinosaurs. As a group they flourished for about 100 million years, from the Late Jurassic to the end of the Cretaceous, and spread to every continent in the world except Asia. They are also an important group in the evolution of the dinosaurs. Paleontologists believe that the hypsilophodonts gave rise to 2 other major groups of ornithopods - the iguanodonts (see pp. 142-145) and the "duckbills" or hadrosaurs (see pp. 146-153). The herbivorous lifestyle of hypsilophodonts was similar to that of the fabrosaurs, the group of earlier Jurassic ornithopods that became extinct at about the time the hypsilophodonts began their rise (see p. 136). In fact, some paleontologists believe that the fabrosaurs were the direct ancestors of the hypsilophodonts. Structurally, the fabrosaurs and hypsilophodonts were also similar. But the hypsilophodonts had several anatomical modifications. For example, they had developed the retaining cheeks that prevented the food from falling out of the sides of the mouth. And their upper and lower teeth met, or occluded, as regular rows, rather than interlocking alternately as those of fabrosaurs.' This arrangement would have given a better chewing and grinding surface. The hips of hypsilophodonts were also more advanced than those of the fabrosaurs. Part of the pubis bone (known as the prepubic process) projected forward, and provided an extra area to which the leg muscles could attach (see pp. 104-105). This resulted in greater running power. But this extra bone was small enough to leave room for the plant-eater's capacious gut, which was accommodated, as usual, in front of its hips. From the Late Cretaceous rocks of Montana comes possible evidence of how hypsilophodonts lived. Ten dinosaur nests were unearthed there in 1979. Each nest contained about 24 small, ellipsoidal eggs, arranged in a circular pattern, all with the pointed ends downward. The remains of young hypsilophodonts were found in the same area. From this indirect evidence, paleontologists surmise that the young left the nest immediately on hatching, but remained in the same area for a time, being cared for by their parent or parents. The fact that the eggs were so precisely arranged in the nests suggests that there was certainly some parental care, at least before birth. Modern turtles and alligators lay their eggs carefully in well-concealed nests in a similar manner, though both species then vacate the nesting site. In contrast, when the eggs of sauropod dinosaurs have been found, they are always laid out in lines, as though the female dropped them while on the move, rather than collecting them together in a nest. This suggests that the young of sauropods were on their own after they hatched out.
	Classification:FAMILY	Name:hyrachyidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The hyrachyids mark the transition between tapirs (see pp. 258-261) and rhinoceroses, the latter evolved from a tapir similar to Hyrachyus in the Late Eocene, about 40 million years ago.
	Classification:FAMILY	Name:hyracodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The hornless hyracodont rhinoceroses, of which there are about a dozen genera, were the earliest and most primitive family of the group. They probably evolved from a tapiroid close to Hyrachyus. Their large, efficient cheek teeth were similar to those of the tapirs, but their incisors and canines were modified in various ways. Earlier hyracodonts were quite horselike in build, with slender, elongated limbs. Later members of the family developed a more robust build.
	Classification:FAMILY	Name:ichthyosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The typical fish lizards belong to this large family, which flourished throughout the Jurassic period and into the Cretaceous. They are known from some remarkably well-preserved specimens , which show them to be highly Spec, ialized marine animals. The ichthyosaurs had developed a streamlined body, torpedo-shaped, with a stabilizing dorsal fin on the back; short, paired paddles for steering; and a strong, fishlike tail with 2 equal lobes for swimming. Ball-and-socket joint', between the tail vertebrae allowed for powerful strokes from side to side. The tail, together with the great flexibility of the backbone, propelled the animal ' rapidly through the water - the swimming method used by modem, fast-moving fishes.
	Classification:FAMILY	Name:iguanodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Iguanodon is the most popular and familiar member of this family of large, plant-eating ornithopod dinosaurs. The iguanodonts evolved in the MidJurassic, about 170 million years ago, and spread throughout the world. They have even been found within what is now the Arctic Circle, although these lands would have been ice-free all those millennia ago. Iguanodonts reached their peak of diversity and abundance by the end of the Early Cretaceous. Thereafter they declined, and finally died out at the end of that period. Unlike their ancestors - the gazellelike hypsilophodonts (see pp. 138-141) - iguanodonts did not evolve as running animals. Their bodies were bulky and big-boned; the thigh bones were longer than the shin bones (the relative lengths are reversed in sprinting animals); and both the fore- and hindfeet had heavy, hooflike nails. Iguanodonts, therefore, were probably fairly slow-moving animals that spent most of their time on all-fours, browsing on lowgrowing plants, such as horsetails. The beaklike jaws would nip off the leaves, and the rows of high, ridged cheek teeth grind them down to a pulp. These dinosaurs could also rear up on hindlegs, to reach higher vegetation, and to escape from predators.
	Classification:FAMILY	Name:interatheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Most interatherfids were quite small, rodentlike mammals. They were a longlived group, with fossil representatives dating from the Late Paleocene through, to the Late Miocene.
	Classification:FAMILY	Name:isotemnidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The isotemnids evolved early and represent the most primitive family of toxodonts.
	Classification:FAMILY	Name:kuehneosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family are among the earliest-known lizards. Early though they were, they had a specialized lifestyle - that of gliding through the air on outstretched, winglike membranes.
	Classification:FAMILY	Name:lemuridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Lemurs are similar to the adapids, but have a long "comb" derived from the front teeth in the lower jaw, which is used for grooming. About 50 million years ago, lemurs and their close relatives were found throughout Africa, Europe and North America. Today, the lemurs, the Indri lemurs and the aye-ayes survive only in Madagascar.
	Classification:FAMILY	Name:leontiniidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The relationship of this family to other groups is uncertain, but from the structure of the feet it seems reasonable to include it among the toxodonts. Leontinfids were powerfully-built animals, and some may have had a rhinoceroslike horn.
	Classification:FAMILY	Name:leptopterygiidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family contains the last surviving members of the ichthyosaurs before they became extinct at the base of the Late Cretaceous. Like the earlier stenopterygiids (above), the leptopterygiids had narrow paddles, with a great number of bones in each of the 5 toes.
	Classification:FAMILY	Name:macropodidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The most familiar of the modern marsupials, the kangaroos and wallabies, are included in the family Macropodidae.
	Classification:FAMILY	Name:mammutidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Despite their names, these were not mammoths but mastoclonts. Their cheek teeth are characterized by having a simple pattern of low, flattish-sided cusps arranged to form transverse ridges with open valleys between. This contrasts with gomphotherid teeth, which have much more complex cusps in transverse rows, and many smaller cusps filling the valleys between.
	Classification:FAMILY	Name:manidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The sole family in the Order Pholidota, these are the pangolins - curious mammals covered in scales made of densely fused hairs, which give them the appearance of giant animated pine cones. They have stout limbs adapted for digging. Pangolins are often grouped together with the anteaters and armadillos because of their similar lifestyle: they feed largely on ants and termites. However, this is probably an arrangement of convenience rather than a reflection of any close relationship. The extreme specializations of all these creatures make it difficult to determine their true relationships. All 7 living species of pangolins are placed in the single genus Manis. They are found in tropical Africa and Southeast Asia.
	Classification:FAMILY	Name:megalosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The earliest well-known carnosaurs belong to this family of "great lizards." Their remains have been found in North America, Africa and Europe, and as a group they span a period of 140 million years - from the Early Jurassic to the end of the Cretaceous. All were massively built, big-boned creatures. The large head was high and narrow, equipped with powerful jaws and many sharp, saw-edged teeth. The arms were short but strong. The legs were long and massive enough to support the great body weight on the 3 spreading, clawed toes of each foot (a tiny fourth toe was also present), yet light enough to allow the creature to amble along quite quickly.
	Classification:FAMILY	Name:melanorosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family were the largest prosauropods. Some paleontologists think that they may even have been early representatives of the giant, planteating dinosaurs - the sauropods. Melanorosaurs walked exclusively on 4 legs, unlike their smaller, more lightweight contemporaries, the anchisaurs (see p, 124), which could also walk upright, on 2 legs.
	Classification:FAMILY	Name:merycoidodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The suborder Tylopoda may well have evolved from the suborder Suina, as can be seen from this family which seems to combine features of pigs with those of camels. The merycoidodonts (the name means "ruminating tooth") are sometimes more euphoniously referred to as oreodonts - "mountain tooth," a reference to the terrain in which they were discovered. A highly successful group of woodland and grassland browsers, merycoidodonts evolved in North America in the Late Eocene, around 35 million years ago; they were particularly abundant throughout the Oligocene and into the Miocene. They died out around 5 million years ago. Members of the family may have diversified into a variety of habitats. Some fossil merycoidodonts have been found with long tails and clawed digits like those of tree-climbing animals; others have the hippopotamuslike high eyes and nostrils suited to semi-aquatic environments.
	Classification:FAMILY	Name:mesonychidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:When plant-eating mammals (excluding multituberculates) first flourished at the beginning of the Paleocene, they, were no carnivores to prey on them. By the mid-Paleocene, however, above 60 million years ago, some primitive and generalized stock had developed into a new order, the Acreodi. Among them were mesonychids: wolflike, hyenalike or bearlike omnivores able to take advantage of this new source of food. They varied from the size of foxes to the immense Andrewsarchus. The mesonychids flourished until the Early Oligocene, some 35 million years ago, by which time the creodonts and then the true carnivores had become the dominant flesh-eaters. Similarities in the arrangement of bones in the base of the skull and in the teeth suggest that, despite their radically different habitats and lifestyles, the mesonychids may have given rise to the whales and dolphins.
	Classification:FAMILY	Name:mesosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This is the only family of mesosaurs. Its members were all fully aquatic, swimming by means of a long, broad tail and long hindlegs, and steering with the forelimbs. They probably sieved plankton from the water through the fine, pointed teeth in their elongated jaws.
	Classification:FAMILY	Name:metacheiromyidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These earliest and most primitive of the edentates, have uncertain relationships with other edentate groups. They may be the ancestors of the scaly anteaters or pangolins.
	Classification:FAMILY	Name:miacidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The miacids were the earliest true carnivores to appear, during the Paleocene, some 60 million years ago. This is an artificial group, since it contains animals that were not closely related. However, it is a convenient classification that distinguishes these early carnivores from the more modern types. Miacids were mostly small mammals that lived in woodlands, where they were unlikely to become fossilized. The scant remains they have left indicate that they resembled the creodonts in many ways, although they were possibly more intelligent and had better developed meat-shearing teeth.
	Classification:FAMILY	Name:millerettidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The millerettids were a family of anap- sid reptiles with a pair of openings in the skull behind the eyes. This may sound like a contradiction, since the anapsids are that group of reptiles with no openings in their skulls, apart from the eyes and nostrils. In the case of the millerettids, other features of the skull place them firmly in the anapsid group. Most likely, they represent a specialized side branch of the main reptilian tree, and evolved these openings independently. Millerettids were all small insectivores that lived from the Middle to Late Permian in southern Africa. So far, their remains have not been found elsewhere.
	Classification:FAMILY	Name:miolaniidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The land tortoises of this family appeared in the Late Cretaceous period, and only became extinct relatively recently - in the Pleistocene, less than 2 million years ago. Although unable to retract their heads into their shells, they were well protected in other ways.
	Classification:FAMILY	Name:mixosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The mixosaurs had developed a stabilizing fin on the back (like the dorsal fin of a fish) - a swimming aid present in all later ichthyosaurs. But they did not have the typical fishlike tail, with 2 equal lobes, that made their later relatives such powerful swimmers. In mixosaurs, the end of the backbone was not bent sharply down into the tail, as it was in later ichthyosaurs; instead, the vertebrae were extended upward, probably to support a low fin on top of the tail.
	Classification:FAMILY	Name:mosasauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The mosasaurs were a successful, though short-lived, offshoot from the monitor lizard group. They were fully adapted to a marine life, living in in, shore waters during the Late Cretaceous period. Some of them were giants.
	Classification:FAMILY	Name:mustelidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The mustelids probably evolved from the miacids during the Early Tertiary. Modern members of this family include the weasel, stoat, badger, skunk and otter. They are all slim, longbodied hunters, living mainly in temperate latitudes throughout the world. In the tropics, their place is taken by the civets, genets and mongooses.
	Classification:FAMILY	Name:myrmecophagidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The myrmecophagids, or "true anteaters" (to distinguish them from the completely unrelated marsupial anteaters such as the modern numbat Myrmecobius) are highly specialized for exploiting a diet of ants and termites. Their evolution is little known: an early form, Protarnandua, from the Early Miocene about 20 million years ago, was already a typical anteater.
	Classification:FAMILY	Name:necrolestidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family has a single member, the extinct Necrolestes (below), so specialized that it can be classed with no other animal. However, its jaws and teeth do show some resemblance to those of the living golden moles of Africa.
	Classification:FAMILY	Name:nodosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The nodosaurs were the earlier and more primitive of the 2 families of ankylosaur, and ranged throughout the Cretaceous period. Some paleontologists think that they may have evolved in Europe during the Late Jurassic, and then spread to the other northern continents. Some types at least also reached the southern hemisphere - Minmi is a recent discovery from Australia. Nodosaurs had narrow skulls, longer than they were wide. Solid, bony plates covered the body from neck to tail, and long spikes guarded the flanks.
	Classification:FAMILY	Name:nothosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:There are several families of nothosaurs, but the best-known representatives belong to the family Nothosauridae. They have been found in the marine sediments of Europe and Asia, dating from the Early to Late Triassic.
	Classification:FAMILY	Name:notohippidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The term "notohippid" means "southern horse." Yet although it was once thought to be ancestral to the true horses, the similarities-which lie chiefly in the shape of the skull and the cropping incisors-are a result of convergent evolution. In fundamentals, everything is notoungulate.
	Classification:FAMILY	Name:notostylopidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Notostylopid teeth show early specialization. They were somewhat rodentlike, with prominent incisors at the front separated by a diastema from grinding premolars and molars at the back. However, the chisel-shaped incisors, which had roots and did not grow continually as those of a gnawing animal usually do, were adapted for nipping, not gnawing.
	Classification:FAMILY	Name:odobenidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The walruses, or odobenids, differ from the sealions and fur seals in that they are adapted to feed on shellfish rather than on fish. Their upper canine teeth are enlarged into a pair of heavy tusks, in both sexes, and used to prise and probe their mollusk prey from the seabed. By the Early Pliocene, about 5 million years ago, at least 5 genera of walrus, many of them looking rather like sealions, lived on the North Pacific coast. Some of the early walruses swam across the seaway that separated North America from South America in the Late Miocene, about 8 million years ago. By the Early Pliocene, about 3 million years later, they had moved northward to American and European North Atlantic coastal waters. Later in the Pliocene, walruses became extinct in the Pacific, where they had originated. The North Atlantic poptilqtions flourished in the meantime, and groups eventually made their way back to the North Pacific by way of the Arctic Ocean about I million years ago.
	Classification:FAMILY	Name:omomyidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This is the largest family of the tarsiers, a group that still exists today (though in greatly depleted numbers) on some Southeast Asian islands such as Sumatra and Borneo. The omomyids were abundant in the Eocene but declined in the Oligocene and had virtually died out by the beginning of the Miocene. Tarsiers are grouped together as the haplorhim (the "whole noses") because their noses are undivided. Some paleontologists have considered that the tarsiers were the common ancestors of the monkeys and apes, though this seems unlikely given their extreme specialization.
	Classification:FAMILY	Name:oreopithecidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The classification of the oreopithecids is problematical. Some paleontologists regard them as Old World monkeys related to Mesopithecus; others point to their apelike and even hominidlike attributes, such as their probable ability to brachiate (use their arms to swing from branch to branch) and even to walk upright. They are almost certainly an evolutionary blind alley, though, whose advanced features are a result of convergence. There is only 1 genus.
	Classification:FAMILY	Name:ornithomimidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The so-called "bird mimics" were a specialized offshoot of the coelurosaurs. About the same height and proportions as a modern ostrich, they seem to have had a similar lifestyle to that bird, hence the popular name of the group - "ostrich dinosaurs." They were widespread in North America and East Asia in MidCretaceous times, but seem to have died 'out before the end of that period. All were large, long-legged sprinters. They probably traveled the open plains in groups, looking after their young while on the move, as do modern flightless birds. Unlike most other dinosaurs, ornithomimids had no teeth. In place of the teeth, there was a horny, birdlike beak, which was used to snap up small animals and insects. Other special features were exceptionally large eyes and big brains. Both features would have made them well-coordinated, efficient and intelligent hunters.
	Classification:FAMILY	Name:oviraptoridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This small family of toothless theropods lived in Late Cretaceous times in eastern Asia, and were named the "egg thieves" because of their suspected eating habits. They had large heads and short, deep beaks - quite unlike the long, narrow skulls and pointed beaks of their relatives, the ornithomimids or "ostrich dinosaurs" (see p. 109).
	Classification:FAMILY	Name:pachycephalosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The skulls of the so-called "thick, headed lizards," or boncheads, were dome-shaped, giving their owners a bizarre appearance. They had high foreheads and thick skull caps, made up of enormously thickened bones. Some species also had bony frills, knobs and spikes on the back and sides of their heads, and sometimes on their snouts. Most paleontologists believe that these boneheaded dinosaurs bad a similar lifestyle to that of modern mountain goats. Like these mammals, they would have lived together in herds, and the males would most likely have engaged in competitive, head-butting fights to establish a pecking order. In other respects, pachycephalosaurs were like other ornithopods - 2-legged plant-eaters, with 5-fingered hands, 3-toed feet (with a tiny first toe), and a long, heavy tail. As a group they were rare, known mainly from Late Cretaceous times in North America and central Asia. But one bonehead, called Yaverlandia, has been found earlier than this - dating from Early Cretaceous rocks in southern England. Some paleontologists think that the anatomy of the boneheads (especially their skull structure) is sufficiently different from that of the ornithopods to justify placing them in a separate group.
	Classification:FAMILY	Name:palorchestidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family of large herbivores lived in Australia from Miocene to Pleistocene times. They may have been the mar, supial equivalents of the ground sloths.
	Classification:FAMILY	Name:pareiasauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The parciasaurs were the largest of the early, primitive reptiles, reaching lengths of 10 ft/3m. They were massively built herbivores, supported sturdy limbs, which in later members tended to be placed beneath the body that the animals could walk more up- right, rather than sprawl. The pareiasaurs appeared in southern Africa during the Mid-Permian, and had spread to Europe and Asia in large numbers by the end of that they became extinct.
	Classification:FAMILY	Name:pelomedusidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These aquatic turtles were the most prolific of all the pleurodires during Late Cretaceous and Early Tertiary times. There are only 19 living species - in the rivers and lakes of tropical Africa, Madagascar and South America
	Classification:FAMILY	Name:phocidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Seals may not look much like dogs or cats, but they are nonetheless members of the order Carnivora. Grouped as phocids, they probably evolved from an otterlike mustelid, such as Potamo, therium, in the Late Oligocene, some 30 million years ago. They first appeared in European waters, and then spread north and south to the Arctic and Antarctic Oceans, and west to the Pacific, adapting rapidly to a marine, fish-eating lifestyle. However, they must still leave the sea to breed on land. The phocids are often called the "true seals," to distinguish them from the otariids, or "eared seals" (the sealions and fur seals). They are moreabundant and varied today than the sealions, fur seals and walruses, but their fossil record is sparse.
	Classification:FAMILY	Name:pistosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The close relationship of the nothosaurs and plesiosaurs is revealed in the sole member of this family. Most of the skeleton of Pistosaurus is that of a typical nothosaur, but the skull has many plesiosaur features.
	Classification:FAMILY	Name:placodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This group of semi-aquatic reptiles were equally at home walking along the seashore or swimming in the coastal shallows. Both areas provided them with rich feeding grounds for their, preferred diet of shellfish, which were crushed between the broad teeth.
	Classification:FAMILY	Name:plateosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These heavy, large, stout-limbed prosauropods were bigger versions of their contemporaries, the anchisaurs (above). The proportions of their bodies are reminiscent of the giant sauropods that thrived later, in the Jurassic and Cretaceous periods (see pp. 126-133).
	Classification:FAMILY	Name:plesiadapidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These are the best-known of the 5 families of Plesiadapiformes. Examples are plentiful from the Paleocene and Eocene of North America and Europe (roughly 65 million to 40 million years ago), a fact which indicates both a land connection between the continents and a uniformity of conditions between these areas at this time. It is possible that plesiadapids spread from North America to Europe via Greenland, which was at that time a warm, wooded "land bridge." Their features included a long tail, agile limbs with claws rather than nails, a long snout containing rodentlike jaws and teeth, and eyes at the sides of the head.
	Classification:FAMILY	Name:pliohyracidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:All the extinct forms of early Tertiary hyraxes are placed in this family. The later fossil hyraxes and all the living representatives of the order are placed in the Family Procaviidae.
	Classification:FAMILY	Name:podokesauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The earliest and most primitive of the small carnivorous theropods were the podokesaurs. As a family, they survived for some 50 million years - from the Late Triassic to the Early Jurassic. Podokesaurids were little different from their immediate ancestors, the thecodontian reptiles (see pp. 94-97). They were fast, active predators, possibly hunting together in packs. They ran around on long legs, with slender necks and long tails outstretched to balance their bodies. The arms were shorter than the legs, and were used for grasping prey or transferring food to the mouth. The head was wedge-shaped, with many sharp, pointed teeth in the jaws.
	Classification:FAMILY	Name:pongidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The pongids are the fossil and living apes. They are semi-bipedal, sometimes walking on 4 feet and sometimes 2, and have no tail. Today, the pongids are restricted to tropical Africa and South~ east Asia, where 4 genera and 8 species survive. These are the gibbons, 2 species of chimpanzee, and a single species each of gorilla and orangutan. Pongids were once much more diverse both in number of genera and in geographical distribution. The earliest members date from the Early Miocene, around 25 million years ago. In the past, almost every new specimen of hominoid was treated as a separ, ate genus, and given a new name. This became confusing, and certainly held back the understanding of the br d lines of hominoid evolution. It is now increasingly accepted that many of these near-people were in fact closely related, in spite of subtle differences in their anatomies, and should perhaps be thought of as members of the same genus. (There are, after all, quite large anatomical differences among modern humans, too, yet we are I species.) Until recent years, it was generally assumed that apes parted from the evolutionary line that resulted in australopithecines and humans around 15 to 20 million years ago. However, biochemical studies now suggest that this period may be much too long. Detailed investigations have been carried out into our mutual immune responses, and structural differences in DNA (the genetic material incorporated in every living cell) and complex pro, teins such as the hemoglobin in blood corpuscles. Given certain reasonable assumptions about the spontaneous rate of change of these molecules, it would seem that gibbons only split away from the ancestral line about 10 million years ago, with the orangutan parting shortly after. Perhaps the greatest surprise, though, lies in what these studies imply about the relationship between modern humans and chimpanzees and gorillas. Although superficially we seem so different from one another, our biochemistry is too similar for much more than 5 million to 8 million years to have elapsed since we separated. This theory is still controversial, however, not least because fossil australopithecines have been discovered from as long ago as 3.5 million, and perhaps as long as 4 million to 5 million years ago. These seem too much like humans and too little like apes to be the product of only a few million years of evolution.
	Classification:FAMILY	Name:procolophonidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family ranged throughout the world from Late Permian times to the end of the Triassic. Early members were small and lightly built. They were probably quite agile, and crushed insects and other invertebrates with the many, small, peglike teeth in their jaws. Later members, however, from the Mid-Triassic onward, were larger creatures with a very different dentition. Their broad cheek teeth suggest that they ate plants. Strange, bony spikes grew outward from the sides of their skulls, presumably as a means of defense for these heavy, slow-moving herbivores.
	Classification:FAMILY	Name:procyonidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The procyonids, including the modern raccoons, pandas and coatis, first appeared in the Early Oligocene, about 35 million years ago. They had the typical meat-shearing blades on their premolar and molar teeth, the characteristic feature of the true carnivores. But this design has been lost in modern members, and their premolars and molars have reverted to a purely grinding and crushing function. This dentition suits the omnivorous diet of most modern procyonids. However, the diet of the giant panda, Ailuropoda melanoleura, consists almost exclusively of bamboo shoots, and it is probable that this animal is more closely related to the bears than to the raccoons.
	Classification:FAMILY	Name:proganochelyidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Most of the early tortoises belong to this family, and date from the Late Triassic period. The best-preserved skeletons have been found in Germany, although others have come from South, east Asia, North America and southern Africa. Many of the characteristic features seen in modern tortoises were developed at this early stage in their evolution.
	Classification:FAMILY	Name:proterotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The spread of the open plains over the South American continent helped in, duce the evolution of lightly-build running animals. The proterotheres ("first creatures") were horselike animals ranging from late Paleocene to late Pliocene times. Prototheres appear to have undergone many of the same adaptive changes as the early horses in North America, sometimes in advance of developments elsewhere. It is unlikely that they were able to graze, though, since their dentition remains that of browsing animals.
	Classification:FAMILY	Name:protoceratidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Protoceratids - "first horns" -were a family of about 10 genera of early animals that resembled deer but were more closely related to the camels. They inhabited the warmer, sourthern forests of North America for about 35 million years, from the Late Eocene to the Early Pliocene, Their most extraordinary features are their "horns" (in fact, bony outgrowths rather than true horns), which were well-developed in males but reduced or absent in females. Some species simply manifested a variety of bumps and knobs, but others had complex forked structures. Such horns were probably organs of display rather than weapons, though later protoceratids doubtless "sparred" with their rivals. The evolution of skull outgrowths in atriodactyls; whether horns, antlers or ossicones, relate to changes in body size, social behavior patterns and territorial structures. Early ruminants were small, feeding on soft vegetation for which they had to range widely. They used their enlarged canine teeth for defense when necessary. The ruminants moved out of the forests into the new scrublands that were developing, and adapted to feeding on the tougher vegetation there. With this change, the territory required to obtain food diminished in area. As territorial boundaries shrank, so the importance of defending them grew. Difference between the sexes became more pronounced, with larger, heavily armored males bearing antlers or horns defending a harem with many offspring.
	Classification:FAMILY	Name:protoceratopidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The protoceratopids constitute the family of early, primitive horned dinosaurs, although only some of them had horns. They evolved in Asia, in the same region as the parrot dinosaurs (from which stock they probably evolved), but lived there many millions of years later, in the Late Cretaceous period. They also spread to western North America. Like the parrot dinosaurs, the protoceratopids could walk upright, although they probably spent most of their time browsing on all-fours, and only rose up on 2 legs to run away from predators. The protoceratopids were much smaller than their later relatives, the ceratopids. They had teeth in the upper beak, which is considered a primitive feature, lost in the more advanced ceratopids. They had no horns on their heads, or else only rudimentary ones. But they did have the beginnings of the neck frill that was to become so prominent in the later ceratopids.
	Classification:FAMILY	Name:protorothyrididae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Members of this family are the earliestknown reptiles. They first appeared in the Late Carboniferous period, and survived into Mid-Permian times, a span of some 50 million years. The protorothyridids were the basal stock from which many specialized groups evolved, including the ruling reptiles - the dinosaurs, crocodiles and flying pterosaurs (see pp. 90-93).
	Classification:FAMILY	Name:protostegidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The protostegids numbered among their members some of the most spectacular sea turtles that ever lived. All are now extinct, but they thrived during the Late Cretaceous. By that time, the protostegids had developed the 2 main features that distinguish all sea turtles from their land and river-based relatives. First, since there were fewer predators in the sea, they did not need such heavy armor on their backs, and so the shell was reduced to a much lighter structure, which also made them more maneuverable. Sec- ond, the toes of the front and back limbs were greatly elongated, and modified into broad flippers for swimming. Today, only 7 species of sea turtle survive, grouped in 2 families. All are endangered due to man's interference with their habitats, especially the nesting beaches. The green turtle and the great leatherback turtle, both of warm seas, are the most familiar members. No sea turtle, either extinct or modern, can retract its head or legs into the shell.
	Classification:FAMILY	Name:psittacosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The "parrot" dinosaurs were a rare group of ornithischian dinosaurs, found only in the Early Cretaceous rocks of East Asia. Their skulls show trfany features that suggest that they were the ancestors of the horned dinosaurs, or ceratopians. Their bodies, however, were similar to those of the gazellelike* hypsilophodonts, from which stock they probably arose. Like the hypsilophodonts, the parrot dinosaurs could rise up on 2 legs to run away from predators. The suggestion, therefore, is that the early ceratopians, descended from the parrot dinosaurs, were also bipedal, and only reverted to a 4-legged stance later in their evolution.
	Classification:FAMILY	Name:pyrotheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This was the principal family of the order. They ranged from Argentina to Brazil, Venezuela and Colombia, and are found from the Eocene to the early Oligocene.
	Classification:FAMILY	Name:rhinocerotidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This is the family to which modern rhinoceroses belong. They evolved in Late Eocene or Early Oligocene times and thrived throughout North America, Asia, Europe and Africa. However, rhinoceroses began to decline during the Pliocene, and they disappeared altogether from North America at the end of the Miocene, 5 million years ago. Since this was about 2 million years before the Panama Isthmus reformed, rhinoceroses never colonized South America. Neither did the wooly rhinoceros Coelodonta, which was once widespread throughout northern Eurasia, migrate across the Bering land bridge to reach North America. Rhinocerotids adapted to a wide range of diets and habitats. Many were browsers, but some became specialized grazers. Some developed thick coats which enabled them to survive in northern regions even during the Pleistocene Ice Ages. Some also acquired "horns" composed of matted hair, which have not fossilized. It seems likely that the continued decline of these animals, now the largest land mammals after elephants, is as, sociated with changing climate, but also with the rise of humans. Out of about 50 genera, only 5 species are still alive.
	Classification:FAMILY	Name:saurornithoididae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Like the dromaeosaurs, these "birdlizards" were fast, intelligent, rapacious coelurosaurs, though smaller and lighter in build. They also had a sickleshaped, killer claw on each foot. But the skull of these saurornithoidids shows the greatest development. The brain cavity was large; relative to body weight, it was about 7 times the volume of the brain cavity of their modern relative, the crocodile. Combined with this well-developed nervous system, these dinosaurs had large eyes, very likely with binocular vision. Thus, the saurornithoidids of Late Cretaceous times. - living in North America, southern Europe and Mongolia - were among the most efficient hunters of the carnivorous dinosaurs.
	Classification:FAMILY	Name:scelidosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The position of the scelidosaurs in the dinosaur array is controversial. Some paleontologists maintain that they were the ancestors of the stegosaurs, while others believe them to be ancestral ankylosaurs. Here, they are regarded as primitive members of the ankylosaurs.
	Classification:FAMILY	Name:shastasauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The shastasaurs were among the earliest ichthyosaurs to appear, in Mid-Triassic deposits mainly from North America. (Older types are known from Japan and China, dating from the Early Triassic.) At this early stage of their evolution they moved in an eel-like fashion. But by the end of the Triassic period, they had assumed the fish shape characteristic of the ichthyosaur group and swam like modern fishes.
	Classification:FAMILY	Name:spinosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:These dinosaurs were a specialized group of large theropods that may have evolved from the megalosaurs in Cretaceous times. Their special feature was an elongation of the back vertebrae, which produced a pronounced ridge down the center of the backbone. Some spinosaurs had an extreme development of this ridge into a tall crest or "sail," which may have been used to regulate body temperature in the same way as proposed for that of the "fin-backed" pelycosaurs (see pp. 186-189).
	Classification:FAMILY	Name:stegosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:All the familiar stegosaurs belong to this family, including Stegosaurus itself. They evolved in Mid-Jurassic times, some 170 million years ago, and reached their peak of diversity by the end of that period. They spread through western North America, western Europe, East Asia and East Africa. By Early Cretaceous times, the group had started to decline, although some species may well have survived in isolated pockets until the end of the Cretaceous.
	Classification:FAMILY	Name:stenopterygiidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:During the Jurassic period, 2 distinct types of ichthyosaur evolved, differing in the shape of their paddlelike limbs. Ichthyosaurus and members of its family (above) had short, broad paddles, with more toes than the normal 5 sometimes up to 9 toes in each limb. The stenopterygiids, in contrast, had longer, narrow paddles, each made up of 5 toes but with an increased number of bones in each toe.
	Classification:FAMILY	Name:stylinodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Stylinodontids form the only family within the Order Taeniodonta. They varied in size from that of a rat to that of a bear. Taeniodonts evolved quickly in fact, faster than any other mammal group is known to have done - during Paleocene times, and became quite specialized as digging animals.
	Classification:FAMILY	Name:suidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The suids, the pig family, evolved in the Old World, probably in Asia, in Oligocene times, and appeared in Europe in the Miocene. They never colonized the Americas. Although pigs are omnivores rather than herbivores, they seem to have filled the same niches as were taken in the Americas by the peccaries. Fossil suids, like their living descendants, include animals which inhabited tropical rain forests, savannah woodlands, and even semi-aquatic environments.
	Classification:FAMILY	Name:tapiridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The family to which the modern tapirs belong, the Tapiriclae, can be traced back as far as the Early Oligocene, about 40 million years ago. The 4 species of living tapirs are all placed in the single genus Tapirus. Two species occur in Central America and northern South America and 2 in Southeast Asia: none remain in the group's original northern stronghold. This scattered "relict" distribution has often been cited as evidence for the existence of the south, ern supercontinent of Gondwanaland. It is supposed that the animals reached their present homes by migrating overland before the continents slowly drifted apart.
	Classification:FAMILY	Name:tayassuidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The tayassuids or peccaries resemble their close relatives the pigs in so many ways that it is difficult to distinguish them in the fossil record. They are readily identifiable among living suines, however, because a peccary's canines do not protrude when its mouth is closed. Their feet, too, are different, having only 2 toes (with laterals reduced) in the place of a pig's 4 toes (with little reduction in the laterals). Living peccaries are confined to South America and the south-western states of North America, but most of the fossil forms are found in North America, where the family evolved in the Oligocene. Fossil peccaries have also been discovered throughout Eurasia and Africa. They were, and are, versatile creatures, inhabiting a wide range of environments from virtual desert to tropical rain forest.
	Classification:FAMILY	Name:testudinidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Modern land tortoises belong to this family, the most successful of the cryptodires. They appeared in modern form during the Eocene, some 50 million years ago, and have remained practically unchanged since then. All tortoises have high, domed shells to accommodate the capacious gut needed to digest their plant food. The shell also offers complete protection, since the animal can withdraw its head and elephantine legs inside.
	Classification:FAMILY	Name:thylacoleonidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:A family of lionlike marsupials lived in Australia in Pliocene and Pleistocene times. They probably hunted across the Australian grasslands.
	Classification:FAMILY	Name:thylacosmilidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:In this group of large predatory mar, supials, the incisor teeth were lost, and very long upper canine teeth developed, which grew continually. These served as formidable weapons for killing prey.
	Classification:FAMILY	Name:titanosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This was the latest family of sauropods, surviving right to the end of the Cretaceous period. The group was widespread all over the world, especially in the southern continents, and survived for about 80 million years. Not all members of this family were "titans" (the mythical giants of Greek legend), as their name implies. Most averaged 40-50ft/12.2-15.2m long, which was small in comparison to some of the brachiosaurs and diploclocids. To date, only fragmentary remains of titanosaurs have been found, not complete skeletons. They seem to have been like Diplodocits in structure, but with a shorter neck and a high skull that sloped steeply down to the snout. But unlike Diplodocus and other large sauropods, titanosaurs had solid vertebrae; their bones were not hollowed out as a weight-saving adaptation. In addition to this solid skeleton, some animals also had bony armor covering their backs a unique feature among the sauropods.
	Classification:FAMILY	Name:toxodontidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The toxodontids include animals whose teeth were exceptionally high-crowned and curved. They had open roots which grew all the time to compensate for the wear that resulted from feeding on the tough Pampas grasses. The animals themselves looked like rhinoceroses; some even had a horn on the snout.
	Classification:FAMILY	Name:tragulidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family seems to link the suborder Tylopoda with the pecorans - the cudchewing family that contains the deer, the giraffes and the cattle (see pp. 278-281). Accordingly, there is much debate as to the true classification. Always a rare group, it consists of small, hornless, deerlike animals. Only 2 species survive today, Hyemoschus, the African water chevrotain, and Tragulus, the chevrotain of south and east Asia.
	Classification:FAMILY	Name:trigonostylopidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The trigonostylopids may comprise a family of the astrapotherioids, or they may represent an order of their own, Their principal resemblance to the astrapotheres lies in their prominent canine tusks, but the remainder of the teeth suggest that they are more closely related to the litopterns.
	Classification:FAMILY	Name:trionychidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family of soft-shelled turtles first appeared, along with the sea turtles, in the Late Jurassic period. They were an early group of specialized cryptodires, and a relatively successful one, since over 30 species survive today, in the freshwaters of North America, Africa and Asia. The shells of trionychids are low and rounded, and have lost the horny covering that usually protects the underlying bony plates. Instead, a layer of soft, leathery skin covers the shell, hence the name of the family.
	Classification:FAMILY	Name:tyrannosauridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The largest terrestrial carnivores that ever lived belonged to this family of "tyrant lizards." It was a small, specialized group, with less than a dozen types (genera) identified to date. Yet its members have inspired the popular notion of what flesh-eating dinosaurs looked like and how they behaved. The remains of tyrannosaurs have been found in Asia and western North America. As a group they were shortlived, appearing in Late Cretaceous times and disappearing at the end of that period in the mysterious massextinction of all the dinosaurs. Their existence, spanning less than 15 million years, was only a "moment" in terms of the evolution of life.
	Classification:FAMILY	Name:uintatheriidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:Except for Mongolian genus, which had no skull protuberances or saberlike canines, all members of the order Dino, cerata are included in this family. The uintatheres were the largest land mammals of their time, with massive bones, heavy limbs and broad, spreading feet. But their brains were very small - no larger in relation to body size than the brains of many of the dinosaurs. Uintatheres died out in the Oligocene, about 35 million years ago, and were replaced in their ecological niche as massive herbivores by the brontotheres (see pp. 258-261). NAME: Eobasilus TIME: Late Eocene LOCALITY: North America (Wyoming) SIZE: 10 ft/3 m long; 5 ft/1.5 m high at the shoulder The grotesque Eobasitus looked rather like a rhinoceros with a pair of saberlike canine tusks in its upper jaw and 6 bony Zotuberances on its head. These horns were blunt and probably covered with skin. It is also likely that only the foremost pair on top of the nose were sheathed in "horn" formed of matted hair, as in rhinoceroses. They may have been used by the males in head-butting contests to determine herd-leadership. The incisor teeth were very small in the lower jaw and missing entirely from the upper, which suggest that the tongue and tusks were the most important food-gathering organs.
	Classification:FAMILY	Name:ursidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The bears surface later in the fossil record than many other carnivores. They first appeared in Europe during the Oligocene, and since then have spread throughout most of the world. However, there are no bears native to Africa today, although there are 2 separate records of bears in that continent in the past. The primitive Agriotherium lived in southwestern Africa during the Pliocene, some 5 million years ago, and brown bears are known to have lived in the Atlas Mountains of northern Africa during the Pleistocene, even surviving into Recent times. Bears are omnivorous, eating anything from small mammals, fish and insects to eggs, nuts and, of course, honey. Their tooth pattern reflects this Catholic diet, with unspecialized in, cisors, long canines, reduced or absent premolars (with no meat-shearing blades) and broad, flat molars with rounded cusps. The molars probably get used the most, to crush up the tough plant food that makes up the major part of a bear's diet. The modem Kodiak bear (Ursus arctos middendorffi) is the world's largest living land carnivore.
	Classification:FAMILY	Name:varanidae	Age:
	Locality:	Size:	Fossil Name:
	Notes:The monitors were, and still are, the largest of all land lizards. They appeared in the Late Cretaceous period, more than 80 million years ago, and have changed little since. They were large, heavy animals, agile for their size, and active hunters, seeking out their prey with the long, forked tongue that acts as an organ of smell. Modern representatives include the giant Komodo dragon.
	Classification:FAMILY	Name:viverridae	Age:
	Locality:	Size:	Fossil Name:
	Notes:This family of small carnivores contains the modern civets, genets and mongooses. The viverrids are among the oldest of the carnivores, with an ancestry dating back as far as the Middle I Palcocene, about 60 million years ago. They are also among the most adaptable and least specialized of all carnivores. Viverrids are mostly long-bodied, short-legged animals. Many of them are opportunistic omnivores, eating a great variety of food - from earthworms, mollusks, crabs, fish, birds and reptiles (including snakes in the case of mongooses), to eggs, carrion and fruit. Despite the wide range of the group today - they are found throughout much of the Old World tropics (viverrids are the only group of carnivores to have colonized Madagascar) - the fossil record of the viverrids is poor.
	Classification:GENUS	Name:Acanthodes	Age:Early Carboniferous to Early Permian
	Locality:Australia (Victoria), Europe (Czechoslovakia, England, Germany, Scotland and Spain) and North America (Illinois, Kansas, Pennsylvania and West Virginia)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Acanthodes was a member of the last group of spiny sharks to evolve. They had no teeth in their jaws, but the gills were equipped with long bony "rakers" made of toothlike spikes. Acanthodes and its relatives were probably filterfeeders, sieving tiny, planktonic animals through their gills. Like all later acanthodians, Acanthodes was larger than its earlier relatives; some members of its group reached lengths of over 6 ft 6 in/2m. Acanthodes was also less spiny than earlier forms. Its paired pectoral fins still had stout spines, as did the large anal fin. But there was only one spiny dorsal fin, set far back near the tail, and the pair of the ribbonlike pelvic fins that ran along the belly each had a single spine. Thus, Acanthodes only had 6 fin spines on its body, compared with the 15 spines of its prickly relative, Climatius.
	Classification:GENUS	Name:Acrocanthosaurus	Age:Early Cretaceous
	Locality:North America (Oklahoma)	Size:43 ft/13 m long	Fossil Name:
	Notes:In 1950, several skeletons of this enormous, flesh-eating dinosaur were found in North America. Its name means "top spiny lizard," and refers to the elongated spines (up to 1 ft/30 cm long) that grew up from its backbone. These would have been covered by a web of skin, to form a pronounced ridge or crest running down the length of the back. The crest of Acrocanthosaurus was low in comparison to that of some of its relatives living in other parts of the world. For example, Altispinax' of western Europe had spines that were 4 times the length of the vertebrae from which they grew, while Spinosaurus of Africa had a "sail" over 6 ft/ 1.8 m high on its back (below).
	Classification:GENUS	Name:Acrophoca	Age:Early Pliocene
	Locality:South America (Peru)	Size:5 ft/1.5 m long	Fossil Name:
	Notes:Acrophoca may have been the ancestor of the modern leopard seal, Hydrurga leptonyx. Like that species, it was a fisheater, but it seems to have been less adapted to an aquatic life, and spent much of its time on or near the shore. Its flippers were not so well developed, its neck was longer and less streamlined than that of a modern seal (more like that of its otterlike ancestor), and its snout was quite pointed.
	Classification:GENUS	Name:Adinotherium	Age:Early to Middle Miocene
	Locality:South America (Argentina)	Size: 5 ft/1.5 m long	Fossil Name:
	Notes:Adinotherium looked rather like a sheep-sized, and less ungainly, version of Toxodon. The front legs were relatively longer than in some toxodontids, so the shoulders were about the same height as the hips, and there was no hump. Adinotheriurn also had a small horn on the skull. This was probably some kind of display structure. Ungulates - hoofed mammals represent the main group of large planteating land animals living today. Their earliest representatives were early rooters and browsers, which had been dominant during the Paleocene and Eocene periods, about 50-60 million years ago. Many evolved to take advantage of the new opportunities presented by the formation of open grassy plains during the drier Miocene period, about 20 million years ago.
	Classification:GENUS	Name:Aepycamelus	Age:Middle and Late Miocene
	Locality:North America (Colorado)	Size:10 ft/3 m high at the head	Fossil Name:
	Notes:The giraffelike camel line reached its climax in Aepycamelus, formerly known as Alticarnelus because of its extraordinary height. The legs were long and stiltlike, and the 2 toes had very small hooves. Aepycamelus, then, had lost the running hooves of its ancestors and put in their place the broad pads of modern camels. The modern camel moves both legs on one side of the body in the same direction at the same time, This method of walking is known as pacing, and is confined to camels and giraffes. Pacing is a very efficient method of traveling great distances across open terrain. An extremely long-legged animal such as Aepycamelus must have moved with a similar gait. Indeed there is some direct evidence for this in camel-like footprints that have been discovered in Miocene deposits.
	Classification:GENUS	Name:Aepyornis titan	Age:Pleistocene to Recent
	Locality:Madagascar	Size:up to 10 ft/3 m tall	Fossil Name:
	Notes:The extinct, flightless birds of the genus Aepyornis, of which this species is the Iargest, were heavily built creatures, probably weighing up to 12 US ton/ 500 kg. Their common name - elephant birds - stems from old Arabian tales of a giant creature the "rukhkh," that could pounce on an elephant and carry it up into the air. Aepyornis may be the legendary "roc" bird encountered by Sinbad in The Book of a Thousand and One Nights. Each of Aepyornis' elephantine legs ended in 3 stumpy toes, which were spread wide to carry the body weight. The thick thigh bones were greatly elongated, evidence that this bird was not a runner, unlike its relative, the ostrich - the fastest creature on 2 legs. Aepyornis laid huge eggs - more than 1 ft/30 cm long, with a capacity of some 19 US pints/9 liters, and when fresh they may have weighed 20 lb/ 10 kg. Apart from size and strength, the elephant bird had no special defenses no teeth in its beak, no talons on its feet, no wings for flying. But the only large predators in its island home were crocodiles, easily avoided. When man arrived in Madagascar, less than 1500 years ago, species of Aepyornis were still alive. This bird may have become extinct only in the 17th century.
	Classification:GENUS	Name:Agriotherium	Age:Late Miocene to Pleistocene
	Locality:Africa (Namibia), Asia (China) and Europe (France)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:Although bears are not found in Africa today, they lived there in the past. Agriotherium lived in southwestern Africa, a whole continent away from its usual haunts of Europe and Asia. Agriotherium was a very large bear, even larger than the Kodiak bear. It was also very primitive, and looked rather like a dog in some ways. However, its teeth had developed the typical bear pattern. It is therefore safe to assume that was omnivorous.
	Classification:GENUS	Name:Alamosaurus	Age:Late Cretaceous
	Locality:North America (Montana, New Mexico, Texas and Utah)	Size:69 ft/21 m long	Fossil Name:
	Notes:This was among the last sauropods to live before the mass-extinction of the dinosaurs at the end of the Cretaceous period, 65 million years ago. During Late Cretaceous times, there had been a climatic change in many parts of the world. Much of lowland North America had turned into moist, swampy jungle, which was the domain of the ornithopod dinosaurs - 2-legged sprinters with birdlike feet (see pp. 135-153). But there were still some high, dry places where the sauropods could live. It is appropriate that this section on the great saurischian dinosaurs should end with Alamosaurus. It was one of the last dinosaurs to survive, and, perhaps coincidentally, is named after the Alamo, that famous fortress in San Antonio where the Texans made their last stand in 1836 against the Mexicans.
	Classification:GENUS	Name:Albertosaurus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:26 ft/8 m long	Fossil Name:
	Notes:This "small" tyrannosaur shows all the features common to the family. It was massively built, with a big head and short body, balanced at the hips by a long, strong tail. Pillarlike legs, with 3, toed, spreading feet, supported the body weight. Albertosaurus and other members of its family were specialized theropods. Their arms were puny in comparison to the body size. They were so short that they could not have reached up to the mouth. There were only 2 fingers on each hand, which would not have been very effective for grasping prey. And although the jaws could be opened wide, the bones of the skull were rigidly fixed, without the same degree of flexibility as between those in the skulls of the allosaurs (see p. 117). Tyrannosaurs had a well-developed second set of ribs on the underside of the body. A possible explanation for these extra ribs and the short arms could be that when a tyrannosaur rested, it lay on its belly. The innards would have been supported by the extra ribs, and not crushed by the great weight of the body. When the animal got up, its tiny arms stopped the bulky frame from sliding forward, and steadied it as it: rose to its feet. There is also a suggestion that the tiny arms were used by the males to hold onto the females while mating.
	Classification:GENUS	Name:Alioramus	Age:Late Cretaceous
	Locality:Asia (Mongolia)	Size:20 ft/6 m long	Fossil Name:
	Notes:A group of Asiatic tyrannosaurs, represented by Alioramus, differed from "typical" tyrannosaurs in the shape of their skulls. Whereas most members of the family had deep skulls with short snouts, Alioramus and its relatives had shallow skulls with long snouts. There were also some bony knobs or spikes on the face between the eyes and tip of the snout. These may have been display features to distinguish the sexes, perhaps with the males having larger structures than the females. Alioramus and its tyrannosaur relatives lived in Asia and western North America during the Late Cretaceous period. At that time, the modern continents of Asia and North America were joined into one landmass; the Bering Strait that separates them today was then dry land (see pp, 10-11). But the North American part was divided in two by a shallow sea that ran north-south, and halved the land into "Asiamerica" to the west, and "Euramerica" to the east. Animals, including the great tyrannosaurs, could have migrated freely between Asia and western North America, but relatively few seem to have managed to cross the great divide over to the eastern half of the landmass. However, the remains of one tyrannosaur, similar to Albertosaurus (above), have been found in the eastern USA.
	Classification:GENUS	Name:Allosaurus	Age:Late Jurassic to Early Cretaceous
	Locality:North America (Colorado, Utah and Wyoming), Africa (Tanzania) and Australia	Size:up to 39 ft/12 m long	Fossil Name:
	Notes:This enormous carnosaur, the largest of the allosaurs, was the most fearsome predator of the Late Jurassic. It must have weighed between I and 2 US tons/1-2 tonnes, and stood some 15 ft/4.6 m tall. In appearance, it was a bigger version of its close relative and contemporary Megalosaurus (above), although it had a few peculiarities of its own. The head, for example, had 2 bony bumps above the eyes, and a narrow bony ridge running from between the eyes down to the tip of the snout. The skull was massive in size, but not in weight. This was due to several large openings ("windows" or fenestrae) between various bones of the skull that reduced its solid structure to an intricate network of bony struts, so lightening its weight. The bones themselves were only loosely articulated with one another (a feature also seen in the skulls of other large carnosaurs, such as Ceratosaurus, below). This resulted in a degree of flexibility, which added to the strength of the lightly built skull. Allosaurus' efficiency as a hunter is a matter of debate. Some paleontologists think it was too heavy and clumsy to run down prey, and therefore probably fed on carrion. Others believe that it was quite agile for its size, and may even have hunted in packs to bring down the giant, plant-eating dinosaurs of the day, such as Apatosaurus (= Brontosaurus) and Diplodocus. Bones of Apatosaurus have, in fact, been found in western North America with the marks of teeth similar to those of Allosaurus on them, and similar, broken teeth have also been found scattered around other specimens of this plant-eater.
	Classification:GENUS	Name:Alphadon	Age:Late Cretaceous
	Locality:North America (Alberta to New Mexico)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Primitive marsupials such as Alphadon were probably very similar to modern opossums. They were omnivores, and ate a wide range of foods, including insects, small vertebrates and fruit. They were probably also tree-dwellers, able to climb well, using feet equipped with opposable toes, which could be brought together to give a good grip, and prehensile tails. Their small size and tree-dwelling habits would have meant that they did not compete directly for food with the Late Cretaceous dinosaurs, and so were able to survive alongside them.
	Classification:GENUS	Name:Amphicyon	Age:Middle Oligocene to Early
	Locality:Europe (France and Germany) and North America (Nebraska)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:Amphicyon was a typical "bear-dog." It probably looked like a large bear with the strong, sharp teeth of a wolf. It had a thick neck, strong legs and a heavy tail. It may have led a similar life to that of a modern brown, or grizzly, bear, eating a wide range of plant and animal foods, and killing its prey with powerful blows from its strong forefeet. Amphicyon must have been a fearsome adversary for any other creature living on the plains of the northern hemisphere in Mid-Tertiary times, about 30 million years ago. One fossil species, Amphicyon giganteus, from the Miocene of Europe, was the size of a modern tiger.
	Classification:GENUS	Name:Anagale	Age: Early Oligocene
	Locality:Asia (Mongolia)	Size: 1 ft/30 cm long	Fossil Name:
	Notes:Anagale may have looked like a modern rabbit, but it had a long tail and, probably, short ears. It also ran about, rather than Jumping rabbit-style. This is conjectured from the proportions of the bones in its hindlegs. Anagale's hindlegs were a little longer than the forelegs, and they were equipped with spadelike claws on the feet. Anagale probably searched through the soil for beetles, grubs, worms and the like. The fact that the teeth in many specimens found are thoroughly worn down suggests that it also ate the soil - perhaps the easiest way of extracting food from it.
	Classification:GENUS	Name:Anancus	Age:Late Miocene to Early Pleistocene
	Locality:Widespread in Europe and Asia	Size:10 ft/3 m high	Fossil Name:
	Notes:With its short lower jaw and long, prehensile trunk, Anancus looked much like a modern elephant; but it had shorter legs, and an extremely long pair of tusks. These tusks in the upper jaw were straight and, at 10-13 ft/3-4 min length, were nearly as long as the rest of the animal. Anancus seems to have been perfectly adapted to woodland life, being able both fo browse from high branches and to root about among the leaf litter of the forest floor. Anancus became extinct when grasslands replaced the woodlands in which it lived.
	Classification:GENUS	Name:Anatosaurus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:33ft/10m long	Fossil Name:
	Notes:The popular name for this group of dinosaurs, the "duckbills," was coined after the discovery of the broad, flat skull of this hadrosaur in western North America. The name Anatosaurus, in fact, means "duck lizard," and refers to its horny, toothless bill or beak. Several well-preserved skeletons of Anatosaurus have been found. From these, paleontologists can tell that this duckbill was over 30 ft/9 In long, stood some 13 ft/4 In tall, and probably weighed about 4 US tons/3.6 tonnes. Two "mummified" specimens were also found - a rare discovery - with driedup tendons and the contents of their stomachs intact. The last meal eaten by these 2 individuals consisted of pine needles, twigs, seeds and fruits. Impressions of the animals' skin were also preserved, stamped into the surrounding rocks. Though all the skin had long since rotted, these impressions show that Anatosaurus was covered in a thick, leathery hide. The same mummified specimens appeared to have had webs of skin between the 3 main fingers of each hand. At first, this seemed to reinforce the theory that duckbills were aquatic animals, using their webbed hands and flattened tails for swimming. But closer examination indicated that the hands could not be stretched widely, and the webs of skin were more likely to be the shriveled-up remains of weight-bearing walking pads, calloused with wear like those on the feet of modern camels. Such pads tie in with the presence of hooflike nails on 2 of the main fingers of each hand, and support the current theory that duckbills were true landdwellers that walked mainly on all-fours.
	Classification:GENUS	Name:Anchiceratops	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:20 ft/6 m long	Fossil Name:
	Notes:The long-frilled Anchiceratops lived near the very end of the Late Cretaceous period, later than its relative Chasmosaurus. In fact, it may even have descended from that dinosaur. Although it was larger than Chasmosaurus, Anchiceratops was somehow more streamlined. Its body was longer, with a shorter tail, and the tall neck frill was considerably narrower. Two long, narrow horns curved forward from the brow, and a shorter nose horn pointed directly ahead. The frill was divided along its midline by a strong ridge, on either side of which were medium-sized openings in the bone. A pair of hornlike protuberances pointed forward at the top-rear edge of the frill. The remains of Anchiceratops were found in delta deposits mixed with beds of coal, and dating from the topmost rocks of the Late Cretaceous. This suggests that it may have lived in or near swamps, feeding with its sharp beak and shearing cheek teeth on the abundant vegetation that grew in this waterlogged environment - plants such as swamp cypresses, ferns, giant redwoods and cycads.
	Classification:GENUS	Name:Anchisaurus	Age:Early Jurassic
	Locality:North America (Connecticut) and southern Africa	Size:7 ft/2.1 m long	Fossil Name:
	Notes:This early dinosaur was probably typical of the small prosauropods. It had a small head, tall, flexible neck and long, slim body. The arms were shorter than the legs, by about a third. Each hand had 5 fingers, though the 2 outer ones were quite short. The first finger, or "thumb" had a large claw, which may have Seen used for rooting up plants or maybe for fighting.
	Classification:GENUS	Name:Anchitherium	Age:Early to Late Miocene
	Locality:North America and later Asia and Europe	Size:2 ft/60 cm high at the shoulder	Fossil Name:
	Notes:The evolution of the horse was not a simple "straight line" affair, and a number of side-branches developed which have left no descendants today. Anchithenum represents a very successful but conservative offshoot.
	Classification:GENUS	Name:Andrewsarchus	Age: Late Eocene
	Locality:Asia (Mongolia)	Size:13 ft/4 m long	Fossil Name:
	Notes:With a gigantic skull nearly 3 ft/ I In in length, Andrewsarchus was the largest known terrestrial carnivorous mammal. The teeth were very large and adapted for crushing and tearing food. Andrewsarchus' lifestyle is still something of a mystery since complete skeletons have never been found. Compari, son with its relatives suggests it was not a hunter that actively pursued its prey but a carrion, eater, like most hyenas are today.
	Classification:GENUS	Name:Ankylosaurus	Age:Late Cretaceous
	Locality:North America (Alberta and Montana)	Size:up to 33 ft/10 m long	Fossil Name:
	Notes:This is the largest-known ankylosaur, and one of the last of the group to survive, right to the end of the Cretaceous period. It was massively built, and probably weighed a good 4 US tons/3.6 tonnes. Its skull was about 2 ft 5 in/ 76 cm long. Its body was broad (16 ft/5 in at the widest point) and squat, supported on strong, stumpy legs set directly beneath the body. Thick bands of heavy armor ran across the animal's back, from the top of the head to near the tip of the tail, which ended in a great, bony club. The armor consisted of hundreds of ovalshaped plates set close together, and embedded in the leathery hide. This open arrangement would have given great flexibility to the armor plating. Ankylosaurus had a blunt snout, broad face and toothless beak. Two spikes stuck out on either side at the back of the head, and 2 more projected from each cheek. When attacked, Ankylosaurus would probably have stood its ground, well protected by its body armor. When the predator got within range, the heavy, clubbed tail was swung sideways, and if it hit its target, the attacker would have been severely wounded.
	Classification:GENUS	Name:Anoplotherium	Age: Late Eocene to Middle Oligocene
	Locality:Europe (France)	Size:3 ft 3 in/1 m high at the shoulder	Fossil Name:
	Notes:Anoplotherium was another of the tapirshaped browsers so common in the forests of the Early Eocene. As in the other early forest-dwelling ungulates, the running habit had not developed very far. Anoplotherium was heavily built, with a long tail, and toenails which looked more like claws than hooves.
	Classification:GENUS	Name:Anurognathus	Age:Late Jurassic
	Locality:Europe (Germany)	Size:1 ft/30 cm wingspan	Fossil Name:
	Notes:This comparatively small rhamphorhynch had a deep, narrow head with short jaws, which were filled with strong, peglike teeth. This could suggest that it lived on a diet of insects. Unlike other rhamphorhynchs, it had a short tail, and this feature, combined with the small body size, would have made it highly maneuverable in flight after its fast-moving prey.
	Classification:GENUS	Name:Apatosaurus	Age:Late Jurassic
	Locality:North America (Colorado, Oklahoma, Utah and Wyoming)	Size:up to 70 ft/21.3 m long	Fossil Name:
	Notes:The giant, plant-eating dinosaur Apatosaurus was once known by the more familiar, and evocative, name of Brontosaurus. This means "thunder lizard," and could be a reference to the noise its 33 US tons/30 tormes must have made as it walked through its homeland in today's western USA. But Brontosaurus was the second name allocated to remains of the beast. So, according to strict scientific convention, it is more properly called by the first name given to it - Apatosaurus. Up until 1975, the skull of Apatosaurus was unknown, although the rest of its skeleton had been discovered about 100 years before. The head of this giant sauropod was tiny in comparison with its body - a mere 22 in/55 cm long out of a total body length of over 65 ft/20 in. Although not as long as Diplodocus, Apatosaurus was simply a bulkier version of it. Both animals had long, slender teeth that grew only at the front of their jaws. As they became worn, they were replaced by new ones. Both animals could rear up on their hindlegs to crop the highest vegetation - though this would have been much more of an effort for Apatosaurus since it weighed 3 times as much as Diplodocus. However, Apatosaurus' great weight could have been used effectively against a predator like Allosaurus - the planteater could have reared up and then brought its forelegs down to crush its enemy. Sometimes this ploy did not work; many bones of Apatosaurus have been found scored with tooth marks similar to those of Allosaurus (see p. 117). An alternative explanation is, of course, that the carnivore came across dead Apatosaurus, and fed off their corpses. Apatosaurus had a longer tail than Diplodocus, made up of no less than 82 interlocking vertebrae (as compared with 73 in Diplodocus). Like Diplodocus, it had pairs of bony skids on the under, side of the tail vertebrae, which protected the soft tissues of the tail. Apatosaurus could have used its heavy tail as a great whiplash to deter at, tackers. The tail was powered by strong back muscles, which were anchored to tall spines projecting from the vertebrae of the lower body. Like Diplodocus, Apatosaurus had 5 short toes on each foot, with one claw on the "big toe" of each front foot, and 3 claws on each back foot. There were thick wedges of weight-bearing cartilage in the ankle joints (as in those of modern elephants), for flexibility and to spread the body weight.
	Classification:GENUS	Name:Araeoscelis	Age:Early Permian
	Locality:North America (Texas)	Size:2 ft/60 cm long	Fossil Name:
	Notes:Araeoscelis was the closest relative of Petrolacosaurus (above), although it lived several million years later. Both animals were similar in appearance - lizardlike creatures, with long running legs, long necks and small heads. The teeth of Araeoscelis, however, were different to those of its earlier relative, and indicate that it may have been a more specialized feeder. Instead of sharp, pointed teeth, Araeoscelis had fairly massive, blunt, conical teeth. These would have been ideal for crushing the tough chitinous covering of insects such as beetles. Associated with this specialized diet was a structural change in the skull of Araeoscelis. One of the 2 pairs of openings in its otherwise-typical diapsid skull had been closed over with bone. This was probably an adaptation to strengthen the skull, so that the animal could develop a more powerful bite to deal with its tougher food.
	Classification:GENUS	Name:Arandaspis	Age:Early Devonian
	Locality:Europe (UK and Belgium)	Size: 8 in/20 cm long	Fossil Name:
	Notes:Pteraspis is typical of the pteraspid family of heterostracans, which became very numerous and diverse during the Late Silurian and Early Devonian. Although it lacked paired fins, Pteraspis was a powerful swimmer, to judge by several hydrodynamic features of its body. Stability was provided by bony outgrowths from the back of the head shield - a large spine acted as a kind of dorsal fin, while 2 rigid "wings" or keels functioned as pectoral hydrofoils. The long, flexible tail was also hydrodynamic, with the lower lobe elongated to provide lift at the front of the body during swimming. Additional lift was provided by the elongated snout, which was drawn out into a bladelike "ros, trum," below which the mouth opened. Paleontologists think that Pteraspis and its relatives fed in mid-water or near the surface of the sea, among the shoals of planktonic, shrimplike crustaceans.
	Classification:GENUS	Name:Archaeopteryx lithographica	Age:Late Jurassic
	Locality:Europe (Germany)	Size:14 in/35 cm long	Fossil Name:
	Notes:The discovery of Archaeopteryx is a classic in the history of paleontology. In 1861, blocks of fine-grained limestone were being cut in a quarry at SoInhofen, southern Germany. These rocks are of Late Jurassic age, some 150 million years old; one split slab revealed the almostperfect skeleton of Archaeopteryx, the first-known bird. Not only were most of its delicate bones intact, but the impression of its feathers was stamped in the rocks, preserved in their natural positions on the wings and tail. A glassfiber cast of this specimen is displayed in London's Natural History Museum. A second, more complete specimen was discovered from the same site in 1877, and this slab of rock, together with its priceless occupant, is now housed in East Berlin's Humboldt University Museum. Four. more specimens are now known. These fossil finds reveal a creature about the size of a modern pigeon, with a small head and large eyes, pointed teeth in its jaws and a long bony tail. Its limbs were, long and slender, with 3 clawed digits on each elongated hand, and with typical bird feet. The lower-leg bones were long, and indicate a running animal (see p. 173). This description does not wholly fit in with the picture of most modern birds, but Archaeopteryx had 2 unmistakeable features, unique to birds. It had a well-developed wishbone (formed by the union of the 2 collar bones) and the typical feathers of a bird, attached to its long arms and tail. Were it not for these birdlike characters, Archaeopteryx could easily be mistaken for one of the coelurosaurs small, 2-legged, carnivorous dinosaurs (see pp. 106-109). Indeed, one of the most recent Archaeopteryx specimens, discovered in Germany in 1951, was attributed to the coelurosaur Compsognathus until the early 1970s, when impressions of its feathers were noticed. Most paleontologists believe that Archaeopteryx was an insectivorous creature that lived in open forests, and could fly or glide from tree to tree. It may have caught insects on the wing as it flew, or perhaps it swooped down in surprise attacks on ground-living invertebrates. Its clawed hands and feet could have been used to climb trees, in order to launch itself on the next flight. The sternum, or breast bone, of Archaeopteryx appears to have been tiny, unlike the great, keeled sternum of modern birds, which provides the main site for the attachment of powerful wing muscles. Some paleontologists have suggested that the feathers of Archaeopteryx were merely for insulation, rather than for flight. This ancestral bird was almost certainly warm-blooded, like its modern relatives. By controlling its body temperature, it could have led a more active, predatory life. However, Archaeopteryx's feathers are so similar in structure and arrangement on the wings to those of modern birds that it is almost certain they were used for flying, even if this was less powerful than the flight of modern birds.
	Classification:GENUS	Name:Archaeothyris	Age:Late Carboniferous
	Locality:North America (Nova Scotia)	Size:20 in/50 cm long	Fossil Name:
	Notes:This small, lizardlike creature is the earliest-known pelycosaur, a member of the ophiacodont family. Its remains were found in the same Late Carboniferous (Pennsylvanian) locality as those of the first-known reptile, the anapsid Hylonornus. These rocks indicate a warm, tropical, humid climate, with great forests of conifers and a rich undergrowth of ferns and club mosses. In the lowland swamps, masses of decaying vegetation accumulated (the coal beds of today), providing food and breeding grounds for insects and other invertebrates. They, in turn, attracted insectivorous reptiles, such as Hylonomus, which were probably preyed upon by the larger, newly evolved synapsid reptiles, such as Archaeothyris. Archaeothyris was already more advanced than the other early anapsid reptiles. Its jaws were strong, and could be opened wide and snapped shut. Although its teeth were all the same shape - sharp and pointed - they were of different sizes, including a large pair of canines at the front of the jaws. Such teeth suggest a varied, carnivorous diet.
	Classification:GENUS	Name:Archavotherium	Age:Early Oligocene to Early Miocene
	Locality: North America (Colorado) and Asia (China, Mongolia)	Size: 4 ft/1.2 m long	Fossil Name:
	Notes:Archaeotherium would have looked like a warthog with a narrow, crocodilelike head. Its skull was remarkably elongated, with long knobs of bone beneath the eyes and on the lower jaw. These protrusions may have been ornamental, or they may have anchored particularly powerful jaw muscles, used for grinding up tubers and tough roots, The arrangement of teeth suggests that, like a pig, Archaeotherium could eat just about anything, even scavenging on the corpses of animals. The shoulders were high, owing to a series of long spines on the vertebrae which anchored the strong neck muscles needed to support the heavy head. The brain itself was tiny, but it had large (olfactory) lobes associated with the sense of smell. Archaeotherium probably spent much of its time with its head down, snuffling and grubbing about in the soil of the Oligocene scrub for food.
	Classification:GENUS	Name:Archelon	Age:Late Cretaceous
	Locality:North America (Kansas and South Dakota)	Size:12 ft/3.7 m long	Fossil Name:
	Notes:This giant turtle of the Cretaceous seas did not have the heavy, many-plated shell characteristic of its land and freshwater relatives. Instead, the shell of Archelon was reduced to a framework of transverse struts, made from the bony ribs that grew out from its backbone. Most probably, the ribs were covered by a thick coat of rubbery skin (as seen in the modern leatherback turtle), rather than by the usual plates of horn. The limbs of this ancient sea turtle were transformed into massive paddles that would have cleaved the water in powerful, vertical strokes - the method is comparable to the underwater flight of penguins, which propel themselves along by flapping their wings. The front flippers of Archelon were well developed, and would have provided the main propulsive force. Like the modern leatherback turtle, Archelon probably fed on a diet of jellyfish, whose soft bodies were easily dealt with by the reptile's weak jaws and toothless beak.
	Classification:GENUS	Name:Ardeosaurus	Age:Late Jurassic
	Locality:Europe (Germany)	Size:8 in/20 cm long	Fossil Name:
	Notes:This early gecko had the flattened head and large eyes typical of its modern relatives. Like them, it was probably a night-hunter, agile enough to snap up insects, spiders and smaller lizards with its powerful jaws. Whether it had the "friction pads" of today's geckos is not known; these are specialized scales under the toes which enable the animal to climb up smooth, vertical surfaces.
	Classification:GENUS	Name:Argentavis magnificens	Age:Late Miocene
	Locality:South America (Argentina)	Size:5 ft/1.5 m tall	Fossil Name:
	Notes:Argentavis magnificens was a vulture with an enormous pair of wings compared with its body size. Although only some of its bones have been found, estimates place this bird's wingspan at about 24 ft/7.3 In - twice the wingspan of the longest-winged living bird, the wandering albatross. A bird of this size did not fly by flapping its wings. Like modern vultures, it would have conserved its energy by gliding from one food source to another, using as few wingbeats as possible. Launching itself from high places, it used the rising thermal currents of warm air during the day to keep it aloft. As with the modern albatross, its initial take-off technique was probably awkward, especially when running over uneven ground. Argentavis was most probably a scavenger, like its modern relatives. Its deep, hooked beak would have been used to tear through the tough hide of dead animals, rather than used to attack live prey. The large, herbivorous mammals that grazed the open plains of Argentina during the Miocene provided a rich food source. But such a large bird was vulnerable to changes in food supply or climate. Argentavis' fate would, therefore, have been closely linked to that of the early mammals of South America. Argentavis and other New World vultures are more closely related to storks than to other birds of prey; in fact, these vultures share a common origin with the storks, diverging from them very early in the Tertiary period.
	Classification:GENUS	Name:Argyrolagus	Age:Late Miocene to Late Pliocene
	Locality:South America (Patagonia)	Size: 16 in/40 cm long	Fossil Name:
	Notes:Just like modern , kangaroo rats and other desert rodents (of which it is no relation), Argyrolagus moved quickly over. open country on its slim 2-toed hindlegs, balanced by its long heavy tail. The head was -somewhat rodentlike, but it had a pointed snout. Enormous eye sockets, which suggest that the animal foraged only at night, were situated far back in the skull. The teeth suggest that it ate desert plants.
	Classification:GENUS	Name:Arnebelodon	Age:Late Miocene
	Locality:North America (Colorado, Nebraska)	Size:10 ft/3 m high	Fossil Name:
	Notes:Amebelodon was a typical, tall "shoveltusker" of the gomphothere family, which roamed the prairies of North America during the Late Miocene. By around 10 million years ago, the forests had given way to vast dry grasslands, an environment best suited to hoofed running animals such as the horses. But the plains were also crossed by many winding rivers in which luxuriant water plants flourished. This was the niche into which Arnebelodon was able to evolve. In body size and general appearance, Amebelodon was similar to the modern elephants, but its skull and tusks were quite different. The flattened tusks of the elongated lower jaw lay side by side, forming a shovel or trough which projected more than 3 ft/ I In to a spadelike cutting edge. The water plants on which Amebelodon fed would have been gripped between the flattened trunk and tusks and ripped from the mud of the river bottom, then pulled up the trough to the mouth by the trunk.
	Classification:GENUS	Name:Arrhinoceratops	Age:Late Cretaceous
	Locality:North America (Alberta and Utah)	Size:18 ft/5.5 m long	Fossil Name:
	Notes:Arrhinoceratops was a close relative of the long-frilled Chasmosaurus (above). But it resembled the short-frilled Triceratops in having a short face, and well-developed brow horns that curved forward over the snout. There was also a modest-sized nose horn. Round openings cut through the bone of Arrhinoceratops' neck frill, thereby reducing its weight. The frill itself had a deeply scalloped margin, set with great bony knobs at wide intervals. The remains of this horned dinosaur are not as common as many others of its family. This may be due to the fact that the animal itself was not abundant, or perhaps it inhabited dry, upland areas where it was less likely to become fossilized.
	Classification:GENUS	Name:Arsinoitherium	Age:Early Oligocene
	Locality:Africa (Egypt)	Size:11 ft 6 in/3.5 m long; 6 ft/1.8 m high at the shoulder	Fossil Name:
	Notes:Arsinoitherium's most memorable features were the 2 massive cone-shaped projections, fused at their bases, which covered the area from the nostrils to midway up its skull. In spite of its appearance, Arsinoitherium was only superficially like a rhinoceros. Its "horns" were in fact hollow, and traces of blood vessels on their surface suggest that they were covered in skin, at least when the animal was young. There were 2 smaller knoblike projections higher on the head that must have looked like a giraffe's skin-covered ossicones. With its complete set of 44 unspecialized teeth forming a continuous series from incisors to last molars, Arsinoitherium was obviously a plant-eater, and probably browsed in the riverside forests. However, the high cross crowns of its cheek teeth suggests it may also have been able to chew tougher vegetation.
	Classification:GENUS	Name:Askeptosaurus	Age:Middle Triassic
	Locality:Europe (Switzerland)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:As with many animals adapted to an aquatic life, the neck and body of Askeptosaurus were long and slim. lots tail was greatly elongated, almost ribbon, like, and accounted for about half the body length. Sinuous movements of the body and tail would have propelled the animal, eel-style, through the water. Its feet, too, would have helped in swimming - they were broad and webbed, and probably used to control steering and braking. Askeptosaurus had long jaws, armed with many sharp teeth. It probably dived deep after its fish prey. This is its eyes deduced from 2 features; s were large, for seeing in the ocean's twilight zone, and they were strengthened by a ring of bony plates, to prevent the eyeballs collapsing under the water pressure at depth.
	Classification:GENUS	Name:Aspidorhynchus	Age: Middle Jurassic to Late Cretaceous
	Locality:Antarctica and Europe (England, France and Germany)	Size:2 ft/60 cm long	Fossil Name:
	Notes:Superficially, Aspidorhynchus looked like the modern gar, or garpike (Lepisosteus) of North America, although there is no evolutionary relationship between them. Like it, Aspidorhynchus must have been a ferocious predator. Its elongated body, protected by thick scales, was perfectly adapted for fast swimming. The symmetrical tail propelled it, the dorsal and anal fins stabilized it, and the paired pectoral and pelvic fins kept it on course. The jaws were studded with sharp, pointed teeth, and the upper jaw was elongated into a toothless guard. Aspidorhynchus and its relatives (the aspidorhynchids, see pp. 18-19) are closely related to the modern teleosts (see pp. 38-41), and most probably shared a common ancestry with them. Only a single species of aspidorhynchid survives today - the bowfin, Amia calva, of North American freshwaters.
	Classification:GENUS	Name:Astrapotherium	Age:Late Oligocene to Middle
	Locality:South America (Argentina)	Size:8 ft/2.5 m long	Fossil Name:
	Notes:Except for its greater size, Astrapotherium was typical of the family as a whole. The head was quite short, with a dome over the forehead created by enlarged air sinuses. The canine teeth continued to grow throughout life and formed 4 tusks. As in a hippopotamus, the larger top pair of tusks sheared against the lower pair. The broad lower incisors protruded, and probably worked against a horny pad in the upper jaw to crop plants. Evidence for a trunk is somewhat contradictory. The nose bones were certainly very short, and opened high on the forehead, which suggest a trunk. Yet there seems to have been no clear reason for a proboscis: Astrapotherium's neck was not particularly short, and its head could easily have reached the ground. It is possible that the "trunk" was really an inflated nose. Astrapotherium had a long, low body with a weak back and legs, the hind legs feebler than the front ones. The feet were small and plantigrade - the weight was borne on the flat of the foot. Taken together, the features seem to indicate that the animal was largely aquatic, wallowing in shallow water and rooting about with its tusks and trunk for water plants. Such a lifestyle and physical structure is reminiscent of the amyndont rhinoceroses found in the northern hemisphere.
	Classification:GENUS	Name:Australopithecus afarensis	Age:Mid Pliocene
	Locality:Africa (Ethiopia and Tanzania)	Size:around 4 ft/1.2 m tall	Fossil Name:
	Notes:The earliest known hominid, dating from around 3.5 million years ago, was Australopithecus afarensis - the "southern ape from Afar." The partial skeletons of this hominid, from the Afar Triangle in northern Ethiopia, match a slightly earlier series of footprints in volcanic ash near Laetoli in Tanzania. When it was excavated in 1974, the first skeleton was nicknamed "Lucy" after a song by the Beatles. The adults were small - not much larger in height and weight than a 6-yearold child today. The skull and face were not unlike a chimpanzee's, with prominent brow ridges, but the brain was a little larger (about 400cc). Lucy's teeth were chipped in front, probably the result of using them to grip with. The hips were quite narrow - which implies that babies were born with relatively smaller heads and brains than modern ones - but otherwise quite humanlike. The legs, too, signify that Lucy was fully bipedal; she walked upright, albeit with a slight stoop, and with very little of the chimpanzee's lurching gait. The footprints confirm that the feet were essentially the same as modern human feet, but without a ball at the base of the big toe. Lucy would have walked flat-footed, with the toes slightly curled in. The combination of ape and human features makes A. afarensis a likely ancestor of the later humans, but the absolute dating of the remains - an important part of the study of human evolution - has been something of a problem. Geological evidence suggests that they are about 3.5 million years old. Lucy and her closest relatives probably became extinct about 2.5 million years ago, having given rise to later australopithecines and modern humans.
	Classification:GENUS	Name:Australopithecus africanus	Age:Late Pliocene
	Locality:African (Ethiopia, Kenya, South Africa, Tanzania)	Size:4 ft 4 in/1.3 m tall	Fossil Name:
	Notes:The skull of an infant specimen of A. africanus - "southern ape of Africa" was unearthed in the Transvaal in 1924. It was largely disregarded by anthropologists of the time, who thought that human origins lay with another fossil found some years earlier in Piltdown in southern England. This latter fossil, which appeared to possess a large brain, was later proved to be a fake. A. africanus is now rightly regarded as a hominid; one which lived from about 3 million to about I million years ago. Even if A. africanus was not our direct ancestor, it was certainly very close. The brain was small by modern standards, being about the same size as a chimpanzee's (up to 400 cc), and the face still had heavy, apelike jaws. The canines were reasonably large, but in other respects the teeth were quite human. Like A. afarensis, it was a slightlybuilt creature, weighing about 65 lb/30 kg, which walked upright. More important than its overall appearance, though, was its lifestyle. Some have claimed that it had moved from woodland to open savannah, and had already developed tools and cooperative hunting techniques, with a gang of individuals hunting down and killing a single animal or chasing away another hunting animal from its kill. Others argue that the evidence is equivocal. The bone "tools" are so ill-formed that they are probably nothing more than the remains of a hyena's meal. Although hunting was probably significant in human evolution, it is likely that plants - including seeds, nuts, fruit, leaves, stems and roots - formed the major part of the diet.
	Classification:GENUS	Name:Australopithecus robustus	Age:Late Pliocene to Early Pleistocene
	Locality: Africa (South Africa and Tanzania)	Size:5 ft 4 in/1.6 m tall	Fossil Name:
	Notes:A probable sideline of human evolution, A. robustus was a very large species of "southern ape" that emerged around 2.5 million years ago, and died out about a million years ago. Apart from its relatively large build (it was still only about 110lb/50kg), the main difference between A. robustus and the other species was its apelike face, massive jaws, and larger brain (about 500cc). Like its relatives, A. robustus seems to have left the forests and taken up a plains-dwelling existence. Almost certainly exclusively vegetarian, A. robustus was the hunted rather than the hunter, since most of the best preserved skeletons come from carcasses that were killed by carnivores. A broken skull of A. robustus has been found with teeth marks that match up exactly to the teeth of a leopard. The very large jaws of A robustus were powered by strong muscles anchored to a crest over the top of the skull, giving rise to one of the early vernacular names for this creature - "nutcracker".
	Classification:GENUS	Name:Bactrosaurus	Age:Late Cretaceous
	Locality:Asia (Mongolia and China)	Size:13 ft/4 m long	Fossil Name:
	Notes:This is the earliest known hadrosaur, and seems to have been intermediate in structure between the 2 types of duckbills. It had a low, flat head with no crest, and a narrow bill (features of the hadrosaurine duckbills), but in build it was like a lambeosaurine duckbill. It most probably represents an ancestral stage in the development of the group. It could have evolved from one of the iguanodont family, such as Probactrosaurus of China
	Classification:GENUS	Name:Bagaceratops	Age:Late Cretaceous
	Locality:Asia (Mongolia)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:This small protoceratopid represents another specialized offshoot from the main evolutionary branch of the horned dinosaurs. It had a squat, heavy body and long tail, supported on solid legs, 5, toed at the front and 4-toed at the back. Bagaceratops possessed several of the features that were to be developed in the later horned dinosaurs. There was a prominent bony ridge at the back of its skull (the precursor of the ceratopids' neck frill); a pair of leaf-shaped projections on either cheek (part of the ceratopids' head shield); and a definite, though short, horn halfway along its snout (anticipating the great horns of the ceratopids). In addition, it had lost its teeth in the upper beak; other members of its family retained these teeth, which is considered a primitive feature. But despite these advanced characteristics, Bagaceratops was probably not the direct ancestor of the horned dinosaurs.
	Classification:GENUS	Name:Barapasaurus	Age:Early Jurassic
	Locality:Asia (India)	Size:49 ft/15 m long	Fossil Name:
	Notes:A field in central India yielded the only sauropod to be found on that subcontinent to date, and also the world's oldestknown sauropod. In build, Barapasaurus followed the general sauropod plan (above). Only the neck and some of the back vertebrae were hollowed out, as a weight-saving adaptation. Its teeth were spoon-shaped and saw-edged, ideal for eating plants.
	Classification:GENUS	Name:Baryonyx	Age:Early Cretaceous
	Locality:Europe (England)	Size:20 ft/6 m long	Fossil Name:
	Notes:Two unusual features made this large, theropod dinosaur quite distinct from any other. First, it had a huge, curved claw, about 1 ft/30 cm long - hence its scientific name Baryonyx, meaning "heavy claw," and its popular nickname of "Claws." However, the claw was not attached to the skeleton, so it is not known whether it was part of the foreor hindfeet. Paleontologists assume that the claw belonged to one of the forefeet, since the forelimbs of this dinosaur were unusually thick and powerful for a theropod, and could therefore have carried such a weapon. In addition, the great size of the animal would have made the claw difficult to wield if it had been on one of the hindfeet. The second peculiar feature of Baryonyx was its skull, which was long and narrow, rather like that of a crocodile. The jaws were armed with a great number of small, pointed teeth, twice as many as a theropod usually possessed. There was also a bony crest on top of the head. The neck was not so flexible as that of other theropods, and could not have been carried in their characteristic S-shaped curve. The habits of this mysterious beast may be surmised from some fish remains that were found with the skeleton. It is possible that Baryonyx hunted on all-fours along riverbanks, hooking fish out of the water with ts long, gafflike claws on the front legs - just as grizzly bears do today.
	Classification:GENUS	Name:Basilosaurus	Age: Late Eocene
	Locality:North America (Atlantic coast)	Size:up to 82 ft/25 m long	Fossil Name:
	Notes:When the remains of this remarkable early whale were first found in the 1830s, they were thought to belong to some kind of dinosaur. This creature, belonging to the same family as Zygo, rhiza (above), must have looked like a great sea-serpent. Indeed its bones were used in a famous sea-serpent hoax about a century ago. Basilosaurus' snakelike body was supported by a backbone of enormously elongated vertebrae. The ribs were short and confined to the front part of the body. The hip bones were still present, about two-thirds of the way down the animal, and the bones of the hindlegs could still articulate with them. However, the limb bones were so small that it is difficult to imagine what use they would have been, or indeed if they showed outside the body at all. Basilosaurus must have swum in the Eocene oceans by undulating its long body and tail. For the cylindrical body to have worked efficiently as a swimming organ, this whale most probably had tail flukes. The head was typical of the early whales, although it was small in proportion to the body. The nostrils were high up on the snout, and the teeth were of different shapes and sizes. The front teeth were pointed and conical, while the back teeth were saw-edged. (An obsolete name for this animal is Zeuglodon, which means "saw toothed.") These large early whales must have hunted fish and squid in deep waters, as do the larger species of modern toothed whale, such as the sperm whale.
	Classification:GENUS	Name:Bernissartia	Age:Early Cretaceous
	Locality:Europe (Belgium and England)	Size:2 ft/60 cm long	Fossil Name:
	Notes:This mesosuchian was tiny in comparison with its relatives. It lived along the shores of the shallow Wealden Lake that stretched from southeast England into Belgium during Early Cretaceous times, some 130 million years ago. Bernissartia led a semi-aquatic life, judging by the 2 types of teeth in its jaws. Those at the front were long and pointed, as if for catching fish, while those at the back were broad and flat, as if for crushing shellfish, or even the bones of dead animals.
	Classification:GENUS	Name:Berycopsis	Age:Late Cretaceous
	Locality:Europe (England)	Size:14 in/35 cm long	Fossil Name:
	Notes:Berycopsis was one of the earliest spinyrayed teleosts (the acanthopterygians) to appear. Today, this group, with an evolutionary history of some 70 million years, is the most successful and varied of all bony fishes, accounting for 40 percent of living species. They range from barracuda and swordfish, to perch, tropical reef fish, flatfish and seahorses. Berycopsis had all the typical features of the group. The first fin ray in the dorsal and anal fin was enlarged into a stout spine, which could be erected for defense (hence the name of the group, "spiny-rayed" fishes). Its pectoral fins were placed high on the side of the body, to better control steering and braking; the pelvic fins had moved forward, to counterbalance the pectorals. Berycopsis' body had a lightweight coat of thin, rounded scales, their surfaces made abrasive by tiny, comblike teeth. And its swim bladder was no longer connected to the throat, and the fish relied on the bladder's own gassecreting and absorbing glands to make it neutrally buoyant.
	Classification:GENUS	Name:Birbalomys	Age:Early Eocene
	Locality: Asia (Pakistan)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Birbalomys is considered by some paleontologists to be the most primitive rodent, one which is probably close to the ancestry of the whole rodent group. So little is known about Birbatomys that the restoration given is highly speculative, but it may have resembled the North African gundis, creatures rather like guinea pigs which today inhabit desert or semi-desert habitats.
	Classification:GENUS	Name:Blastomeryx	Age:Early Miocene to Late Pliocene
	Locality:North America (Nebraska)	Size:2 ft 6 in/75 cm long	Fossil Name:
	Notes:This deerlike creature, not much bigger than a large rabbit, probably looked and lived like the modern chevrotains. Scampering, browsing forest animals, their canine teeth had evolved into long sharp saberlike tusks, useful for rooting up food or for defense. Blastomeryx had no horns. However a late species from the end of the Miocene did have bony bumps on top of the skull, suggesting that horns were evolv, ing; they also showed a reduction in the size of the tusks. This is consistent with the modern rule that deer with tusks have no horns, and vice versa.
	Classification:GENUS	Name:Boreaspis	Age:Early Devonian
	Locality:Spitsbergen	Size: 5 in/13 cm long	Fossil Name:
	Notes:At least 14 species of Boreaspis are known from sandstones laid down in the lagoons of Spitsbergen during the Early Devonian. They differ in the width of their triangular-shaped head shields, and in the length of the bony spine that grew out from the cheek area on either side. The snout was elongated in all species into a bladelike rostrum. Beside its hydrodynamic function, the rostrum was probably used to probe for prey on the muddy lagoon floor.
	Classification:GENUS	Name:Borhyaena	Age: Late Oligocene to Early Miocene
	Locality:South America (Patagonia)	Size:5 ft/1.5 m long	Fossil Name:
	Notes:Some borhyaenids were rather bearlike, with heavy bodies and flat feet. The wolf-sized Borhyaena was typical of this group, but other closely related types ranged from fox-sized creatures to animals as big as bears. These were the main predators of the day. Their prey would have included the plant-eating ungulates that were restricted to South America, The short limbs suggest that Borhyaena was not much of a runner, but probably ambushed its prey. It may also have been a scavenger.
	Classification:GENUS	Name:Bos	Age:Pleistocene to Recent
	Locality:Europe (Britain, Poland), Asia (India) and North Africa	Size:10 ft/3 In long	Fossil Name:
	Notes:This is the genus to which our modern domesticated cattle belong. The ancestor of most of today's cattle was Bos primigenius, better known as the aurochs. It was somewhat larger than most of today's breeds and was first domesticated about 6000 years ago, although it was known to (and hunted by) humans much earlier: the famous cave paintings at Lascaux, in central France, include dramatic and beautiful representations of these great cattle. The aurochs spread during the Pleistocene from its center of origin in Asia, and by the end of the last Ice Age it occupied a vast range in the Old World, from westernmost Europe to easternmost Asia, and from the Arctic tundras to North Africa and India. Despite its success, however, the aurochs disappeared, succumbing to human hunting pressure. It became extinct in Britain by the 10th century AD, and the last surviving aurochsen died in Poland in 1627. Early classifications grouped together the rabbits and hares, which have 2 pairs of upper incisors, with the squirrels, rats and cavies, which have only 1. Certainly their lifestyles and anatomy are similar: all are vegetarian gnawers, and many species in both groups are adapted to life on or underneath the ground. More recently, however, the 2 groups have been separated, in the belief that there is little relationship between them, and that any similarities are the result of an extraordinary degree of convergent evolution. However, our fossil record is still so meagre for the critical early stages of their radiation that we remain uncertain about the relationship between the two orders.
	Classification:GENUS	Name:Bothriolepis	Age:Late Devonian
	Locality:Worldwide	Size:1 ft/30 cm long	Fossil Name:
	Notes:Bothriolepis was a member of the most heavily armored group of placoderms, the antiarchs. These fishes shared a common ancestor with the arthrodires (above), and like many of them, were flattened bottom-dwellers - although antiarchs lived in freshwaters. The head was protected by a short bony shield, which hinged onto a long trunk shield. The pectoral fins of Bothriolepis and its relatives were reduced to a pair of bony-plated spines, which could have played no role in swimming. They articulated with the front edge of the trunk shield via a complex hinge. A joint halfway along their length suggests that they could have been bent, and used like stilts to carry their heavy owner over the river bed. The upturned tail would have produced lift at the rear of the body, keeping the fish's head down while it scavenged in the bottom mud or sand for food particles.
	Classification:GENUS	Name:Brachiosaurus	Age:Late Jurassic
	Locality:North America (Colorado) and Africa (Tanzania and Algeria)	Size:75 ft/23 m long	Fossil Name:
	Notes:Of all the land animals for which a complete skeleton exists, Brachiosaurus is the largest and most massive. Larger sauropod bones have been unearthed recently in western North America (above), and preliminary findings indicate that these dinosaurs may have been 100-130ft/30-40m long. But the re, mains are incomplete, and await de, tailed scientific study. In the meantime, a complete specimen of Brachiosaurus is displayed in the Paleontological Museum at Humboldt University in East Berlin. It is the largest mounted skeleton in existence. Its bones were found in Tanzania, East Africa, by an expedition from Humboldt University in 1908-12. Brachiosaurus was, on average, 7 5 ft/23 m long, and 41 ft/ 12.6 in tall. Its shoulders were 21 ft/6.4 in off the ground; the upper arm bone, or humerus, alone accounted for 7 ft/2.1 m of this height. It weighed an incredible 89 US tons/80 tonnes - almost 3 times the weight of that other giant sauropod Apatosaurus (=Brontosaurus), or the equivalent of 12 modern, adult African bull elephants. The secret of supporting such a massive body lay in the construction of Brachiosaurus' backbone. Great chunks of bone were hollowed out from the sides of each vertebra, to leave a structure, anchor-shaped in cross-section, made of thin sheets and struts of bone. The resulting skeleton was a masterpiece of engineering - a lightweight framework, made of immensely strong, yet flexible, vertebrae, each angled and articulated to provide maximum strength along the lines of stress. Brachiosaurus had a deep, domed head, with a broad, flat snout. The head was tiny in comparison with its body, and the brain cavity was equally small. Pointed, peglike teeth lined the jaws. Two great nasal openings (external "nostrils" were on top of the head above the eyes, as in all other sauropods. Their position originally led paleontologists to think that Brachiosaurus and its other massive relatives spent most of their time submerged in water, browsing on soft weeds, with their nostrils above the surface, breathing in air. But it is now recognized that the pressure exerted by the great depth of water needed to cover the animals would have made breathing difficult, if not impossible. An animal's fleshy nostrils may not necessarily be close to its external nasal openings. Modern elephants, for example, have nasal openings on top of their heads, but they breathe through the fleshy nostrils at the tip of their trunks. This raises the question, did some sauropods have trunks (below)? Another possible function for the large nasal openings of sauropods involves heat regulation; the openings may have been lined with moist, blood-rich skin that helped to keep the animal's brain cool in hot weather. Brachiosaurus' neck was extremely long, making up about half of its height. There were no more neck vertebrae than usual among sauropods (between 12 and 19), but each was elongated to 3 times the length of the back vertebrae. An unusual feature among sauropods - but a characteristic of the brachiosaur family - was that the front legs were longer than the back legs. So, the whole body sloped down from its highest point at the shoulders, as in a modern giraffe, giving the animal's long neck an even greater reach, to tree-top foliage.
	Classification:GENUS	Name:Brachycrus	Age:Early and Middle Miocene
	Locality:North America (Great Plains)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:Brachycrus was a merycoidodont that appeared quite late in North America. It was somewhat smaller than Merycoidodon, and considerably more specialized. The skull and jaw were short indeed, practically apelike - and the eye sockets faced forward. The nostrils were placed far back on the top of the skull, and this suggests that the animai had a short tapirlike trunk. Brachycrus may have used this trunk in sniffing out and manipulating food in the undergrowth.
	Classification:GENUS	Name:Branisella	Age: Early Oligocene
	Locality:South America (Bolivia)	Size:16 in/40 cm long	Fossil Name:
	Notes:This is the earliest-known monkey to have lived on the South American Conti, nent, but little can be said with confidence about Branisella's lifestyle and relationships because the only fossil evidence of its existence are some fragments of jawbone. The teeth were quite primitive, with many tarsierlike features. This would suggest that it evolved from the omomyids farther north. However, some other attributes indicate that Branisella was quite close to the monkeys then living in Africa, so its ancestors may even have reached South America by drifting across the Atlantic from west Africa on floating islands of vegetation.
	Classification:GENUS	Name:Brontops	Age:Early Oligocene
	Locality:North America	Size:8 ft/2.5 m high at the shoulder	Fossil Name:
	Notes:As the Eocene passed into the Oligocene, the brontotheres became very large indeed - larger than any living rhinoceros - and developed the distinctive bony knobs on the snout. Skeletons of Brontops have been found with partly-healed breaks in the ribs, a fact which lends support to the theory that the skull outgrowths were used in fights among males for dominance. The breaks suggest that the animal had received a heavy blow in the flanks from a rival, since no other animals around at that time that could have inflicted such damage. The movement of the ribcage during breathing would have prevented broken bones from knitting together properly. One of the most famous skeletons of Brontops was discovered in rocks that had formed in a bog. The animal had evidently lived in swampy woodland, and had died by becoming swallowed up in the mud.
	Classification:GENUS	Name:Brontotherium	Age:Early Oligocene
	Locality:North America	Size:8 ft/2.5 m high at the shoulder	Fossil Name:
	Notes:The bones of this giant mammal are quite common in the Badlands of South Dakota and Nebraska. The local Sioux Indians had always associated them with the creatures of mythology - the great horses that galloped across the sky producing storms - and so the term "brontothere," "thunder beast," was born. Brontotherium itself was one of the largest - larger than the living rhinoceroses. Its nasal horn was Y-shaped and swept upward higher than the back of the head. The vertebrae at the shoulders had enormous upward-projecting spines. These were evidently used to anchor powerful neck muscles that must have been needed to support the heavy head with its huge, flamboyant ornamenta, tion. There may have been fleshy lips and a prehensile tongue, enabling Brontotherium to select and nibble the juiciest twigs and leaves from the bushes-, the teeth were of relatively simple design and were able to deal only with tender vegetation. Brontotherium seems to have lived, like other brontotheres, in herds that wandered through open scrubby woodlands. They roamed along the foothills of the rising Rocky Mountains - a" intensely volcanic area at that time. Every now and again an eruption would bury herds of Brontotherium in ash, and it is in these volcanic deposits that their skeletons are found today.
	Classification:GENUS	Name:Cacops	Age:Early Permian
	Locality:North America (Texas)	Size:16 in/40 cm long	Fossil Name:
	Notes:Cacops was a member of the dissorophids. This diverse family of temnospondyls arose slightly later than the eryopids (above), and became extinct after them, in the Early Triassic. Many members of this family were fully adapted land-living amphibians. Their heyday came in the Early Permian, when the climate in Euramerica changed from the warm, humid conditions of the Carboniferous to the more and conditions of the Permian. Cacops and its relatives, along with some of the eryopids, were quick to adapt to this drier climate. Cacops is regarded as the amphibian best adapted to life on land. To protect itself, bony plates covered its body, and a row of thick armor ran down the backbone. Its legs were well-adapted for walking on land, and were almost reptilelike in their structure. There was a broad opening (the otic notch) behind each eye. In life, this was covered by a taut membrane which acted as an eardrum to detect airborne sounds.
	Classification:GENUS	Name:Cainotherium	Age:Late Oligocene to Early Miocene
	Locality:Europe (Spain)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Cainotherium was a small rabbitlike animal, with hind limbs longer than the front limbs. The parts of the brain associated with hearing and with smell were well developed, so it probably had long rabbitlike ears and a sensitive nose as well. It must have lived like a rabbit, too, scampering and hopping through the undergrowth, where it bro~'sed on a variety of vegetation. Yet it was clearly an even-toed ungulate. Even at this early stage in its evolution, the limbs were slender, with 2 toes and reduced lateral toes ending in hoofs. Also, unlike the rabbit, it did not have particularly specialized teeth. The full number of mammalian teeth were present. These formed a nearly continuous series with no gap (diastema) between front and cheek teeth. However, the back teeth were quite broad, with 5 cusps, and were welladapted for chewing. Cainotherium and its relatives may have competed with, and lost out to, the early rabbits and hares for the same ecological niches. They were restricted to Europe and left no descendants after the early Miocene.
	Classification:GENUS	Name:Callovosaurus	Age:Middle Jurassic
	Locality:Europe (England)	Size:11 ft 6 in/3.5 in long	Fossil Name:
	Notes:Although this dinosaur is known only from a single thigh bone, this bone shows that Callovosaurus was unlike its contemporary relatives, the hypsilophodonts. It was, in fact, the earliestknown member of the iguanodonts, and presumably was similar in structute and appearance to the later Camptosaurus (below).
	Classification:GENUS	Name:Camarasaurus	Age:Late Jurassic
	Locality:North America (Colorado, Oklahoma, Utah and Wyoming)	Size:up to 59 ft/18 m long	Fossil Name:
	Notes:This ubiquitous sauropod probably roamed in herds over the moist, tropical plains that covered western North America during the Jurassic period. Its heavy, spoon-shaped teeth could have dealt with fibrous plants, such as ferns and horsetails. And it could have reached up to the lower branches of conifer trees, and torn away great mouthfuls of tough, needlelike leaves. Camarasaurus had enormous nasal openings on top of its skull. Their size, together with the animal's short face, has led some paleontologists to specu, late that this sauropod had a trunk, like that of a modern elephant, and used it in the same way. However, other scientists think that the large nasal openings acted as a cooling device for the brain (see Brachiosaurus, above). The remains of juveniles have been found with adult Camarasaurus in the same sequence of rocks (known as the Morrison Formation) in the western USA. This suggests that the young traveled with the herd, maybe on long migrations if the animals were forced to find new feeding grounds. The periodic droughts typical of this tropical Jurassic land could have made such migrations necessary. Another clue to lifestyle is found in the isolated heaps of polished pebbles preserved in the same rocks. These could be the regurgitated stomach stones that many sauropods, including Camarasaurus, swallowed as an aid to grinding up their tough plant food. Many modern birds also swallow stones for the same reason. When the stones have become so worn as to be of little use as digestive aids, they are regurgitated and new ones are found.
	Classification:GENUS	Name:Camciops	Age: Pleistocene
	Locality:North America (California and Utah)	Size:6 ft 6 in/2 m high at the shoulder	Fossil Name:
	Notes:Camelops, another giant of the late Cenozoic and a contemporary of early humans, appears to have been the last camel to have survived on the North American continent. It probably looked very much like the modern Asian camel, but certain parts of its anatomy indicate that it was more closely related to the South American llamas.
	Classification:GENUS	Name:Camptosaurus	Age:Late Jurassic
	Locality:Europe (England and Portugal) and North America (Colorado, South Dakota, Utah and Wyoming)	Size:20 ft/6 m long	Fossil Name:
	Notes:Like Callovosaurus (above), Camptosaurus was a primitive member of the iguanodont family. From the many skeletons of different sizes found particularly in the dinosaur-rich beds of the Morrison Formation in the western USA - Camptosaurus was evidently an abundant dinosaur. Finding it on both sides of today's Atlantic Ocean sup, ports the theory that the continents of North America and Europe were still joined together some 120 million years ago. The skull of Camptosaurus was very different from that of its hypsilophodont ancestors. It was long, low and broad; it was also fairly heavy, since some of the "windows" or gaps between the bones had been closed up. The snout was greatly elongated, and the jaws formed a pronounced toothless beak at the tip. As in many other plant-eating dinosaurs, there was a bony palate that separated the air-breathing passages from the eating area of the mouth. This allowed the animal to breathe and chew at the same time - an important development for all herbivores, since they had to spend most of their time eating in order to fuel their massive bodies. The legs were long and powerful, each with 3 hoofed toes. The thigh bones were massive and slightly curved. The arms were much shorter than the legs, but also equipped with small hooflike nails, so that the animal could use its hands as feet.
	Classification:GENUS	Name:Canis dirus	Age:Pleistocene to Recent
	Locality:: North America (California)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:The genus of dogs called Canis includes the 9 living species of wolves, coyotes, jackals and dogs - both wild dogs and every domestic breed, from Great Dane to Chihuahua. Many more species existed in the past, one of the best known being C. dirus, the dire wolf. In appearance, this prehistoric wolf was much like its modern counterpart, but it was more heavily built. It was probably a scavenger rather than a hunter, taking over the niche of borophagines, such as Osteoborus, after their extinction in the Early Pleistocene. The remains of more than 2000 dire wolves have been excavated from the tar pits of Rancho La Brea, where the city of Los Angeles stands today. About 25,000 years ago, crude oil seeped to the surface here, and its volatile components evaporated, away, leaving behind pools of sticky tar. These pools, disguised by innocent-looking puddles of water on top, trapped unwary animals, such as ground sloths and elephants, as they ventured in to drink. In turn, the panic of the dying animals attracted carnivores, such as the dire wolf and sabertooth cat, Smilodon, and these predators also became enmired. The conditions under which fossilization took place have left a detailed record of life in Pleistocene times. Evidently, the dire wolves and sabertooths engaged in fierce fights, since their bones are often covered with scars inflicted by each other's formidable teeth. More active hunters, such as the contemporary lions and dogs, were rarely trapped in the tar. It seems that these more intelligent animals could appreciate the danger of following their prey into the pools.
	Classification:GENUS	Name:Canobius	Age:Early Carboniferous
	Locality:Europe (Scotland)	Size:3 in/7 cm long	Fossil Name:
	Notes:A new development had occurred in the skull of this tiny fish. The cheek bones and the hyomandibular bones, which attached the upper jaws to the braincase (see p. 21), both became upright. So, the jaws were suspended vertically beneath the braincase (rather than obliquely as in other palaeoniscids). This new at, rangement allowed the mouth to be opened wider, while at the same time the gill chambers behind the jaws were greatly expanded. This innovation affected both respiration and feeding. As the mouth was opened wide, a greater volume of water passed over the gills. More oxygen could be absorbed from the water, which in turn led to increased activity. Canobius could also exploit a rich source of food. Tiny planktonic creatures were carried into its gaping mouth in the surge of incoming water, and w ere caught on the minute teeth that lined its jaws and gills.
	Classification:GENUS	Name:Casea	Age:Early Permian
	Locality:Europe (France) and North America (Texas)	Size:4 ft/1.2 m long	Fossil Name:
	Notes:The caseids, represented by Casea, were the last family of pelycosaurs to evolve, in Early Permian times. They became the most abundant of the plant-eating pelycosaurs, and thrived almost to the end of the Permian. Casea was small in comparison with some of its relatives, which reached lengths of 10 ft/3 in and weights of more than 1320 lb/600 kg. They all had deep, bulky bodies, in which the rib cage was enormously expanded to accommodate the long, plant-digesting gut. Their square-shaped heads were tiny, with huge synapsid openings at the back and large nasal openings at the front. Caseids were unique among pelycosaurs in having no teeth in the lower jaw. Those in the upper jaw were thick, blunt pegs with wavy edges, like those of modern herbivorous lizards. In addition, numerous small teeth studded the palate. Such a dentition suggests a diet of tough plants, such as ferns and horsetails.
	Classification:GENUS	Name:Cearadactylus	Age:Early Cretaceous
	Locality:South America (Brazil)	Size:13 ft/4 m wingspan	Fossil Name:
	Notes:Cearadactylus' jaws were expanded at the tip (rather like those of the modern gavial crocodile), and several large teeth protruded around the edges. These interlocked when the mouth forming a trap for slippery fish prey, which was then easily dealt with by the numerous conical teeth lining the jaws.
	Classification:GENUS	Name:Centrosaurus	Age:Late Cretaceous
	Locality:North America (Alberta and Montana)	Size:20 ft/6 m long	Fossil Name:
	Notes:This horned dinosaur was a typical member of the short-frilled group. (It used to be known by the name Monoclonius.) A long horn surmounted the snout of Centrosaurus (in some species, it curved forward), and two short horns rose above its eyes from the brow. The neck frill stood up from behind the head, and was fringed with spines. There were 2 large openings on either side of the frill, which in life were covered over with skin, as was the rest of the frill. These holes reduced the weight of the bony structure, and their edges provided additional attachment points for the powerful jaw muscles. A strong ball-and-socket joint connected the head to the neck. This was placed well forward in the skull, about under the eye region, so that the weight of the heavy frill at the back of the head was balanced by the great horn on the front. This mobile joint ensured that Centrosaurus could turn its massive head easily and quickly. This was important for such a slow-moving animal, since its head weapons were its only defense. Some of the neck vertebrae were fused together, to increase its strength, and the muscles of the forequarters were powerfully developed.
	Classification:GENUS	Name:Ceratosaurus	Age:Late Jurassic
	Locality:North America (Colorado and Wyoming)	Size:20 ft/6 m long	Fossil Name:
	Notes:This "horned lizard" had a heavier skull than other carnosaurs because of the presence of a pair of bony ridges above its eyes, and a low crest, or horn, on its snout. The function of the horn remains a mystery, although various suggestions have been put forward as to its use. It could have been used for defense, but it seems too small and not well placed for a fight. Or it could have been for sexual display, with only the males possessing it and using it in the ritualistic, headbutting battles probably engaged in to decide hierarchy among the group. Ceratosaurus was evidently an active predator. It had massive jaws, armed with sharp, curved teeth. The short arms had 4 powerful, clawed fingers, and the long legs had 3 clawed toes on each foot. An unusual feature was a narrow row of bony plates running down the center of its back and tail, giving the appearance of a serrated crest. This could have been a device for losing heat from the body, similar to the back fin of Spinosaurus (see p. 120) or the plates of Stegosaurus (see p. 156). Footprints thought to be those of Ceratosaurus have been preserved in the dinosaur-rich rocks of the Morrison Formation in the western USA. These ancient trackways suggest that these dinosaurs moved in groups, and maybe cooperated in packs to bring down the larger dinosaurs.
	Classification:GENUS	Name:Cerdocyon	Age:Pleistocene
	Locality:South America (Argentina)	Size:2 ft 6 in/80 cm long	Fossil Name:
	Notes:The dog family evolved in North Amer, ica throughout the Tertiary period. The animals that belonged to this group could not reach South America because the 2 continents were separated by a sea. Then, toward the end of the Tertiary, in Pliocene times (about 5 million years ago), the Central American land bridge was reestablished, and animals could migrate southward. The dogs crossed into South America in the Early Pleistocene, some 2 million years ago, and the early fox Cerdocyon was among the invaders in this trek southward. Two million years later, Cerdocyon lives on in the form of the common zorro or crab-eating fox, Cerdocyon thous, found from Colombia to northern Argentina. Crabs are only part of the diet of this omnivorous nighthunter. It also eats rats and mice, frogs and insects, fruit and carrion, and any creature's eggs it can find. Its Pleistocene relative probably pursued the same opportunistic lifestyle.
	Classification:GENUS	Name:Ceresiosaurus	Age:Middle Triassic
	Locality:Europe	Size:13 ft/4 m long	Fossil Name:
	Notes:The toes of Ceresiosaurus were much longer than those of most other nothosaurs. In fact, the animal exhibited the phenomenon of hyperphalangy, in which the number of bones (phalanges) in each toe is increased. Longer toes mean longer feet, and Ceresiosaurus had 2 pairs of paddlelike flippers. These would have been efficient swimming organs, and anticipated the great, oarlike limbs of the advanced swimmers of the Jurassic period, the plesiosaurs (see pp. 74-77). Ceresiosaurus swam by undulating its long, sinuous body and tail from side to side. The bones of the forelegs were more massive than those of the hindlegs, suggesting that the front flippers played more of a role in swimming, maybe for effective steering and braking.
	Classification:GENUS	Name:Cetiosaurus	Age:MiddleJurassic to LateJurassic
	Locality:Europe (England) and Africa (Morocco)	Size:up to 60 ft/18.3 m long	Fossil Name:
	Notes:Bones of this huge sauropod were discovered in 1809 in Oxfordshire in southern England, 32 years before the word "dinosaur" had been coined. People thought the bones belonged to some great marine animal, hence the name Cetiosaurus, or, "whale lizard." Others thought the bones came from some huge crocodile. It was not until the remains of a similar sauropod, Haplocanthosaurus, were found, in the Late Jurassic rocks of Colorado in western North America, that the true nature of the beast was appreciated. Cetiosaurus was massively built, but with a shorter neck and tail than usual among sauropods. It may have weighed over 10 US tons/9 tonnes. The backbone was a solid mass, since the vertebrae were hardly hollowed out at all. A skeleton unearthed in Morocco in 1979 revealed the size of the animal. The thigh bone alone was over 6ft/1.8m long, and one of the shoulder blades measured over 5 ft/ 1. 5 m in length. The amount of plant food needed to power such great limbs must have been enormous.
	Classification:GENUS	Name:Cetotherium	Age:Middle to Late Miocene
	Locality:Europe (Belgium and USSR)	Size:13 ft/4 m long	Fossil Name:
	Notes:Cetotherium belonged to a family of early baleen whales which evolved in the Late Oligocene and reached their peak during the Miocene, some 15 million years ago. It looked strikingly similar to the modern gray whale of the North Pacific, although it was less than a third of its length. Its baleen plates were probably quite short, although this is difficult to deter, mine, since baleen, like horn and hair, does not fossilize. However, the skulls retain the marks of blood vessels which supplied the baleen during life, and much can be told from their traces. Cetotherium and its relatives were probably preyed upon by a species of great white shark Carcharodon which, judging by the size of the teeth that are often found fossilized, reached a size approaching that of a small whale. Most ungulates (the word means "hoofed animals") are large plant-eaters which either root and browse among vegetation or crop grass. Early rooters and browsers were a diverse group of ungulates most of which ate leaves, shoots and roots, though some evolved into scavengers. It was from these early ungulates that more specialized grazers evolved, among them hoofed runners such as horses, cattle and deer. They rose to dominance during the Miocene period, moving out of the forest to exploit the new feeding opportunities in the developing grasslands. Some early ungulates were for many years regarded as members of the primitive order of carnivorous mammals, the creodonts. This confusion is an indication of the very generalized nature of the mammals at the end of the Cenozoic era.
	Classification:GENUS	Name:Champsosaurus	Age:Late Cretaceous to Eocene
	Locality:Europe (Belgium and France) and North America (Alberta, Montana, New Mexico and Wyoming)	Size:5 ft/1.5 m long	Fossil Name:
	Notes:With its long, narrow jaws, filled with fine, pointed teeth, Champsosaurus could easily have been mistaken for the modern gavial of India, a close relative of the crocodile. However, although ,both animals are diapsid reptiles, they are not closely related to each other. Their similarity is explained by the phenomenon of convergent evolution, in which adaptation to life in a particular environment leads unrelated animals to adopt the same body shape, and often the same behavior. Champsosaurus lived in the rivers and swamps of Europe and western North America throughout the Late Cretaceous and Early Tertiary periods. It probably swam by lateral undulations of its sinuous body and tail, holding its legs tight against the flanks for a more streamlined effect - the same swimming method seen in modern crocodiles and marine iguanas. This reptile was a fish-eater with extremely powerful jaws, judging by the great width of the skull behind the eyes, which would have provided a large area which jaw muscles could attach.
	Classification:GENUS	Name:Chapalmalania	Age:Late Pliocene
	Locality:South America (Argentina)	Size:5 ft/1.5 m long	Fossil Name:
	Notes:The procyonids were among the mammals that traveled south from North America via the Central American land bridge. Once in South America, they evolved into a number of specialized forms. Chapalmalania was a gigantic raccoon that must have looked rather like the modern giant panda. It was so large that its remains were at first thought to be those of a bear. Like the panda, it doubtless had a very specialized diet, probably relying on some local plant on the mountainsides for much of its food. Its similarity to a giant panda is an example of convergent evolution.
	Classification:GENUS	Name:Chasmatosaurus	Age:Early Triassic
	Locality:Africa (South Africa) and Asia (China)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:Chasmatosaurus (formerly named Proterosuchus) is the earliest well-known thecodontian. It looked rather like a modern crocodile, and probably behaved in much the same way. Its robust limbs, each with 5 toes, were angled out horizontally from the body, resulting in a sprawling, lizardlike gait. Although Chasmatosaurus could walk on land, it probably spent most of its time in rivers, swimming after its fish prey using sinuous movements of the long tail and body. Its jaws were well equipped with sharp, backwardly curved teeth, each set in a shallow socket; the upper jaw turned down sharply at its tip. There were also teeth on the palate - a primitive feature, lost in later thecodontians.
	Classification:GENUS	Name:Chasmosaurus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:17 ft/5.2 m long	Fossil Name:
	Notes:Chasmosaurus was a typical long-frilled type of horned dinosaur. Its skull was quite long and narrow, with a pair of long, upwardly curved horns on the brow and a single, shorter horn on the snout. The bony frill, however, was enormous, stretching from the back of the skull to cover the neck and upper shoulders. Its margin was decorated with bony spikes and knobs. The 2 openings on either side of the frill were so large that the frill itself provided a mere framework surrounding these great holes. So, although the bony frill was a vast size, it was lightweight, and allowed the head to be moved easily. This spectacular frill was undoubtedly a display structure. The great head area that it presented would have acted as a warning to attackers, whether predators or rival males, or as a sexual signal to females, especially when the head was moved about. It is possible that all the males in a herd would cooperate in a group-threat display, forming a ring around the young in times of danger, and shaking their great beads and neck frills at the enemy. Some paleontologists think that these horned dinosaurs could run quite quickly when necessary. This is suggested by certain features of their anatomy. The shoulder blades, for example, were not firmly fixed to the rest of the skeleton, and there were no collar bones to keep them in place. So, the whole shoulder girdle would have moved back and forth with the forelegs, helping the animal to run quickly. In contrast, the hips were firmly fixed in position, attached to the backbone by 8 sacral vertebrae, which provided a strong, solid anchor for the heavy hindquarters.
	Classification:GENUS	Name:Cheirolepis	Age:Middle to Late Devonian
	Locality: Europe (Scotland) and North America (Canada)	Size:up to 22 in/55 cm long	Fossil Name:
	Notes:Cheirolepis was a fast-moving freshwater predator and one of the largest members of the palaeoniscids, the first ray-finned fishes to evolve (above), Its streamlined body was encased in a heavy coat of small, rectangular (rhomboid) scales, arranged in diagonal rows - just like those of the spiny sharks. (The scales were covered with a unique type of enamel called ganoine, which gives the palaeoniscids their collective name of "ganoid" fishes.) A row of large scales stiffened the top side of the tail's elongated upper lobe, enhancing its powerful flexing movements during swimming. These scales were a unique feature of all early ray-finned fishes. The upturned tail tended to drive the fish downward in the water. So to counteract this, the paired pectoral and pelvic fins on the underside functioned as hydrofoils, elevating the body at the front. Stability was provided by the large dorsal and anal fins. Like all palaeoniscids, Cheirolepis had large eyes, and probably hunted by sight. Its jaws were equipped with many sharp teeth, and could be opened wide to engulf prey two-thirds its own length.
	Classification:GENUS	Name:Chriacus	Age:Early Paleocene to Early
	Locality:North America (Wyoming)	Size:3 ft/1 m long	Fossil Name:
	Notes:This agile climbing animal may have scampered about in the tropical forests of Early Tertiary North America, sniffing out and eating insects, small animals and fruit, It had powerful limbs, versatile joints and a semi-prehensile tail. Chriacus had plantigrade feet - the full foot was placed on the ground rather than just the toes - and there were long claws. The forelimbs may have been used for digging, but the hind limbs were definitely those of a climbing animal.
	Classification:GENUS	Name:Cistecephalus	Age:Late Permian
	Locality:Africa (South Africa)	Size:13 in/33 cm long	Fossil Name:
	Notes:Dicynodonts adapted to many lifestyles. Some were semi-aquatic, while others browsed in the coniferous forests. Some, such as Cistecephalus, lived underground. This creature had a wedge-shaped, flattened head, a short body and strong, stumpy forelimbs with broad toes, like those of a modern mole. It probably used its powerful limbs to dig into the soil to find worms, snails and insects.
	Classification:GENUS	Name:Cladoselache	Age:Late Devonian
	Locality:North America (Ohio)	Size:up to 6 ft/1.8 m	Fossil Name:
	Notes:Remains of shark scales are known from the Late Silurian and teeth from the Early Devonian. But it is only in the Late Devonian that recognizable specimens are found. Cladoselache has been remarkably well fossilized in the Cleve, land shales of Ohio, USA. The fleshy outline of its body has been imprinted in the rocks, and even traces of its skin, muscles and kidneys. Cladoselache had a streamlined torpedo-shaped body, with 2 equal, sized dorsal fins; a pair of large pectoral fins; a pair of smaller pelvic fins; a large tail shaped like a half-moon, with equal lobes, and a pair of horizontal keels at its base. Its head was blunt, its eyes large and 5 to 7 gill slits opened behind its toothed jaws. Superficially, the description of this ancient shark, that cruised the open seas 400 million years ago, is strikingly similar to that of a modern oceanic shark, such as the infamous Great White. The main differences are that the modern shark has a pointed snout, a high first dorsal fin, a tail in which the upper lobe is considerably longer than the lower lobe, and an additional fin the anal fin. Like many early sharks, Cladoselache had a spine in front of each dorsal fin. The spines were made of toothlike dentine and probably skin-covered during life, since they are not coated in the protective layer of enamel seen in later sharks. Another unusual feature of Cladoselache is the lack of scales on its body. The only scales were concentrated round the eyes and along the margins of the fins. Besides being a powerful swimmer, Cladoselache was obviously a formidable carnivore. Its mouth was filled with sharp, pointed teeth, each with a long central cusp or projection, flanked by several smaller cusps. The seas of the Late Devonian teemed with prey squid, crustaceans, small jawless fishes, and early bony fishes.
	Classification:GENUS	Name:Cladosictis	Age:Late Oligocene to Early Miocene
	Locality:South America (Patagonia)	Size:2 ft 6 in/80 cm long	Fossil Name:
	Notes:Cladosictis was a primitive carnivorous marsupial which may have resembled an otter in shape and size, with a long body and tail and short limbs. It probably scampered through the undergrowth, seeking out, chasing and catching small mammals and reptiles, and swam in rivers after fish. It may even have eaten reptiles' or birds' eggs and insects. The tooth pattern was similar to that of carnivorous placental mammals. The teeth consisted of incisors at the front for holding prey, followed by pointed canines for killing it, and meat-shearing (carnassial) premolars and molars at the back.
	Classification:GENUS	Name:Claudiosaurus	Age:Late Permian
	Locality:Madagascar	Size:2 ft/60 cm long	Fossil Name:
	Notes:Claudiosaurus was a long-necked, lizardlike animal, whose lifestyle could be compared to that of the modern marine iguana. Claudiosaurus probably spent m uch of its time resting on rocky be aches, warming up its body so that it could go foraging. It would have fed underwater, poking its long, flexible neck and small head in among the seaweeds to find suitable animals and plants. When it swam, its fore- and hindlegs would have been folded against the body to give a more streamlined shape, and offer less resistance to the water. The main propulsive force came from sideways-undulations of the rear body and long, narrow tail. There was quite a lot of cartilage in the skeleton of Claudiosaurus. This suggests that the animal relied on the buoyancy of the water to give it support. Also, the breast bone, or sternum, was neither well developed nor ossified, as it is in true terrestrial animals, where it braces the ribs apart on the underside of the body as an adaptation to walking. The sternum in Claudiosaurus, therefore, suggests that its limbs were not well adapted for moving on land.
	Classification:GENUS	Name:Climatius	Age:Late Silurian to Early Devonian
	Locality:Europe (UK) and North America (Canada)	Size:	Fossil Name:
	Notes:The name "spiny shark" seems particularly appropriate for this fish. Its tiny body was crowded with spines and fins. Two large dorsal fins rose from the back, each supported in front by a stout bony spine, superficially embedded in the skin. There was a large anal fin and spine at the back, and a pair of large pectoral fins with spines at the front. The underside of Climatius' body bristled with spines, but no fins. There was a pair of pelvic spines and 4 pairs of belly spines. Climatius was obviously an active swimmer, to judge by its stabilizing fins and the powerful, sharklike tail, with its large, upturned upper lobe. Like many other acanthodians, it had no teeth in its upper jaw, but there were whorls of small teeth in the lower jaw, continually replaced as they were being worn another sharklike feature. Its large eyes suggest that sight was the chief sense used for locating prey, and it probably fed on crustaceans and fish fry in midwater and at the surface. Its swimming agility and the tightfitting armor of bony scales must have protected Climatius from attack by larger fish and predatory invertebrates , such as squid. The 15 fin spines that arrayed its body were its chief defense, making it extremely awkward to swallow.
	Classification:GENUS	Name:Cobelodus	Age:Middle to Late Carboniferous
	Locality:North America (Illinois and Iowa)	Size:up to 6 ft 6 in/2 m long	Fossil Name:
	Notes:This strange-looking shark had a bulbous snout and a humpbacked profile, with only one dorsal fin on its back, set far to the rear, above the pelvic fins. It also had remarkably large eyes, which could suggest that it hunted in deep, dark waters for crustaceans and squid. One of the cartilaginous rays that supported the pectoral fin was drawn out on each side into a whiplash, about 1 ft/30 cm long. These appendages were obviously movable, since they were jointed along their length.
	Classification:GENUS	Name:COCCOSWUS	Age:Middle to Late Devonian
	Locality:Europe (Scotland and USSR) and North America (Ohio)	Size:16 in/40 cm long	Fossil Name:
	Notes:Coccosteus was a fast-moving hunter and scavenger of the seabed. Its smooth, streamlined body (devoid of scales), paired fins, upturned tail and stabilizing dorsal fin made it a powerful swimmer. It must also have been an aggressive carnivore, due to improvements in the jointing system of its neck. Not only were the head and trunk shields hinged externally, as in Qroentandaspis (above); an internal joint had also developed between the neck vertebrae and the back of the skull, enabling Coccosteus to tilt its head back farther. Thus, it could attain an even wider gape than its relative. Its jaws were also longer, so extending its predatory range. Another advantage of this jointedneck system was that the up-and-down movement of the head would help to pump water through the gill arches, which were expanded when the mouth was opened. Coccosteus probably supplemented its diet by swallowing great mouthfuls of mud; the organic matter contained in it was digested and the remainder expelled as faeces.
	Classification:GENUS	Name:Coclurus	Age:Late Jurassic
	Locality:North America (Wyoming)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:Like all members of the coelurid family, Coelurus had a small, low head (only about 8 in/20 cm long), and the hollow, birdlike bones that characterized all the early dinosaurs. This active predator lived in the forests and swamps of North America where prey was abundant. Its hands, with their 3 clawed fingers, were long and strong, designed for grasping the flesh of small animals like lizards, flying reptiles and mammals.
	Classification:GENUS	Name:Coelodonta	Age:Pleistocene
	Locality:Europe (Britain) and Asia (eastern Siberia)	Size: 11 ft/3.5 m long	Fossil Name:
	Notes:Coelodonta had its origins in the Pliocene of eastern Asia, from where it migrated into Europe (but not into North America) and became the wooly rhinoceros of the Ice Age. Coetodonta had a pair of huge horns on its snout, the front one growing to lengths of over 3 ft/ I In in old males. Like the wooly mammoth, Coelodonta's massive body and shaggy coat allowed it to withstand the harsh conditions of the tundra and steppe that bordered the great glaciers of the Northern Hemisphere. Although normally hair does not fossilize, the presence of the shaggy coat is known because of corpses found preserved in frozen gravels in Siberia. There are eye-witness accounts too. Early humans hunted this great beast, and depicted it on the walls of caves in southern France 30,000 years ago.
	Classification:GENUS	Name:Coelophysis	Age:Late Triassic
	Locality:North America (Connecticut and New Mexico)	Size:8-10 ft/2.4-3 m long	Fossil Name:
	Notes:The appearance of this comparatively large coclurosaur is well known from a find made in 1947 at Ghost Ranch in New Mexico. Here, a number of skeletons of different sizes were massed together, about a dozen of them complete. There were very young individuals (maybe just hatched) and adults, ranging in length from 3 to 10 ft/ I to 3 In. Finding all these animals together in one spot suggests that they lived as a group, and were all overcome at the same time. This early dinosaur must have been a ferocious hunter - it was built for speed. Its slender, hollow-boned body probably weighed less than 50 lb/23 kg. The neck, tail and legs were long and slim, the tail making up about half the body length. The long, narrow head was armed with many sharp teeth, each with a cutting, serrated edge. The birdlike feet had 3 walking toes with sharp claws. There were 4 fingers on each hand, though only 3 were strong enough to grasp prey. It is thought that Coelophysis roamed the upland forests, hunting in packs close to streams and lakes. Among their prey would have been the small, shrewlike mammals that bad evolved towards the end of the Triassic period. Two of the adult skeletons found in New Mexico contained the bones of tiny Coelophysis in their body cavities. Initially, paleontologists thought that this meant Coelophysis gave birth to live young, rather than laying eggs like most other reptiles. But the hip bones proved too narrow for this to be the case. The conclusion seems to be that this dinosaur was cannibalistic.
	Classification:GENUS	Name:Coelurosauravus	Age:Late Permian
	Locality:Madagascar	Size:16 in/40 cm long	Fossil Name:
	Notes:This early reptile was highly adapted for gliding through the air, and probably looked similar to the modern lizard known as the flying dragon, Draco volans, of Southeast Asia. The ribs of Coeturosauravus were greatly elongated on each side of its short body. Flaps of skin would have connected the ribs, to form a pair of "wings" with a total span of about 1 ft/30 cm. This reptile probably lived in forests, like the modern flying dragon, and glided from tree to tree, feeding on insects. Its legs would have been held out from its body as it glided, its feet spread wide to offer resistance to the air, and hence slow its descent. The skull of Coelurosauravus was con, siderably lighter than that of other early diapsids. The openings for the eyes were huge, and there was a wide frill devel- oped from the bones at the back of its head, presumably to make it more aerodynamic.
	Classification:GENUS	Name:Compsognathus	Age:Late Jurassic
	Locality:Europe (Germany and France)	Size:2 ft/60 cm long	Fossil Name:
	Notes:This tiny, 2-legged creature, with the unlikely name of "pretty jaw," probably weighed no more than 8 lb/3.6 kg, and stood no taller than a chicken. Compsognathus must have been a swift hunter, since the bones of a tiny lizard were found in the abdominal cavity of the specimen unearthed in Germany. The whole body was designed for speed. It had the typical hollow bones of a coelurosaur; a long neck for good stretch; an even longer tail for balance; short, grasping arms with only 2 pincer, like fingers; and slender legs with long shins, birdlike feet and 3 clawed toes on each. (A tiny fourth toe pointed backward.) In fact, Compsognathus is similar in structure to the first known bird, Arch, aeopteryx (see p. 176). The two creatures were contemporaries, both living during Late Jurassic times among the wooded islands and lagoons of today's southern Germany.
	Classification:GENUS	Name:Coryphodon	Age:Late Paleocene to Middle
	Locality:Widespread in North America, Europe and eastern Asia	Size:7 ft 6 in/2.25 m long	Fossil Name:
	Notes:Coryphodon was a large animal with canine tusks rather like those of a hippopotamus. These were especially welldeveloped in the male. Like a hippopotamus, too, Coryphodon probably lived in swamps and marshes, where it may have uprooted plants with its tusks. The 2 prominent cross crests on its molar teeth suggest that Coryphodon browsed on jungle vegetation. The upper section of the leg was longer than the lower, which would have provided the strength needed to support a massive body but could not have been suited to fast running. Coryphodon's brain was very small and, at 34'oz/90gm per 1100lb/500kg, probably represented the smallest ratio of brain to body weight in any mammal.
	Classification:GENUS	Name:Corythosaurus	Age:Late Cretaceous
	Locality:North America (Alberta and Montana)	Size:30 ft/9 m long	Fossil Name:
	Notes:A spectacular semicircular crest decorated the head of this large, North American duckbill, which weighed almost 5 US tons/4.5 tonnes. The crest rose steeply from just in front of the animal's eyes into a tall, narrow fan shape (about 1 ft/30 cm high) that curved down to the back of the head. Several sizes of crest have been found in different specimens of Corythosaurus. This could reflect different species of this duckbill, or more likely, it could show different growth stages of the same species, with juvenile specimens having much smaller crests than adults. There may even have been a size difference between the sexes, with full-grown males having the largest crests. Corythosaurus was a typical member of the lambeosaurine group of hadrosaurs - those cluckbills with hollow crests on their heads. (Solid head crests characterized the hadrosaurine duckbills, see pp. 146-149, 150, 152.) As a group, the hollow-crested types seem to have evolved in North America, and been largely confined to the western part of that continent. Some species have also been found in eastern Asia, which fact lends support to the theory that western North America and eastern Asia were joined together in Late Cretaceous times as one landmass, "Asiamerica," and surrounded by shallow continental seas (see pp. 12-13). The domed crest was made up of the greatly expanded nasal bones. The hollows inside the crest were the actual nasal passages, which ran up into the crest and looped back down into the snout. Several theories have been proposed for such an arrangement, some of them more likely than others. The old notion, for example, that hadrosaurs were aquatic animals, led to the belief that the crest, with its series of hollow tubes, was some kind of snorkel, which allowed the animal to breathe air while its mouth and nostrils were submerged. Another theory stated that the crest acted as an air reservoir, so that the duckbill could draw on its supply while swimming or feeding underwater. It is now known that the cluckbills were well-adapted land animals. They were also gregarious and lived in herds, browsing in the forests on tough pine needles, magnolia leaves, seeds and fruits of all kinds. When threatened by predators such as Tyrannosaurus, they could sprint away on 2 legs; they may even have taken to water to escape. Several more likely explanations exist for the hollow crest, and it is quite possible that it served some or all of the proposed functions. First, the hollow crest with its convoluted tube system could have been used as a vocal re, sonator - like the pipe of a trombone - to produce sounds for communication with the rest of the herd. These sounds could have been made for a variety of purposes - to warn other members in the herd of danger, to win a mate or discourage a rival, and for species-recognition between groups. The results of recent research in the USA seem to support this theory. An exact model of a lambeosaur's crest was constructed, and experiments show that these cluckbills could have produced a kind of foghorn sound from such a structure. These booming, resonant notes would have been heard over wide distances, and provided these forest, dwellers with an effective means of communicating between themselves and other herds. The postulated inflatable nasal sacs on the faces of the flat-headed, solid-crested cluckbills (in the hadrosaurine subfamily) probably served the same purpose. Another theory proposes that the long air passage within the hollow crest could have served as a cooling system. Its surface may have been lined with a moist membrane, evaporation from which would have reduced the temperature of the surrounding tissue. This would have helped to cool down the animal when it was browsing in the open under the hot sun, or after a strenuous flight from a predator. A third theory suggests that the hollow crest somehow enhanced the animal's sense of smell, so helping it to find food, detect the approach of danger and keep with the herd. A primitive-looking crested duckbill was found in Montana after the discovery of Corythosaurus, and named Procheneosaurus. Its crest was much smaller than that of Corythosaurus, but it contained the same, typical S-shaped air passage. Some paleontologists think that this creature is possibly the most primitive of the hollow-crested duckbills. Others, however, believe it to be simply a juvenile specimen of Corythosaurus itself.
	Classification:GENUS	Name:Crusafontia	Age:Early Cretaceous
	Locality:Europe (Portugal)	Size:4 in/10 cm long	Fossil Name:
	Notes:The dryolestid Crusafontia is known only from a few teeth. The reconstruction on p. 199 is based on a relatively complete skeleton of another member of the family from the Late Jurassic of Portugal. It probably resembled a tiny squirrel, living in trees and feeding on fruit, nuts and seeds. The long tail may have been prehensile, and the bones of its hip girdle suggest that it may have reproduced the way a marsupial does giving birth to very immature young and suckling them in a pouch for the first few weeks of life.
	Classification:GENUS	Name:Cryptocleidus	Age:Late Jurassic
	Locality:Europe (England)	Size:13 ft/4 m long	Fossil Name:
	Notes:Cryptocleidus and other members of its family retained the same moderately long neck proportions as Plesiosaurus. But they evolved a large number of very sharply pointed curved teeth which intermeshed when the jaws were closed. This arrangement formed a fine trap for holding very small fishes or shrimps. Like other Late Jurassic plesiosaurs, Cryptocleidus had perfected the trans, formation of the limbs into flippers by greatly increasing the number of bones in each of the 5 digits to produce a long, flexible paddle.
	Classification:GENUS	Name:Ctenurella	Age:Late Devonian
	Locality:Australia (Western Australia), and Europe (Germany)	Size: 5 in/13 cm long	Fossil Name:
	Notes:Ctenurella was a small, naked placoderm (one of the ptyctodontids). Its only armor was developed on top of its head and in a band around the shoulder girdle. It had 2 dorsal fins, one upright and the other long and low. Large, paired pectoral and pelvic fins stabilized it from below, and the tail tapered to a whiplash. This small placoderin had crushing tooth plates in its jaws, the upper bones of which were firmly fused to the braincase. It fed on the seabed, grinding up shellfish and sea urchins. It could obviously swim also, to judge by its hydro, dynamic shape and paired fins. Here again is an example of convergent evolution. As with the raylike rhenanids (above), Ctenurella and its relatives had evolved a body design that was to endure in a later group of cartilaginous fishes - the chimaeras or ratfishes (see p. 29). These placoderms even had the penislike claspers developed in the males of the cartilaginous group.
	Classification:GENUS	Name:Cuvieronius	Age: Pliocene to Recent
	Locality:North America (Arizona, Florida) and South America (Argentina)	Size:9 ft/2.7 m. high	Fossil Name:
	Notes:Cuvieronius was named for the great French comparative anatomist and founder of paleontology, Baron George Cuvier (1769-1832). A fairly small gomphothere, Cuvieronius' most remarkable feature was its tusks, which were spir' ally twisted like those of a narwhal. We do not usually associate the South American continent with elephants. However, remains of Cuvieronius have been found in mountainous areas of both North and South America, a fact reflected in its synonym Cordillerion "the one from the mountain range." Cuvieronius evolved in western North America at the end of the Miocene, and migrated to South America during Pleis, tocene times, around 2 million years ago. It spread from the grassy pampas in the east to the heights of the Andes in the west, reaching as far south as Argentina. It was hunted to extinction, probably as recently as AD 400.
	Classification:GENUS	Name:Cymbospondylus	Age:Middle Triassic
	Locality:North America (Nevada)	Size:33 ft/10 m long	Fossil Name:
	Notes:This large ichthyosaur was one of the least fishlike of the group. The body and tail made up most of its length. There was no fin on its back nor on its tail, features that were to develop in later ichthyosaurs. However, it did have the typical long, beaklike jaws, armed with pointed teeth - the sign of a fish-eater. The limbs of Cymbospondylus were short, and looked more like the fins of fish than the paddles of later ichthyosaurs. They would not have been effective for swimming, so they were probably used to control steering and braking. The main propulsive force must, therefore, have come from lateral undulations of the long body.
	Classification:GENUS	Name:Cynodesmus	Age:Late Oligocene to Early Miocene
	Locality:North America (Nebraska)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:Cynodesmus was one of the first canids that actually looked like a modern dog. It was roughly the size and shape of the coyote, Canis latrans, of today's North and Central America. Its face, however, was shorter (the long snout of typical dogs was to come much later in their evolution), and its body was still quite long, with a heavy tail. Cynodesmus' legs were quite doglike, but they were not yet as efficient for running as those of modern dogs. The open grasslands of North America had not formed at this time; their develop, ment encouraged the evolution of fastmoving grazing mammals, which in turn led to the rapid evolution of swiftfooted hunters such as dogs. There were still 5 toes on each of Cynodesmus' feet, although the first toes were smaller than the rest. Its claws were narrow and partially retractable, like those of a cat, rather than the thick, blunt, weight-bearing structures that developed in later dogs. It was probably Cynodesmus' habit to arnbush its prey, cat-style, rather than running it down, dog-style.
	Classification:GENUS	Name:Cynognathus	Age:Early Triassic
	Locality:Africa (South Africa) and South America (Argentina)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:The jaws of Cynognathus show without a doubt that it was a ferocious predator. It was one of the largest cynodonts, strongly built, with its hindlimbs placed directly beneath its body. Its head was more than 1 ft/30 cm long. Practically the whole of the lower jaw on each side was made up of a single bone, the dentary, into which were set the teeth - the cutting incisors, stabbing canines and shearing cheek teeth. A great bony flange (the coronoid process) at the back of the dentary articulated with the skull, and enabled the jaws to be opened wide. This flange also provided a large area to which extra jaw muscles could attach, giving the jaws tremendous bite-power.
	Classification:GENUS	Name:Dapedium	Age:Late Triassic to Early Jurassic
	Locality:Asia (India) and Europe (England)	Size:14 in/35 cm long	Fossil Name:
	Notes:The deep, round body of Dapediurn (another member of the sernionotids) was stabilized by long dorsal and anal fins at the rear. Its body was covered in heavy, protective scales with a thick outer layer of enamel. Dapedium had long, peglike teeth in its short jaws and crushing teeth on its palate. These, combined with its body shape, suggest that it was a mollusk, eater, weaving slowly through the coral reefs of the Early Mesozoic seas.
	Classification:GENUS	Name:Dartmuthia	Age:Late Silurian
	Locality: Europe (Estonia)	Size:4 in/10 cm long	Fossil Name:
	Notes:The broad head shield is the only part of Dartmuthia that is known. It was a bottom-feeder, with a round, sucking mouth on the underside of the head, like its contemporary Tremataspis (above). There was a small dorsal fin halfway along its back, and the pressuresensitive organs were well developed on its head and behind the eyes.
	Classification:GENUS	Name:Daspietosaurus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:28 ft/8.5 m long	Fossil Name:
	Notes:The short, deep jaws of this massive meat-eater held even larger teeth than other tyrannosaurs, though they were fewer in number. Each tooth was dagger-sharp, curved and saw-edged. Formidable jaws, clawed feet and sheer bulk (with a body weight of up to 4 US tons/3.6 tonnes - these were the weapons used by Daspletosaurus. It was capable of killing the large, horned dinosaurs (ceratopians) that browsed in the forests of northern North America at the time.
	Classification:GENUS	Name:Deinonychus	Age:Early Cretaceous
	Locality:North America (Montana)	Size:10-13 ft/3-4 m long	Fossil Name:
	Notes:The discovery of Deinonychus in 1964 in the claystones of Montana is one of the most exciting finds in the recent history of paleontology. Well-preserved skeletons tons reveal a dinosaur built for the chase and the kill - a fast, agile, intelligent predator. Deinonychus had the lightweight body characteristic of the coelurosaurs, from which it probably evolved. It was, on average, 10ft/3m long, stood about 6ft/1.8m tall, and weighed some 150lbs/68kg. The large head was equipped with many meat-shearing teeth, with serrated edges, which were curved backward to allow great chunks of flesh to be torn from the prey. The arms were quite long for a theropod (though still much shorter than the legs). and hung from sturdy shoulder girdles. Each hand had 3 grasping fingers with long, strongly curved claws. The legs were slender, with long shin bones and 4 clawed toes on each foot. The first toe was tiny and nonfunctional, as in most of the later them the third and fourth toes carried the whole weight of the body. But it was the remarkable adaptation of the second toe that gave Deinonychus its most offensive weapon - and its name, which means "terrible claw." The second toe on each foot had a large, sickle-shaped claw, 5 in/13 cm long. This would have been used like a dagger, to slash through a victim's flesh as Deinonychus stood on one leg and kicked with its free foot. When Deinonychus ran, the sickleclawed toes were flicked back and held clear of the ground. The body was held horizontally and balanced by the long, outstretched tail. This was kept rigid by bundles of bony rods that grew out from the vertebrae themselves, and formed a supporting framework to stiffen the tail along most of its length. When Deinonychus was standing on one foot and attacking with the other, balance was essential and a tail like a ramrod would have made the pose easier to hold. The big brain (evident from the size of the skull's brain cavity) would have coordinated a finely tuned nervous system to control such complex movements. One of the finds in Montana revealed 5 complete skeletons of Deinonychus lying by the body of a large, plant-eating dinosaur called Tenontosaurus, which measured some 24 ft/7.3 m long (see p. 141). This assemblage of bodies was most probably brought together by chance after death, washed down by a flood into a hollow or river basin.But one could perhaps reconstruct the scene that took place some 140 million years ago. A small pack of Deinonychus surrounded the plant-eater. Some may have leapt on its back and held on with their clawed hands, while slashing through its thick hide by repeated kicks of the daggerlike, killing claws on their feet. The plant-eater may have wounded or even killed some of its attackers by lashing out with its long, heavy tail or rearing up on hindlegs to crash down on their bodies. But, perhaps in the end, it succumbed and bled to death, while the pack of carnivores waited nearby. The active, predatory lifestyle sug,gested by the anatomy of Deinonychus is seen by some paleontologists as strong evidence that it was an endothermic ("warm-blooded") creature, and could control its body temperature, as do modern birds and mammals (see pp. 92-93).
	Classification:GENUS	Name:Deinosuchus	Age:Late Cretaceous
	Locality:North America (Texas)	Size:possibly 49 ft/15 m long	Fossil Name:
	Notes:Only the skull of this immense crocodile has been found. It measured more than 6ft 6in/2m in length. Assuming Deinosuchus had the same body proportions as those of other crocodiles, its overall length is judged to be just under 50 ft/ 15.2 in. The name Deinosuchus reflects this size; it means "terrible crocodile". Sometimes it is called Phobosuchus, meaning "horror crocodile." Deinosuchus lived in the swamps of Texas toward the end of the Cretaceous period. It probably ambushed passing dinosaurs, lying very still and grabbing its prey in the same way as the modern Nile crocodile seizes mammals and birds that come to the water's edge to drink. It probably swallowed stones, like its modern counterparts, which re, remained in the stomach to act as stabilizing ballast in the water. Some paleontologists, however, dispute this lifestyle. They suggest that Deinosuchus was a smaller, short, bodied, long-legged predator that lived on land. Until more of the skeleton is found, the way of life of this giant crocodile will remain uncertain. Gigantic crocodiles were not confined to the Mesozoic. Rhamphosuchus was a gavial from the Pliocene deposits of India. Only part of its jawbone is known, but it is estimated that this creature may have been the same size as Deinosuchus.
	Classification:GENUS	Name:Deinotherium	Age:Miocene to Pleistocene
	Locality:Europe (Germany and Bohemia), Asia (India) and Africa (Kenya)	Size:13 ft/4 m high	Fossil Name:
	Notes:The most remarkable feature of this elephant was its tusks, the purpose of which is still debatable. There were no tusks in the upper jaw, but the lower jaw was curved downward at a right angle and gave rise to two huge curved tusks. Such a shape seemed so unlikely that when scientists in the 1820s attempted the first reconstructions of Deinotherium, they attached the jaw upside down. The animal may have used the tusks for stripping the bark from trees or digging up tubers. Surviving almost unchanged for 20 million years, Deinotherium was clearly a very successful animal.
	Classification:GENUS	Name:Deltoptychius	Age:Early to Late Carboniferous
	Locality:Europe (Ireland and Scotland)	Size:18 in/45 cm long	Fossil Name:
	Notes:This early ratfish had practically all the features of its modern descendants. It swam by flexing the long body and whiplash tail from side to side, and gliding on its outstretched, winglike pectoral fins. Its large eyes enabled it to see better in the ocean depths, while large dental plates (rather than indiv, idual teeth) crushed shellfish.
	Classification:GENUS	Name:Dendropithecus	Age:Early to Middle Miocene
	Locality:East Africa (Kenya)	Size:2 ft/60 cm tall	Fossil Name:
	Notes:It is now widely thought that it was not Pliopithecus but its earlier relative, the' slim-built Dendropithecus ("tree ape" that was ancestral to the gibbons. Re mains of Dendropithecus have been dated to about 15 million to 20 million years ago. Although it had shorter arms and a longer tail than Pliopithecus, and was probably no better at brachiating, Dendropithecus was more gibbonlike in other respects, including its diet. Dendropithecus almost certainly inhabited a densely-forested area and enjoyed fruit, leaves and flowers, just as the gibbon does today.
	Classification:GENUS	Name:Desmatophoca	Age:Middle Miocene
	Locality: Asia (Japan) and North America (California and Oregon)	Size:5 ft 6 in/1.7 m long	Fossil Name:
	Notes:The typical streamlined shape of the modern sealion had begun to appear with Desmatophoca. As in its living relatives, its forelimbs were stronger than the hindlimbs, and the feet were modified to form paddles, with the fingers elongated, splayed out and held to, gether by webs of skin to produce a large surface area for swimming. All the bones in the limbs were shortened to make them stronger. Although Desmatophoca still had a tail, in contrast to the sealions, this was greatly reduced, being only about the length of the animal's skull. Like its ancestor Enaliarctos, its eyes were enormous, which suggests that sight was its most important sense for hunting. Its hearing may not have been fully adapted for underwater sounds, but no doubt served the animal well on land.
	Classification:GENUS	Name:Desmatosuchus	Age:Late Triassic
	Locality:North America	Size:16 ft/5 m long	Fossil Name:
	Notes:This large North American actosaur had particularly heavy armor encasing its body. Great quadrangular plates covered its back and tail and part of its belly, while long spines, up to 18 in/45 cm long, projected sideways from its shoulders. It had the small head, piglike snout and weak, peglike teeth characteristic of the plant-eating aetosaurs.
	Classification:GENUS	Name:Desmostylus	Age:Miocene
	Locality:Asia (Japan) and North America (Pacific coast)	Size:6 ft/1.8 m long	Fossil Name:
	Notes:Desmostylus was a typical member of the group. Built like a hippopotamus, and perhaps behaving like one too, it had a thickset body and stout legs with broad feet, each with 4 hooved toes. The bones of the lower foreleg were fused into a solid pillar, which meant that the foot could not be turned without turning the whole limb. Underwater, the animal probably poled itself along, in the same manner as a modern hippo "walks" over the riverbed. On land, Desmostylus must have been quite clumsy. The front parts of both the upper and lower jaws were elongated and carried an array of forward-pointing tusks, formed by the elongated incisors and canines. The animal's head must have looked similar to that of some of the shovel-tusked elephants that lived at the time. The unusual back teeth formed clusters of upright cylinders. Desmostylus must have had an amphibious lifestyle, paddling around in the coastal shallows, prising shellfish off rocks with its front tusks. It may also have sunk to the seabed in search of food. Some paleontologists suggest that it grazed on the seaweeds between the tides.
	Classification:GENUS	Name:Diacodexis	Age:Early Eocene
	Locality: Europe (France), North America (Wyoming) and Asia (Pakistan)	Size:20 in/50 cm long including tail	Fossil Name:
	Notes:The earliest-known of the artiodactyls, Diacodexis had simple teeth, and all 5 toes were present (though as in most artiodactyls, the third and fourth were the longest). There may also have been small hooves on the toes. Diacodexis must have lived in forest undergrowth, browsing leaves from bushes. Diacodexis had much the same shape and general appearance as a muntjac deer, but with short ears and a long tail. The legs, too, were relatively longer than a rabbit's, and forelimbs and hindlimbs were equal in length. This implies that Diacodexis ran rather than hopped and jumped. Indeed, it is the most highly-adapted running animal known from Eocene times - the joints restricted the feet to an up-and-down movement, and the foot and lower leg bones were longer than the upper.
	Classification:GENUS	Name:Diadectes	Age:Early Permian
	Locality:North America (Texas)	Size:10 ft/3 m long	Fossil Name:
	Notes:This creature was one of the bulkiest land animals alive in Early Permian times. Its skeleton was like that of a reptile, and well adapted to life on land. But certain features of the skull prove that it was not a member of that group. Diadectes had a specialized skull, with a secondary bony palate (a feature found in advanced reptiles, see p. 185), though this was only partially developed. It had stout grinding teeth in its short, strong jaws. It is possible that Diadectes ate shellfish, but its bulky body suggests that it ate plants. If so, it was the first amphibian herbivore, and lived at the same time as the first reptilian herbivore, Edaphosaurus (see p. 189).
	Classification:GENUS	Name:Diadlaphorus	Age: Early Miocene
	Locality:South American (Argentina)	Size:4 ft/1.2 m	Fossil Name:
	Notes:The graceful Diadiaphorus would have been very much like a short-necked antelope or pony in appearance. It was about the size of a sheep, but with the feet of a 3-toed horse. Although the paired bones of the lower limbs (ulna/radius and tibia/fibula) never fused as they did in the later true horses, the legs were long and slender. The middle toe (the third) was very large and bore the animal's entire weight, while the toes to each side (the second and fourth) had atrophied. The head was relatively short and deep, and the brain case was quite large. The low,crowned teeth, however, were quite different from a horse's and sug, gest that Diadiaphorus probably lived by browsing on the softer vegetation, bushes and trees of Patagonia's plains.
	Classification:GENUS	Name:Diatryma gigantea	Age:Early Eocene
	Locality:Europe (Belgium, England and France) and North America (New Jersey, New Mexico and Wyoming)	Size:7 ft/2.1 m tall	Fossil Name:
	Notes:Diatryma gigantea belongs to a family of giant flightless birds that lived in North America and western Europe during the Paleocene and Eocene when these continents were still joined together. Like other members of its family, Diatryma gigantea was a heavily built bird with tiny wings, incapable of flight. Its stout legs were armed with strong, clawed feet, and the large head, with its massive, hooked beak, was almost the size of that of a modern horse. Some paleontologists suggest that diatrymids were the carnivores of the day in the northern hemisphere. This is deduced from the fact that there were no other large predators around at the time. So, like the later phorusrhacids in South America (above), the diatrymids may have been the dominant predators. Other paleontologists, however, have suggested that diatrymids were herbivorous creatures that used their heavy, sharp-edged beaks to shear through vegetation, such as tussocks of grass or rushlike growth.
	Classification:GENUS	Name:Dicraeosaurus	Age:Late Jurassic
	Locality:Africa (Tanzania)	Size:41 ft/12.6 m long	Fossil Name:
	Notes:Not all diplodocids were giants. Dicraeosaurus was a relatively small member of the family. It was different in other ways, too - its neck was shorter, its head larger and its tail lacked the whiplash end. The tall spines that projected from the vertebrae, and provided muscleattachment points, were not straight as in Diplodocus and Apatosaurus. Each spine was forked at the top, like a " Y, " and this feature gives Dicraeosaurus its name - "forked lizard." These tall spines were not confined to the lower back and upper tail as they were in other diplodocids. They ranged along the whole length of the back and even up into the neck. Perhaps they carried strong ligaments, which linked several vertebrae at a time to give extra strength to the backbone. The remains of Dicraeosaurus were found in the fossil-rich rocks of Tendaguru Hill, in modern Tanzania. These Late Jurassic rocks yielded many other dinosaurs, including the giant sauropod Brachiosaurus (see p. 128) and the plated dinosaur Kentrosaurus, a relative of Stegosaurus (see p. 156). All these plant-eaters lived together peacefully on the tropical river plains of eastern Africa, browsing on different plants at different levels, and so avoiding competition with each other.
	Classification:GENUS	Name:Dicynodon	Age:Late Permian
	Locality:Africa (South Africa and Tanzania)	Size:SIZE: 4 ft/1.2 m long	Fossil Name:
	Notes:Dicynodon had the characteristic pair of canine tusks in its upper jaw, which gives the dicynodont group its name, "2 dog teeth." It may have used these strong tusks to root up plants. Another group of herbivorous reptiles, the pareiasaurs, were contemporaries of Dicynodon. Some of these were elephantine beasts, heavily armored and with a full set of leafshaped teeth in their jaws. This was quite a different dentition to that of the horny-beaked, virtually toothless dicynodonts. These 2 types of unrelated reptile avoided competition with each other by eating different plants.
	Classification:GENUS	Name:Didolodus	Age:Early Eocene
	Locality:South America (Argentina)	Size:Possibly 2 ft/60 cm long	Fossil Name:
	Notes:The teeth of this creature were so much like those of the earliest hoofed animals that in life Didolodus may have resembled one closely. A fleet-footed browser, which scampered through the undergrowth of the forests and eating the leaves of lowgrowing trees and bushes, Didolodus or something closely related to it - may have been ancestral to most of the other hoofed South American mammals.
	Classification:GENUS	Name:Dilophosaurus	Age:Early Jurassic
	Locality:North America (Arizona)	Size:20 ft/6 m long	Fossil Name:
	Notes:First discovered in 1942 by an expedition from the University of California, Dilophosaurus seems to have been a lightly built carnosaur. This sounds like a contradiction, but it was intermediate in structure between the 2 groups. Its head was large (a typical carnosaur feature) but lightboned, while its neck, tail and arms were long and slender (typical coelurosaur features, see pp. 106-113). The skull of Dilophosaurus was unusual for any group. A pair of semicircular, bony crests rose vertically on either side of the skull. Although waferthin in places, they were strengthened by vertical struts of bone. At the back of the head, the tip of each crest narrowed into a spike. The function of these head crests remains a mystery. Some paleontologists think that they could have been sexual display structures, and that only the males had them - a theory supported by the fact that not all specimens found had the crests. Indeed, there were none on the first few skeletons unearthed, and the animals were thought to have been a species of Megalosaurus (below). The crests have never been found actually attached to the skull, but lying nearby, so there is a certain amount of educated guesswork about their position in life. The jaws of Dilophosaurus give a clue to its lifestyle. The lower jaw was strong and full of long, sharp, thin teeth. The upper jaw had a cluster of teeth at the front, separate from the rest of the teeth - rather like the arrangement in the jaws of a modern crocodile. So, although Dilophosaurus had large head and strong jaws, it probably did not kill its victims by biting them; the thin teeth and delicate head crests would have been too vulnerable in a fight. More likely, this dinosaur caught and ripped its prey with the clawed feet and hands. Or, like many of its relatives, it could have fed on the corpses of creatures killed by stronger carnosaurs.
	Classification:GENUS	Name:Dimetrodon	Age:Early Permian
	Locality:North America (Oklahoma and Texas)	Size:10 ft/3 m long	Fossil Name:
	Notes:The spectacular "sail" on the back of the sphenacodont Dimetrodon has earned it the popular name of the "finback." This structure is believed to be an early experiment in controlling body temperature. The framework for the sail was provided by the elongated spines of the back vertebrae, up to 3 ft 3 in/ I in long in the center. In life, a sheet of skin covered the spines, and it was probably richly supplied with blood vessels. Dimetrodon's suggested routine would have been to stand with its sail oriented toward the sun in the early morning. Like a solar heater, the sail would have absorbed heat and warmed the blood, which then coursed through the body, raising the reptile's temperature so it could begin its daily hunt for food. To cool down, after a strenuous chase, for example, Dimetrodon simply angled its sail away from the sun and into the wind, dissipating heat. An interesting example of convergent evolution is seen between these synapsid sphenacodonts and the unrelated diapsid reptiles, the dinosaurs. Two dinosaurs , Spinosaurus (see pp. 118, 120) and Ouranosaurus (see pp. 143, 145) both living in West Africa during the Cretaceous - had also developed solarheating sails on their backs. According to calculations, a Dimetrodon weighing about 440lb/200kg would have taken about an hour and a half to raise its body temperature from 79'F to 90'F (26'C to 32'C). Without its sail, the same animal would have needed to bask in the sun for more than three and a half hours to achieve the same rise in temperature. The massive canines and well developed shearing teeth of Dimetrodon confirm that it was a formidable predator; its name means "2 kinds of teeth." Its prey would have included other pelycosaurs, which without the advantage of a sail would have re, mained slow and sluggish until the sun warmed them sufficiently to allow activity.
	Classification:GENUS	Name:Dimorphodon	Age:Early Jurassic
	Locality:Europe (England)	Size:4 ft/1.2 in wingspan	Fossil Name:
	Notes:Dimorphodon had the disproportionately large head typical of the rhamphorhynchs. It measured about 8in/20cm long, about a quarter of the total body length. But it had a remarkable puffinlike shape, deep and narrow, unlike that of its relatives. There seems to be no structural reason for this, since the teeth show that the jaws were simple, Perhaps the shape of the head represents some type of display structure for territorial or courtship behavior, like the showy heads of modern hornbills or toucans. The walking method of pterosaurs has long been debated. Based on studies of Dimorphodon's hips and legs, some paleontologists believe that they had an erect, birdlike stance, with the legs set directly under the body, so that they could run on their toes quite quickly. But finds of other types of pterosaur in 1986 indicate that perhaps Dimorph, odon was an exception. These recent finds show that the upper leg bones were splayed out sideways from the hips, which could only have resulted in a clumsy, sprawling, batlike gait. It is suggested that pterosaurs spent much of their time hanging from cliffs and branches, using their clawed fingers and toes to reach these vantage points, from which they could then launch themselves.
	Classification:GENUS	Name:Dinofelis	Age: Late Pliocene to Middle Pleistocene
	Locality:Africa (South Africa), Asia (China and India), Europe (France) and North America (Texas)	Size:4ft/1.2m long	Fossil Name:
	Notes:Dinofelis was a panther,sized cat, with flattened canines that werpconsiderably shorter than those of tNe sabertooths, scimitartooths or even the dirktooths. But they were longer than those of the biting cats (those that kill their prey with a single, well-placed bite). It is therefore a matter of debate among paleontologists as to which subfamily of the felids Dinofelis belongs. Dinofelis became extinct in Eurasia and North America during the Early Pleistocene, but survived in Africa until Mid-Pleistocene times. The Chinese species, D. abeli, is the largest-known form. The name Dinofelis means "giant cat," and the species name honours Professor Abel, an Austrian paleontologist.
	Classification:GENUS	Name:Dinohyus	Age: Early to Late Miocene
	Locality:North America (Nebraska and South Dakota)	Size:10 ft/3 in long	Fossil Name:
	Notes:The entelodonts reached their maximum size in the omnivorous Dinohyus of North America. This animal was much like Archaeotherium, but about the size of a bull. Although the bodily proportions were piglike, the face must have been quite different - for example, the nose was not flat, and the nostrils opened at the side of the muzzle rather than the front. Like Archaeotherium, Dinohyus fed close to the ground, its long muzzle making up for its short neck.
	Classification:GENUS	Name:Dinornis maximus	Age:Pleistocene to Recent
	Locality:New Zealand	Size:up to 11 ft 6 in/3.5 m tall	Fossil Name:
	Notes:Dinornis maximus was the tallest bird that ever existed - taller than the great ,elephant bird of Madagascar (above), but of a much lighter build. It was one of about a dozen types of flightless moa that survived in New Zealand until Recent times. Man came to the islands in about the 10th century, and over the next 800 years destroyed most of the forests by burning, and hunted the moas relentlessly, causing their extinction by 1800. All moas were bulky, heavy-legged, long-necked birds. In the absence of large carnivores and herbivores in their island home, these slow-moving birds had taken the place usually occupied by browsing mammals, feeding off the rich supplies of seeds and fruits.
	Classification:GENUS	Name:Diplocaulus	Age:Early to Late Permian
	Locality:North America (Texas)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:Diplocaulus had a flattened, triangularshaped head, like a boomerang. Two of the bones at the back of the skull had become greatly elongated on each side to form the points of the triangle. The body was short, and the limbs weak. Its tail, other nectrideans, which has led s paleontologists to think that this am, phibian swam by using up-and-down undulations of its flattened body. Diplocaulus may have lived on the bottom of ponds and streams. The "wings" on either side of the head may have acted like hydrofoils, allowing the animal to swim above the river bed facing into the current. Alternatively, perhaps the odd shape of the head made Diplocaulus awkward to swallow, and so acted as a deterrent to such local pre, dators as the thick-set, semi-aquatic labyrinthodont Eryops (see pp. 50, 52).
	Classification:GENUS	Name:Diplodocus	Age:Late Jurassic
	Locality:North America (Colorado, Montana, Utah and Wyoming)	Size:85 ft/26 m long	Fossil Name:
	Notes:Diplodocus was a huge animal, some specimens reaching lengths of 100ft/ 30m, although the average individual was 85 ft/26 in long. Most of its length was accounted for by the long neck (about 24ft/7.3m), and the extra-long tail (about 46ft/14m). The high, narrow body was only about 13ft/4m long, and the tiny head measured just over 2ft/60 cm in length. Despite its great size, Diplodocus weighed only 11 US tons/10 tonnes about one-eighth the weight of Brachiosaurus (seep. 128), and one-third that of Apatosaurus (=Brontosaurus, below), neither of which were as long as Diplodocus. The reason for this was in the lightweight structure of the animal's vertebrae, which were so hollowed out as to be almost cavernous. But the bony struts that remained were strong enough to support the animal's great frame. The name Diplodocus means "double beam," and refers to a pair of anvilshaped bones, or skids, that grew from the underside of each vertebra of the tail. These would have protected the delicate blood vessels and tissues on the underside of the tail as it was dragged over the rough ground. A well-preserved skeleton of Diplodoctaiavas found in Wyoming at the turn of the century by an expedition financed by the American steel millionaire, Andrew Carnegie. Several casts were made of this skeleton and distributed to 8 museums throughout the world. Unfortunately, the original Wyoming specimen was incomplete - the bones of the front feet were never found. But in order to complete the casts, the feet were modeled - inaccurately, as it turned out - on the feet of Camarasaurus, a sauropod that lived in Wyoming at the same time as Diplodocus (see p. 129). The mistake can be seen in the front feet - Diplodocus had only one clawed toe on each foot, not 3 as portrayed. The hindlegs of Diplodocus were longer than the front legs - as was usual among the sauropods (except for the brachiosaur family). The animal's body sloped down from the high hips. The vertebrae of the lower back, hips and upper tail had developed tall, vertical spines, which would have formed attachment points for strong muscles to operate the enormous neck and tail. It was probably Diplodocus' habit to rear up on its hindlegs, bending the tail around to form a "third leg" for balance. Stretching up with its long neck, the animal could browse on the uppermost cones and leaves of the coniferous trees that dotted the Jurassic landscape. just like today in parts of Africa where herds of giraffes gather, the trees of 150 million years ago would have had a "browsing line," below which level most of the leaves would have been stripped away. But instead of the modern browsing line at a height of about 20 ft/6 in, the Jurassic line would have been 49 ft/ 15 in above the ground. The only predators big enough to attack Diplodocus would have been members of the allosaur family, such as Allosaurus which weighed up to 2 US tons/2 tormes (see p. 117). Diplodocus' only weapons against such powerful carnivores were its tail and forelegs, combined with its bulk. The long, flexible tail, powered by great back muscles, could have swept clear a large area around the animal; its whiplash end could have stunned a predator. Another ploy could have been to rear up on hindlegs and bring the stout forelegs crashing down on its attacker.
	Classification:GENUS	Name:Dipnorhynchus	Age:Early to Middle Devonian
	Locality:Australia (Western Australia) and Europe (Germany)	Size:3 ft/90 cm long	Fossil Name:
	Notes:Even the earliest lungfishes were quite different to other lobe-finned fishes. For example, Dipnorhynchus' skull and braincase did not have the hinge joint that divided the skulls of coelacanths and rhipidistians into 2 parts. Its skull was a solid bony box, like that of the first land animals, the amphibians. This early lungfish had also lost its cheek teeth; these were replaced by a crushing surface of teethlike "blisters" on the palate and lower jaw. The palate was fused to the braincase (as in land animals).
	Classification:GENUS	Name:Diprotodon	Age:Pleistocene
	Locality:Australia (South Australia)	Size:10 ft/3 m long	Fossil Name:
	Notes:he grazing marsupials reached their greatest size in Diprotodon and its relatives. In appearance Diprotodon was rather like a rhinoceros-sized wombat. It probably fed on a particular species of salt-bush which it could scrape out of the ground with its paws. Remains of this bush have been found in the stom, ach cavities of several fossil specimens. The body, head and neck were massive, and the limbs strong. The feet were plantigrade, or flat-footed, and the weight was borne on the palms and the soles, as in a bear, rather than on the toes. Unlike that of other mammals, the outer ("little") toe of this animal was the longest - a peculiar feature with no apparent function. Complete Diprotodon skeletons have been found preserved in lake muds. In the dry climates in which these animals lived, salt crusts may have formed over the local lakes of the open landscape. The heavy Diprotodon would easily have fallen through and become entombed in the mud beneath.
	Classification:GENUS	Name:Dipterus	Age:Middle to Late Devonian
	Locality: Europe (Germany and Scotland)	Size:14 in/35 cm long	Fossil Name:
	Notes:The raised blisters that acted as teeth in Dipnorhynchus had been replace by a pair of large, fan-shaped toot] plates on the palate and on the lower jaws of Dipterus. This type of dentition was to remain practically unchanged over the next 380 million years. The arrangement of the fins, how, ever, has changed. The 2 dorsal fins of Dipterus, together with the tail fin and anal fin, have merged in modern species.
	Classification:GENUS	Name:Doedicurus	Age:Pleistocene
	Locality:South America (Patagonia)	Size:13 ft/4 m long	Fossil Name:
	Notes:As well as being protected by an armored suit, Doedicurus possessed a powerful defensive weapon at the end of its tail - a bony club covered in spikes and borne at the end of a stiff shaft. This remarkable structure bore a striking re, semblance to the maces carried by medieval knights, and like them, was probably used by its owner to flail out at enemies - such as the carnivorous borhyaenids.
	Classification:GENUS	Name:Dolichorhinus	Age:Late Eocene
	Locality:North America	Size:4 ft/1.2 m high at the shoulder	Fossil Name:
	Notes:In appearance Dolichorhinus resembled a small hornless rhinoceros with a particularly long head. Indeed, with its lowcrowned teeth, which were only suitable for chewing soft forest leaves, it probably lived very much like one of the modern rhinoceroses. The 4-toed front feet and 3-toed hind feet of its ancestors were retained, as they were through the whole brontothere line. The type of feet adapted for swift running, with reduced toes, as seen in the horses and antelopes, were never evolved in the brontotheres.
	Classification:GENUS	Name:Doryaspis	Age:Early Devonian
	Locality:Spitsbergen	Size:6 in/15 cm. long	Fossil Name:
	Notes:This pterapsid (also called Lyktaspis) had a much longer snout or rostrum than that of its relatives. There were bon\, spines set along its length (rather like the "saw" of a modern sawfish), and the mouth opened above, rather than below, the rostrum. This strange appendage must have had a hydrodynamic function, since the shape of Doryaspis suggests it was an active swimmer, probably feeding on plankton. An additional function of the rostrum among pteraspids could have been to stir up the bottom mud or sand, to root out crustacean prey. Doryaspis had unusually long, lateral keels growing from the back of the head shield. Their leading edges were armed with toothlike spines. These may have acted as gliding planes, and together with the rostrum and downturned tail, would have elevated the front of the body during swimming.
	Classification:GENUS	Name:Drepanaspis	Age:Early Devonian
	Locality:Europe (Germany)	Size:1 ft/30 cm long	Fossil Name:
	Notes:A number of heterostracans, such asi Drepanaspis, were well-adapted bottorndwellers, scavenging in the mud of the seabed for food. The front of the body was broad and flattened, and the eyes were set wide on either side of the upturned mouth.
	Classification:GENUS	Name:Dromaeosaurus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:6 ft/1.8 m long	Fossil Name:
	Notes:This dromaeosaur was the first of the sickle-clawed dinosaurs to be discovered, in Canada in 1914, and gave its name to the whole family. However, it, was not until Deinonychus (above) was unearthed in 1964 that the true nature and significance of Drornaeosaurus was assessed. Up until then, it was regarded I as either a large coelurosaur or a small carnosaur; the new find made it apparent that the creature belonged to a intermediate group, and shared features with both types of theropod. Dromaeosaurus is only known from its skull and some odd bones.- But fro such meager finds, paleontologists can piece together a picture of a dinosaur smaller than Deinonychus, intelligent and agile, a rapacious predator with large, killing claws on its toes, though not so large as those of Deinonychus.
	Classification:GENUS	Name:Dromiceiomimus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:11 ft 6 in/3.5 in long	Fossil Name:
	Notes:All ornithomimids had long, slender legs, with the shin bone (tibia) about 20 percent longer than the thigh bone (femur) - a sure sign of a sprinter. Dromiceiomimus had even longer shins than average, which indicates that it was a very fast runner indeed. The size of the brain cavity and eye sockets in the skull of Dromiceiomimus show that it had an exceptionally large brain (proportionally larger than that of a modern ostrich), and huge eyes (pro, portionally larger than those of any modern land animal). So, like modern nocturnal or night-hunting creatures, Dromiceiomimus most probably hunted after dark, chasing small mammals and lizards through the gathering gloom of the deciduous woods in which it lived.
	Classification:GENUS	Name:Dryopithecus	Age:Early to Late Miocene
	Locality: Europe (France and Greece), Asia (Caucasus) and Africa (Kenya)	Size:2 ft/60 cm long	Fossil Name:
	Notes:The evolutionary lines that developed into the modern apes and Homo sapiens may have begun with the widespread Dryopithecus ("tree ape") which lived about 12 million to 9 million years ago. Drypothecus evolved in East Africa, where the earliest remains have been found, and migrated to Europe and Asia (especially around the eastern end of the Mediterranean) when the continent of Africa fused with that of Eurasia. The chimpanzeelike limbs show that it would have walked mostly on all fours but could also walk on 2 legs. Its wrist was more like a monkey's than an ape's, so it probably walked on the flat of its hand, rather than on its knuckles as chimpanzees do. Its head, too, was rather chimpanzeelike, but it lacked the heavy brow-ridges. Dryopithecus was definitely a climbing, tree-living animal adapted to eating fruit, since its cheek teeth were too thinly enameled to chew tougher food such as roots or grasses. However, the environment of the time was developing into woodland mixed with open grassland, so it seems likely that Dryopithecus may also have moved about on the grasslands, probably in groups.
	Classification:GENUS	Name:Dryosaurus	Age:LateJurassic to Early Cretaceous
	Locality:North America (Colorado, Utah and Wyoming), Africa (Tanzania). Possibly Australia and Europe (England and Romania)	Size:up to 10 ft/3 m long	Fossil Name:
	Notes:Dryosaurus (also known as Dysalotosaurus) was one of the largest of the hypsilophodonts. Although it was also one of the earliest, its anatomy was advanced in several ways. For example, each long, slender leg had only 3 toes. And there were no teeth in the front part of the upper jaw; the horny beak at the front of the lower jaw met with a tough, toothless pad opposite on the upper jaw - an efficient arrangement for cropping vegetation. Like other members of this family of long-legged sprinters, Dryosaurus' shin bones were much longer than its thigh bones. The heavy leg muscles were concentrated around the short thigh bones, and the lower leg and long feet were operated by light but powerful tendons. This arrangement gave Dryosaurus extra speed, and is exactly the same pattern possessed by modern deer and gazelle. Dryosaurus was obviously a wideranging ornithopod, living as far apart as western North America and East Africa. In Jurassic times, these continents were only separated by a fledgling North Atlantic Ocean, and animals could still migrate across land by way of Europe and via the Siberia/Alaska link. This is why the dinosaurs found in the fossilrich beds of the Morrison Formation in the western USA are so similar to those found in Tendaguru Hill of Tanzania. Dryosaurus would, therefore, have shared its world with giant planteating dinosaurs such as Apatosaurus (= Brontosaurus), Diplodocus and Brachi, osaurus; small, rapacious carnivores like the coelurosaurs Coelurus and Elaphrosaurus; and large carnosaurs like Allosaurus and the horned Ceratosaurits.
	Classification:GENUS	Name:Dsungaripterus	Age:Early Cretaceous
	Locality:Asia (China)	Size:10 ft/3 m wingspan	Fossil Name:
	Notes:Dsungaripterus had a peculiar bony crest running along its snout, and long, narrow jaws that curved upward to a fine point at the tip. These forcepslike jaws could have been used to prize shellfish off rocks or out of crannies on the seashore. The flattened teeth at the back of the jaws crushed the shells.
	Classification:GENUS	Name:Dunkleosteus	Age:Late Devonian
	Locality:Africa (Morocco), Europe (Belgium and Poland) and North America (California, Ohio, Pennsylvania and Tennessee)	Size:11 ft 6 in/3.5 m long	Fossil Name:
	Notes:Some arthrodires grew to an enormous size, and may even have competed for fish prey with contemporary sharks such as Cladoselache (see p. 28). Dunkleosteus was the giant of the group, with a skull over 2 ft/65 cm long. Some of its relatives, such as Dinichthys and Titanichthys, rivalled it in size, at 7ft/2.1 m and 11 ft/3.4 in respectively. The bony trunk shield in Dunkleosteus stopped short of the pectoral fins, so freeing them for better control of steering and braking maneuvers. Sinuous movements of the smooth, scaleless body and the long, eel-like tail would have swept this great creature through the sea in search of its fish prey. The jointed neck and hinged body shields endowed Dunkleosteus with a slow, powerful bite. Having caught its victim, the great dental plates got to work, with the fanglike picks at the front of the jaws holding and piercing the prey, while the sharp-edged, cutting pavements at the back macerated it.
	Classification:GENUS	Name:Echinodon	Age:LateJurassic or Early Cretaceous
	Locality:Europe (England)	Size:2 ft/60 cm. long	Fossil Name:
	Notes:Only the jaw bones of this small fabrosaur have been found. But they are enough to tell paleontologists that Echinodon had a shorter head than Lesothosaurus, and that it also possessed unusual teeth at the front of its jaws. These were paired canine-type teeth, long and sharp, like the "eyeteeth" of modern cats and dogs. Such teeth were a feature of a group of contemporary ornithopods - the heterodontosaur
	Classification:GENUS	Name:Edaphosaurus	Age:Late Carboniferous to Early Permian
	Locality:Europe (Czechoslovakia) and North America (Texas)	Size:10 ft/3 in long	Fossil Name:
	Notes:Edaphosaurus was a member of the earliest-known herbivorous edaphosaurs. It had a great sail on its back, presumably with a similar function to that of Dimetrodon (above). The only difference between the sails of these 2 large reptiles was that the vertebral spines of Edaphosaurus had cross-pieces of bone along their length. Edaphosaurus' sail could also have been for display purposes. It may have been brightly colored, and used in courtship rituals, or even to recognize members of its own species. Certainly, this bulky pelycosaur was not an active creature, nor was it built for speed. Its body was long and barrelshaped to accommodate the large gut, its limbs were short and stocky, and it had a sprawling gait. Its teeth were those of a well-adapted plant-eater. As well as the closely packed, peglike teeth lining the jaws, there were also batteries of teeth on the palate, which formed a broad, chewing pavement, ideal for chopping up plant material.
	Classification:GENUS	Name:Edmontosaurus	Age:Late Cretaceous
	Locality:North America (Alberta and Montana)	Size:43 ft/13 m long	Fossil Name:
	Notes:Many skulls of this large, flat-headed duckbill have been found. The teeth are particularly well preserved, and show the typical hadrosaur pattern, Behind the toothless beak, banks of tightly packed teeth formed a veritable grinding pavement in both the upper and lower jaws. As those at the top were worn down and discarded, new teeth replaced them from the bottom. At any one time, there may have been over 1000 teeth in Edmontosaurus' mouth. The outer edge of each tooth was coated with hard enamel, which wore away more slowly than the dentine that made up the rest of the tooth. The result was that each tooth had a cutting ridge of hard, upstanding enamel. Packed so closely together in each jaw, the batteries of teeth presented a coarse, abrasive surface for pulverizing plant food. The jaw structure was rather like that of Iguanodon (see p. 144) in the way that the upper jaw could move over the lower jaw, so that the teeth ground against each other when the mouth was closed. This produced a shearing, grind, ing action between the tooth rows, capable of shredding the toughest of plant material. Indeed, Edmontosaurus and its relatives lived on coarse food, as the fossilized stomach contents of Anatosaurus showed.
	Classification:GENUS	Name:Efraasia	Age:Late Triassic
	Locality:Europe (Germany)	Size:8 ft/2.4 m. long	Fossil Name:
	Notes:Discovered in 1909 by E. Fraas and named after him, Efraasia was slightly larger than its prosauropod relatives' but otherwise similar in build. Like them, it had multipurpose hand I long fingers could have grasped Small Discovered in 1909 by E. Fraas and named after him, Efraasia was slightly larger than its prosauropod relatives' but otherwise similar in build. Like them, it had multipurpose hand I long fingers could have grasped Small plants and bundles of leaves, especially with the help of the mobile "thumbs." The wrist joint was also well developed, so the palm of the hand could be pressed to the ground easily, enabling the animal to walk on all-fours. Efraasia had a primitive feature' however; only 2 sacral vertebrae joined the hips to the backbone, which made for a rather weak arrangement of the hindquarters. All the other "lizard-hipped" dinosaurs had at least 3 vertebrae linking the hips to the spine.
	Classification:GENUS	Name:Elaphrosaurus	Age:Late Jurassic
	Locality:Africa (Tanzania)	Size:11 ft 6 in/3.5 in long	Fossil Name:
	Notes:Only one skeleton of Elaphrosaurus has been found, and, unfortunately, the skull was missing. Since the characteristic feature of the ornithomimids was that they had no teeth, it is impossible to say whether Elaphrosaurus belonged to this family. Loose teeth have been found in the same sediments, and these may belong to this dinosaur. The rest of Elaphrosaurus' skeleton, however, seems to be intermediate in structure between the earlier, Jurassic coelurids (above) and the later, Cretaceous ornithomimids (below). It may be that Elaphrosaurus, or some closely related animal, was the ancestor of the ostrich dinosaur group.
	Classification:GENUS	Name:Elasmosaurus	Age:Late Cretaceous
	Locality:Asia (Japan) and North America (Kansas)	Size:46 ft/14 m long	Fossil Name:
	Notes:"Snakes threaded through the bodies of turtles" - this description of the longnecked plesiosaurs was coined by Dean Conybeare, a nineteenth-century English paleontologist who did much of the initial work on these marine reptiles. Conybeare's description is more than vindicated in Elasmosaurus, which was the longest member of the elasmosaur family, and, in fact, the longest-known plesiosaur. More than half of its total length was neck - 26 ft/8 m out of a total of 46 ft/ 14 m. The length of Elasmosaurus' neck was due to a great number of vertebrae, 71 in all - many more than in the earliest plesiosaurs, which had about 28 neck vertebrae. This long structure would have enabled Elasmosaurus to curl its neck around sideways, making almost 2 full circles on either side of its body. It would have been only half as flexible in the vertical plane. However, had Elasmosaurus swung its neck around underwater while swimming, it would have met with great resistance from the water. Some paleontologists suggest, therefore, that the habit of such long-necked reptiles was to paddle along on the surface, their necks held clear of the water, When fish or other prey were spotted from this vantage point, the long neck was plunged into the sea, and the prey snapped up. The modern anhinga, or snake bird, has a long neck, and hunts in much the same way.
	Classification:GENUS	Name:Elasmotherium	Age:Pleistocene
	Locality:Europe (southern Russia) and Asia (Siberia)	Size:16 ft/5 m long	Fossil Name:
	Notes:As the forests of the Early Tertiary gave way to the grasslands of the Late Tertiary, many animal families adapted accordingly. Among the rhinoceroses, Elasmotherium shows the result well. Elasmotherium had no incisors, and would have used its lips to pluck grasses. The cheek teeth were like those of a huge horse - tall-crowned, covered in cement, and with wrinkled enamel. Such teeth are adapted to eating tough, abrasive grasses. As the teeth wore clown,;` the wrinkled enamel produced ridges that provided additional grinding surfaces. The teeth had no roots but grew continually to counteract wear. A grassland animal needs to be swift of foot to escape its predators, or so big and so well,armored that its predators are discouraged. As the largest known of the true rhinoceroses - almost as big as a modern elephant - Elasmotherium adopted the latter strategy. Elasmotherium's "horn" was a truly remarkable structure, 6 ft 6 in/2 In long. Most rhinoceroses have their horns growing from the snout. In Elasmotherium, however, it grew from the forehead. There was a large dome of bone here, which presumably provided a more secure anchor for the massive structure than any foundation at the tip of the nose.
	Classification:GENUS	Name:Elephas antiquus	Age:Middle to Late Pleistocene
	Locality:Europe	Size:12 ft/3.7 m high	Fossil Name:
	Notes:E. antiquits was a very large, long-leggeedd and straight-tusked elephant, whose bones are relatively common in European Pleistocene deposits. During the Pleistocene Ice Age, the ice sheet came and went over large areas of the Northern Hemisphere. During the glacial retreats - the interglacials the climate became much warmer. These interglacials tended to be warmer even than present-day climates, and subtropical conditions prevailed in places as far north as England. E. antiquus was one of the warmclimate animals that frequented the lush woodlands that existed in these places at that time. The tusks were long and straight, and slightly curved at the tip. As each interglacial came to an end and the ice sheets advanced southward again, E. antiquus moved away southward as well. Its place in the northern lands was taken by the elephant group that was well adapted to cold conditions the mammoths.
	Classification:GENUS	Name:Elephas falconeri	Age: Late Pleistocene
	Locality:Mediterranean islands (Cyprus, Crete, Malta, Sicily, southern Calabria and some of the smaller Greek islands)	Size:3 ft/90 cm high	Fossil Name:
	Notes:The genus Elephas includes the modern Indian elephant, E. maximus. The earli, est members of the genus arose in Africa early in the Pliocene, about 5 million years ago, and radiated into Europe and Asia. There are a number of interesting extinct dwarf elephants which may be separate species but were possibly varieties of their parent stock. E. falconeri stood less than 3 ft/1 In in height and lived on the Mediterranean islands. Its ancestors, probably the European elephant E. namadicus, migrated out of Africa in the Early Pleistocene and spread west into central Europe and east to India and China, and even reached Japan. During the lower sea-levels of the glacial periods, this elephant was able to reach Malta, Cyprus, Crete and Sardinia. With the rise of sea level as the glaciers melted in the interglacial periods, these areas became isolated as islands in the Mediterranean sea. In this isolation arose the dwarf form E. falconeri. Similar dwarf elephants arose on the Celebes Islands in Southeast Asia. On islands such as these, natural selection would favor animals that made best use of smaller quantities of food, and dwarf varieties and species would evolve. A modern equivalent is the small Shetland ponies that have developed on the northern Scottish islands. There is a possible dinosaurian example, also, in the dwarf ankylosaur Struthiosaurus. The experience of very small animals such as rodents, however, is the exact opposite: rodents on the Mediterranean islands were often larger than elsewhere. In the absence of natural predators, there was little need to maintain a small and slender structure that could swiftly take refuge in holes and crevices.
	Classification:GENUS	Name:Elginia	Age:Late Permian
	Locality:Europe (Scotland)	Size:2 ft/60 cm. long	Fossil Name:
	Notes:One of the last of the pareiasaurs, Elginia was also one of the smallest. Its head was decorated with the head spikes typical of the family, but they were developed into an incredible array on Elginia's small skull. Their purpose was probably more for display than for defense - perhaps this little reptile shook its head about to threaten a rival male or to attract a female.
	Classification:GENUS	Name:Elorneryx	Age:Late Eocene to Late Oligocene
	Locality: Europe (France) and North America (Dakota)	Size:5 ft/1.5 in long	Fossil Name:
	Notes:The hippopotamuslike Elomeryx had a long body and short stumpy legs, with a head which was long and superficially like that of a horse. Its teeth, however, were quite different, with elongated canines to hook up the roots of water plants, and spoon-shaped incisors for digging in the mud. Unlike other even-toed ungulates, in which the toes are usually reduced to 2, there were 5 toes (the first a "dew-claw") on the forefoot and 4 on the hind. Such broad feet would have been useful for walking on soft mud.
	Classification:GENUS	Name:Embolotherium	Age:Early Oligocen
	Locality:Asia (Mongolia)	Size:8 ft/2.5 m high at the shoulder	Fossil Name:
	Notes:The head of Embolotherium is typical of the grotesque shapes developed by the later brontotheres. From the back of the skull it swept forward in a deep hollow and then up to a massive single "horn" on the nose. The eyes were situated well forward, just behind the nostrils and at the horn's base. The shallow skull left little room for much of a brain - as in other large brontotheres, the brain was no bigger than a man's fist. The occurrence of Embolotherium in the Gobi desert of Asia gives an indication of just how widespread and successful were the brontotheres in their heyday.
	Classification:GENUS	Name:Emeus crassus	Age:Pleistocene to Recent
	Locality:New Zealand	Size:5 ft/1.5 m tall	Fossil Name:
	Notes:This moa, only half the height of Dinornis, was peculiar in having massive lower legs, which were out of all proportion to its body size. Its feet were also enormously broad. It must have been a painfully slow-moving animal, providing easy prey for the moa-hunters. The modern kiwi, the emblem of New Zealand, is regarded by some paleontologists as a highly specialized moa. The 3 living species are tiny in comparison to their extinct relatives. being less than 2 ft/60 cm tall.
	Classification:GENUS	Name:Enaliarctos	Age:Early Miocene
	Locality:North America (Pacific coast)	Size: 5 ft/1.5 m long	Fossil Name:
	Notes:This primitive-looking sea mammal represents an early stage in the adaptation of a land-dwelling carnivore to a marine lifestyle. Enaliarctos is almost half-way between an otter and a sealion. Its cheek teeth still bore meat-shearing (carnassial) blades like those of a land-living dog. Its body was streamlined and rather otterlike, with distinct legs and a tail, although the feet were already modified into paddles. Enaliarctos probably lived rather like the modern sea otter, spending time on land as well as in the water, and eating a variety of marine animals, including both fish and shellfish. However, some sealion characteristics had already evolved, such as the large eyes, sophisticated senses associated with the whiskers, and the specialization of the inner ears for detecting the direction of sound underwater. All these senses helped Enaliarctos to locate its prey. Smell probably played a minor role in hunting, as in living pinnipeds.
	Classification:GENUS	Name:Enchodus	Age: Late Cretaceous to Paleocene
	Locality:Worldwide	Size:7 in/18 cm long	Fossil Name:
	Notes:At the very end of the Cretaceous and during the Early Tertiary, a second burst of evolution led to the advanced bony fishes. Salmon and trout are survivors of this evolutionary phase, and from their ancestors descended all the mod, ern types of teleost. Enchodus was one of these early, salmonlike teleosts. Its large head and big eyes, together with the lightweight, streamlined body, suggests an agile predator of the open seas. The scales were reduced to a band along each flank; the pelvic fins were set well back on the belly, directly beneath the large, stabilizing dorsal fin; and the pectoral fins were mounted higher on the flanks, giving greater control of steering and braking. The remarkable feature of Enchodus, however, was its mouthful of greatly elongated teeth, which were slightly recurved and interlocked when the jaws were closed to form an effective trap. Enchodus probably preyed on planktoneating fishes in the surface waters.
	Classification:GENUS	Name:Eobothus	Age:Middle Eocene
	Locality:Asia (China) and Europe (England and France)	Size:4 in/10 cm long	Fossil Name:
	Notes:As evolutionary "late-comers," the flatfishes, such as Eobothus, filled one of the few remaining niches left among the spiny-rayed fish group. They became specialized for living and feeding on the seabed. Unlike the rays and skates, which became flattened from top to bottom, the flatfish became compressed from side to side. The most obvious indication of this lateral compression is the presence of both eyes on one side of the head, since the eye on the underside had to migrate onto the top side. As in all flatfish, Eobothus' dorsal and anal fins formed an almost,continuous fringe around its oval-shaped body. By undulating these fins, the fish glided over the seabed. Modern plaice, sole, turbot, halibut, and flounder are the living relatives of Eobothus.
	Classification:GENUS	Name:Eocardia	Age:Miocene
	Locality:South America	Size:1 ft/30 cm long	Fossil Name:
	Notes:Cavioids are the most typical South American rodents and are closely related to the guinea pigs and the capybara. Some became quite large. Protohydro, choerus, for example, was about the size of a tapir, but Eocardia was more modest in size, and resembled the present day guinea pig in appearance.
	Classification:GENUS	Name:Eogyrinus	Age:Late Carboniferous
	Locality:Europe (England)	Size:15 ft/4.6 m long	Fossil Name:
	Notes:Eogyrinus was a long-bodied aquatic predator, probably living an alligator-type life in the deltas and swamps of the Carboniferous coal forests. It swam after its fish prey using powerful strokes of the long tail, its body stabilized by the tall, fishlike dorsal fin on its back.
	Classification:GENUS	Name:Eomanis	Age:Middle Eocene
	Locality: Europe (Germany)	Size:20 in/50 cm long	Fossil Name:
	Notes:The earliest known pangolin, Eomanis is represented by a well-preserved fossil from the same oil shale deposits that yielded the skeleton of Eurotamandua. Even the scales were preserved, and it is quite obvious that Eomanis looked very much like the pangolins of today. The animal may have been able to close its eyes, ears and nostrils as a protection against ant stings, as the modern species can do. From the remains of Eomanis' stomach, it is clear that its diet consisted of both plant matter and insects.
	Classification:GENUS	Name:Eotitanops	Age:Early to Middle Eocene
	Locality:North America and Asia	Size:1 ft 6 in/45 cm high at the shoulder	Fossil Name:
	Notes:If you could travel back through time to watch a group of Eotitanops scampering through the undergrowth of an Early Eocene forest, it would be impossible to tell at a glance whether you were looking at Eotitanops or its distant cousin Hyracotherium. Both were small browsing mammals, with 4 toes on the front feet and 3 on the hind. But whereas Hyracotherium gave rise to the elegant and intelligent plains-dwelling horses of recent times, Eotitanops evolved into the huge, lumbering, small,brained brontotheres that failed to see out the Oligocene. It lived in North America in early Eocene times but survived into the middle Eocene in Asia.
	Classification:GENUS	Name:Epigaulas	Age:Miocene
	Locality: North America (Great Basin)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Epigaulus must have resembled a modern marmot, except for a pair of stout horns on the skull and long, powerful claws on the front feet. These claws are compressed from side to side - an adaptation to the digging habit. No other known rodent had horns like these. Since it is so evidently a burrowing animal, the function of the horns is a mystery, but they may have been used for sexual display. Epigaulus and its closest relatives died out when forests disappeared and were replaced by grassland in the Late Miocene, about 5 million years ago.
	Classification:GENUS	Name:Ericiolacerta	Age:Early Triassic
	Locality:Africa (South Africa)	Size:8 in/20 cm long	Fossil Name:
	Notes:The abundant plant life - horsetails, ferns, conifers and early cycads - that supported the great populations of dicynodonts above) also provided home and food for many insects and other invertebrates. These, in turn, were suitable prey for small therocephalians such as Ericiolacerta. This lizardlike creature was an active insectivore, judging from its small teeth and long, slim limbs.
	Classification:GENUS	Name:Eryops	Age:Late Carboniferous to Early Permian
	Locality:North America (New Mexico, Oklahoma and Texas)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:This large, semi-aquatic creature was a member of the successful eryopid family, whose members thrived from Late Carboniferous (Pennsylvanian) times to the end of the Permian. Its thick-set body and large head was supported by sturdy limbs. Bony plates covered its back, perhaps to brace the muscles and help support the heavy body on land. Eryops probably fed in water, since the position of the jaw hinge indicates that the mouth could not have been opened on land without lifting the heavy head clear of the ground.
	Classification:GENUS	Name:Erythrosuchus	Age:Early Triassic
	Locality:Africa (South Africa)	Size:15 ft/4.5 m long	Fossil Name:
	Notes:Erythrosuchus and other members of its family were the largest, land-living predators worldwide during the Early and Mid-Triassic period. Some of them reached a length of 16 ft/5 In. Their predation must have exerted a profound, selective pressure on the evolution of other terrestrial reptiles. For example, several new types of thecodontian with protective body armor appeared at around this time, such as the phytosaurs and aetosaurs (below). Erythrosuchus had a large head, up to 3 ft 3 in/ I In long, and powerful jaws filled with sharp, conical teeth. Its legs were held rather more directly beneath its bulky body than those of the sprawling Chasmatosaurus (above), suggesting that this active predator could move more effectively on land.
	Classification:GENUS	Name:Eucladoceros	Age:Pliocene to Pleistocene
	Locality:Europe (Italy)	Size:8 ft/2.5 m long	Fossil Name:
	Notes:Some of the deer evolved huge, flamboyant antlers. One of the most spectacular examples was Eucladoceros, whose antlers, each with a dozen points, or tines, had a total span of 5 ft
	Classification:GENUS	Name:Eudimorphodon	Age:Late Triassic
	Locality:Europe (Italy)	Size:2 ft 5 in/75 cm wingspan	Fossil Name:
	Notes:Eudimorphodon is well known from remains preserved in marine rocks of northern Italy. It was a typical rhamphorhynch, with a short neck and a bony tail, which made up about half the animal's length of 2ft 4in/70cm. The head was large but lightweight, owing to the 2 pairs of openings in its diapsid skull (see p. 61). The membranous flaps of skin that made up Eudimorphodon's wings were attached to the enormously elongated fourth finger of each hand. This finger was composed of 4 extra-long finger bones (phalanges), and was attached to the wrist by an elongated hand bone (metacarpal). The wings joined the body on each side at the thighs. Another small flying membrane ran from the bones of each wrist to the base of the neck. Eudimorphodon was evidently an active flyer, capable of flapping its wings like a modern bird. The sternum, or breastbone, was developed into a broad, flattened plate, to which the powerful flight muscles attached, although the keel was low in comparison to the great keel of modern flying birds. The long tail would have been held out rigidly during flight, its vertebrae lashed together by bony tendons into an inflexible rod, which counterbalanced the animal's comparatively heavy fore, quarters. As in many other rhamphorhynchs, there was a vertical, diamondshaped flap at the tip of the tail, which most probably functioned as a rudder during flight. The short jaws of Eudimorphodon were armed with 2 kinds of teeth. There were long, peglike teeth at the front of the mouth, and short, broad teeth at the back. This pterosaur probably flew low over the sea, its large eyes trained on the surface to spot its fish prey.
	Classification:GENUS	Name:Euhelopus	Age:LateJurassic or Early Cretaceous
	Locality:Asia (China)	Size:49 ft/15 m long	Fossil Name:
	Notes:Although Euhelopus and Camarasaurus lived on opposite sides of the world, the two sauropods were closely related and of similar build. There were some differences, however. For example, Euhelopus had a much longer neck, made up of 17-19 elongated vertebrae (Camarasaurus had a short neck, with only about 12 vertebrae). Nor did Euhelopus have the "pug nose" of its relative; its head was longer, with a more pointed snout. But like Camarasaurus, it had the same heavy, spoon-shaped teeth, and large nasal openings on top of its head.
	Classification:GENUS	Name:Euoplocephalus	Age:Late Cretaceous
	Locality:North America (Alberta)	Size:18 ft/5.5 m long	Fossil Name:
	Notes:Most of what paleontologists know about ankylosaurs is based on studies of this animal, carried out in the 1970s and '80s. The bands of armor were embedded in the skin of the back, and dotted with huge bony studs. There were heavy plates over the neck, and large, triangular spines jutted up to protect the shoulders and base of the tail. Externally, the head was a heavy box of bone, covered in plates that were fused to the skull bones. Inside was the complicated series of chambers and air passages that characterized both the ankylosaurs and nodosaurs. A pair of thick spines protected the sides of the face. Even the eyelids were armored, forming shutters that could descend to guard the eyes when danger threatened. These bony eyelids were only accessory structures; the real eyelids would have consisted of the usual delicate membranes. There was a horny, toothless beak at the front of the broad face. It may be that Euoplocephatus was an indiscriminate plant-eater, cropping any and all vegetation that presented itself. In contrast, its nodosaur relatives had narrow snouts, and probably were more selective feeders.
	Classification:GENUS	Name:Euparkeria	Age:Early Triassic
	Locality:Africa (South Africa)	Size:up to 2 ft/60 cm long	Fossil Name:
	Notes:The powerful hindlegs and long tail that had evolved in the ancestral thecodontians gave rise to a new stance in their descendants, the ornithosuchians. Euparkeria was an early member of this group. It was a small, slimly built creature, with a tight armor of bony plates running down the center of its back and tail. The hindlegs were longer than the forelegs, by about one-third. Although it spent most of its time on allfours, this thecodontian was capable of rising up on 2 legs to run away from danger. Its long tail, making up about half the body length, would have been stretched out behind to balance it at the hips as it ran. This 2-legged (bipedal) stance was to become the norm among the carnivorous dinosaurs that made their first appearance at the end of the Triassic (see pp. 106-109). Euparkeria's skull was large, but its weight was reduced by several wide openings between the bones. Its teeth were well suited to a carnivorous diet long and sharp, curved slightly backward and serrated along the edges.
	Classification:GENUS	Name:Eurhinodelphis	Age:Middle to Late Miocene
	Locality:Asia and North America (Pacific coasts)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:The oclontocetes diverged into a number of groups during the Oligocene, about 30 million years ago, Eurhinodelphis was a typical member of the rhabdosteid family of long-snouted porpoises. The structure of its ears had become much more complex than in earlier odontocetes, so it is likely that this whale had developed the complex echolocation system seen in modern toothed whales. Living whales use a form of ultrasonic sonar; they emit high-frequency clicking sounds which bounce off objects, and the echoes are analyzed by their large brains to determine - with astonishing accuracy - the size, shape, distance and speed of the object and, of course, its edibility. Like that of a modern dolphin, the skull of Eurhinodelphis had become somewhat assymmetrical, with structures on one side different from those on the other. This arrangement might have been associated with the development of new abilities, such as chasing fast-moving prey and navigating with increasing accuracy. The most distinctive feature of Eurhinodelphis, however, was its elongated snout. It was toothless at the tip, and may have been used like the "sword" of the modern swordfish, to strike at and stun its prey, which was then seized in the animal's jaws.
	Classification:GENUS	Name:Eurhinosaurus	Age:Early Jurassic
	Locality:Europe (Germany)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:This was an extraordinary-looking ichthyosaur, unlike any other known mem- ber of the group. Its upper jaw was twice the length of its lower jaw, giving it the appearance of a modern sawfish. Teeth stuck out sideways along the length of this bladelike projection. The function of this strange structure is not known for certain, just as the purpose of the saw of the modern saw, fish also remains somewhat mysterious. Eurhinosaurus could have used it to probe around in the sand or mud of the seabed, or among seaweeds and rocks, to flush out flatfish, shrimps or octopus. Perhaps it was also swung rapidly from side to side as Eurhinosaurus swam through a shoal of fish, stunning and wounding them as it passed.
	Classification:GENUS	Name:Eurotamandua	Age:Middle Eocene
	Locality:Europe (Germany)	Size:3 ft/90 cm long	Fossil Name:
	Notes:Until recently, when a fossil anteater was discovered in deposits of oil shale near Frankfurt in Germany, and named Eurotamandua, paleontologists thought that anteaters were confined to South America. With its long tubular snout, weak toothless jaws and powerful forelimbs- armed with huge claws, this was undoubtedly an anteater, and seems to have been very similar to the modern collared anteater Tamandua. The fossil record of anteaters is poor, so it is not known how this exciting European find fits into the overall evolutionary history of the group. Evidence of Eurotamandua's typical anteater diet is provided by the fossilized ants found at the German site.
	Classification:GENUS	Name:Eusthenopteron	Age:Late Devonian
	Locality: Europe (Scotland and USSR) and North America (Canada)	Size:up to 4 ft/1.2 in long	Fossil Name:
	Notes:This large osteolepiform rhipidistian fish is considered by most paleontologists to be the direct ancestor of the amphibians. The pyramidal arrangement of the bones in its paired fins is strikingly similar to the arrangement of the limb bones in land animals. In addition, the structure of its backbone, the pattern of the skull bones and the complex, labyrinthine folding of the enamel inside each tooth all bear a remarkable resemblance to these features in the first amphibians. Eusthenopteron was a long-bodied, predatory fish with a powerful 3pronged tail, consisting of 2 equal,sized lobes on either side of the bony axis of the vertebral column. Its pectoral fins were well forward on the body, and articulated with the shoulder girdle, which in turn articulated with the back of the skull. The pelvic fins were well to the rear, as were the 2 dorsal and anal fins.
	Classification:GENUS	Name:Eustreptospondylus	Age:Middle Jurassic to Late Cretaceous
	Locality:Europe (England)	Size:23 ft/7 m long	Fossil Name:
	Notes:A nearly complete skeleton of this early megalosaur was unearthed in southern England, and described in 1964. It is now mounted in the University Museum of Oxford, and although parts of its skull are missing, it remains the best-preserved specimen of any European carnosaur discovered to date. In build, Eustreptospondylus was so similar to Megalosaurus that, until 1964, it was still thought to be that dinosaur.
	Classification:GENUS	Name:Galechirus	Age:Late Permian
	Locality:Africa (South Africa)	Size:1 ft/30 cm. long	Fossil Name:
	Notes:This tiny lizardlike reptile is thought to be an early member of the dicynodonts - the most abundant and successful group of the plant-eating therapsids (see pp. 190-193). But Qalechirus'teeth seem to be those of an insectivore. Many paleontologists think that Qalechirus simply represents the juvenile form of an adult therapsid.
	Classification:GENUS	Name:Gallimimus	Age:Late Cretaceous
	Locality:Asia (Mongolia)	Size:13 ft/4 in long	Fossil Name:
	Notes:This is the largest ostrich dinosaur to be discovered to date. It differs from its close relatives, Ornithomimus and Struthiomimus, in 2 respects. It had a long snout ending in a broad, flat-tipped beak, and its hands seem poorly designed for grasping. Perhaps it was a specialist feeder; it could have dug out other dinosaurs' eggs buried in the soil with its spadelike hands, and cracked them open with its heavy beak. An exciting discovery in 1965, from Late Cretaceous deposits in the Gobi Desert of Mongolia, has led paleontologists to believe that there were much larger birdlike dinosaurs around at the same time as Qallimimus (above). The fossil find consisted of a pair of shoulder bones and arms belonging to what must have been a gigantic creature. Each arm measured 8 ft/2.5 m in length, from the shoulder down to the tip of the 3 powerful, clawed fingers. Each claw bone alone was about 10 in/ 2 5 cm long, and would have carried an even longer nail. No other parts of the skeleton have been found, so it is impossible to say whether this animal was an ornithornimid. It was certainly a very large theropod dinosaur. Predictably, it has been given the descriptive name of Deinocheirus, meaning "terrible hand," and is placed in a family of its own.
	Classification:GENUS	Name:Gemuendina	Age:Early Devonian
	Locality:Europe (Germany)	Size:1 ft/30 cm long	Fossil Name:
	Notes:The rounded, flattened body of this early bottom-dwelling placoderm (of the rhenanid order) was remarkably like that of a modern ray. Its pectoral fins were drawn out into winglike lobes on 1 either side of the body, and the eyes and nostrils were repositioned on top of the head. These features were duplicated about 260 million years later in an unrelated group of fishes - the rays and skates that dwelt on the seabed from Jurassic times onward (see p. 29). Here is an excellent example of convergent evol, ution - in which unrelated creatures adopt the same structure, and often the same habits, in response to a similar environment and lifestyle (see p. 16). Qemuendina did not have the heavy armor of its later relatives. A mosaic of small bony plates covered its body, decorated with sharp, defensive dent, icles; a few large plates were developed above and below the head. This placo,1 derm - also lacked the characteristic tooth plates of its later relatives. Instead, the jaws were equipped with star shaped tubercles, which acted like teeth; the jaws could be protruded out of the mouth to pick up sea urchins and shellfish from the seabed, which were then crushed between the teethlike tubercles.
	Classification:GENUS	Name:Gerrothorax	Age:Late Triassic
	Locality:Europe (Sweden)	Size:3 ft 3 in/1 m. long	Fossil Name:
	Notes:The general trend toward flattening the body reached its climax among the plagiosaurs, such as Qerrothorax. This large amphibian probably lay quite still on the stream or take bed, camouflaged among the sand and pebbles, and watching for fish with its upwardly directed eyes. It may even have attracted prey with a fleshy, brightly colored lure dangling inside its open mouth. Once the prey was within easy reach, Qerrothorax would have swiftly closed its gaping jaws, trapping the victim. Qerrothorax could live permanently in water because it still retained the 3 pairs of feathery gills that it possessed as a larva. So, this ancient creature clearly proves that fossil amphibians, like their modern counterparts, went through an aquatic, gill-breathing, larval stage before developing into a 4-legged, lungbreathing adult. ORDER ANTHRACOSAURIA The anthracosaurs; (also known as batrachosaurs) were labyrinthodonts that arose during the Carboniferous and survived until the middle of the Permian. They were not so numerous or diverse as the temnospondyls (above), but among their members were the ances- tots of the reptiles.
	Classification:GENUS	Name:Gigantopithecus	Age:Late Miocene to Middle
	Locality:Asia (China, Pakistan, India)	Size: 10 ft/3 rn tall	Fossil Name:
	Notes:This enormous creature, a veritable King Kong of the fossil apes, must have weighed something like 650lb/300kg. A close relative of Sivapithecus, it is known mostly from remains of jaw fragments and teeth, which were about twice the breadth of the teeth of a modern gorilla. They first came to the attention of scientists when a paleontologist saw 4 single molars in a Hong Kong drugstore in the 1930s. Some complete lower jaws were discovered in the 1950s. Qigantopithecus was a ground, dwelling ape, something like a gorilla in appearance, but with a shorter jaw and relatively small incisors and canines. It probably ate roots, tubers and seeds, but also small vertebrates. Qigantopithecus certainly lived until Pleistocene times, about I million years ago, and perhaps until more recently. Indeed, it has been surmised that Qigan, topithecus is not extinct even now, but still survives in the foothills and passes of the Himalayas, where it is occasionally sighted and identified as the Yeti.
	Classification:GENUS	Name:Glossotherium	Age:Pliocene to Pleistocene
	Locality:North America (California)	Size:13 ft/4 m. long	Fossil Name:
	Notes:The Rancho La Brea tar pits in Los Angeles have yielded excellent specimens of this great ground sloth, which traveled up from South America, some 3 million years ago, over the newly reformed land bridge, There it met its fate in the sticky pools of crude oil that had seeped up to the surface and lay innocently covered by water. Qlossotherium was a bulky creature, with a large head and heavy tail. Its long, clawed feet were turned inward, as they are in its relatives, so it walked on its knuckles, gorilla-style. Qlossotherium could rear up on its hindlegs, and used the long claws to bring food to its mouth. It seems to have lived on desert shrubs, to judge by the plant remains preserved in its fossil droppings.
	Classification:GENUS	Name:Gomphotherium	Age:Early Miocene to Early
	Locality: Europe (France), Africa (Kenya), Asia (Pakistan) and North America (Nebraska)	Size:10 ft/3 m high	Fossil Name:
	Notes:This 4-tusked mastodont was wideranging, cropping up as fossils on 4 continents. As a result, the same fossil animal has been given a variety of names, including Trilophodon and Tetrabelodon. The lower jaw, with its parallel tusks, was very long. It was probably used in conjunction with an equally long trunk on the upper jaw. There was a progressive reduction in the number of teeth, but those that remained developed a number of high ridges or cusps to increase the grinding area. This was necessary to cope with the large amounts of plant food required to satisfy the animal's immense bulk. Most members of the genus Qomphotherium ate the leaves from bushes, but one species was a swamp dweller and ate soft water-plants.
	Classification:GENUS	Name:Gracilisuchus	Age:Middle Triassic
	Locality:South America (Argentina)	Size:1 ft/30 cm long	Fossil Name:
	Notes:This tiny creature is so unlike a modern crocodile that it was classified with the ornithosuchians until the early 1980s. Like them, it had a lightly built body and a disproportionally large head, and it could run erect on its slim hindlegs, balanced by the long, straight tail. However, the structure of Qracilisuchus' skull, neck vertebrae and ankle joints place it firmly among the crocodiles. Qracilisuchus was a well-adapted land animal, protected by a double -row of bony plates that interlocked down the length of its backbone, to the tip of the tail. It probably chased after small lizards on its long hindlegs, despatching them in its powerful jaws, with their sharp, recurved teeth.
	Classification:GENUS	Name:Griphognathus	Age: Late Devonian
	Locality:Australia (Western Australia) and Europe (Germany)	Size:2 ft/60 cm long	Fossil Name:
	Notes:By the end of the Devonian, various specialized types of lungfish had evolved. Qriphognathus had an elongated snout, and small, teethlike denticles, capped with enamel, studded its palate and lower jaws. Like all its relatives, this lungfish was covered in large, overlapping, rounded scales, and the tail was asymmetrical.
	Classification:GENUS	Name:Groenlandaspis	Age:Late Devonian
	Locality:Antarctica (South Victoria Land), Australia (New South Wales), Europe (England, Ireland and Turkey) and Greenland	Size:3 in/7.5 cm long	Fossil Name:
	Notes:This tiny armored fish, found in sites literally poles apart, was a member of the most abundant and diverse group of placoderms - the arthodires, or "jointed-necked" fishes. They account for 60 percent of all known placoderms. Qroenlandaspis was a flattened bottom-dweller, crushing mollusks and crustaceans between its tooth plates. Since the lower jaw could not be dropped while the fish was lying flat on the seabed, this fish, like most of its relatives, evolved an ingenious hinge system to allow them to open their jaws wide to engulf large prey. The head shield was hinged to the trunk shield by a pair of ball-and-socket joints set high up on either side of the body. These hinges allowed the head to be tilted up and back, while the lower jaw dropped and the gaping mouth moved forward to seize the prey.
	Classification:GENUS	Name:Gyroptychius	Age:Middle Devonian
	Locality:Europe (Scotland)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Qyroptychius was a fast-moving, longbodied predator in Devonian rivers, with small eyes and a keen sense of smell. Like other porolepiforms, it had short jaws. This actually enhanced the bite-power of the jaws. Qyroptychius had fleshy, muscular fins, all of which, except for the pectorals, were concentrated at the rear of the body. This increased the propulsive force of the arrow-shaped tail.
	Classification:GENUS	Name:Hadrosaurus	Age:Late Cretaceous
	Locality:North America (Montana, New Jersey, New Mexico and South Dakota)	Size:30 ft/9 m long	Fossil Name:
	Notes:Hadrosaurus, meaning "big lizard," has the distinction of being the first dinosaur to be discovered in North America. Its bones were found in New Jersey, and it was reconstructed and named in 1858 by the American professor of anatomy, Joseph Leidy, of the University of Pennsylvania. He recognized that Hadrosaurus was structurally related to Iguanodon, whose remains had first been found in southern England, and described in 1825. But unlike the early, inaccurate reconstructions of Iguanodon by Mantell, the geologist - as a 4-legged, dragonlik, creature - Leidy, the anatomist, knew from the structure of Hadrosaurus that it could also rise up on its hindlegs. He showed it in a running pose as a bipedal animal - standing upright on 2 legs, its short arms dangling and its body bent horizontal to the ground, balanced by the long, outstretched tail. Hadrosaurus was the typical member of the duckbill family. Like Kritosaurus (above), it had no crest on its long' low head, but there was a large hump on its snout, made of solid bone, and probably covered with thick, hard skin. Its bill, at the front of the jaws, had no teeth, but there were hundreds of teeth at the back of the jaws, in a continual state of replacement. Hadrosaurs could move their upper and lower jaws against each other vertically and horizontally. This produced strong chewing and grinding actions, which would have thoroughly pulverized the food before it was swallowed.
	Classification:GENUS	Name:Hapalops	Age: Early to Middle Miocene
	Locality:South America (Patagonia)	Size: 30 cm/1 m long	Fossil Name:
	Notes:By Miocene times, some 20 million years'ago, ground sloths were well established in South America. Hapalops was an early Miocene member of the group, and small in comparison with its later relatives. Its short head, stout body and long tail were supported on long, slender forelegs and even longer, heavier hindlegs. The long, curved claws on all its toes must have forced this sloth to walk on the knuckles of its front feet, rather like a modern gorilla. But being of fairly light build, Hapalops could have spent some of its time in trees, clinging on with its sharp,clawed feet and using its long legs to hook down succulent leaves and fruit. Like all the edentates, Hapalops had very few teeth, only 4 or 5 pairs of cheek teeth remaining in its jaws.
	Classification:GENUS	Name:Haramiya	Age:Late Triassic to Early Jurassic
	Locality: Europe (England and Germany)	Size:5 in/12 cm long	Fossil Name:
	Notes:Haramiya is known from only a few isolated teeth. This fragmentary evidence suggests that it was somewhat like a miniature vole, and crushed its food with its broad cheek teeth. It may have lived on low-growing vegetation, possibly on the fruits of cycad-like plants.
	Classification:GENUS	Name:Harpagornis moorei	Age:Pleistocene to Recent
	Locality:New Zealand	Size:possibly 3 ft 6 in/1. I m tall	Fossil Name:
	Notes:This eagle may not have been much larger than many of its modern relatives, the eagles and Old World vultures, but it was stronger and more heavily built. The legs were stout and equipped with heavy talons, the beak was deep and sharply hooked, and the powerful wings spanned some 7 ft/2.1 In. Harpagornis moorei coexisted with the moas in New Zealand, and became extinct at about the same time - perhaps as recently as the 17th 'century, Since there were no other large predators on the islands, it may have fed on the smaller moas, such as Emeus crassus (above), and on other birds, such as the now-extinct flightless goose. Moas would have been bulky prey to attack, but their probable slowness, together with their relatively small heads and long necks, could have made them vulnerable to aerial attack. Certainly, their chicks would have provided easy prey for these powerful raptors.
	Classification:GENUS	Name:Hayoceros	Age:Middle Pleistocene
	Locality:Nebraska	Size:6 ft/1.8 m long	Fossil Name:
	Notes:Hayoceros had 4 horns: 1 pair of broad, forked horns over its eyes, as in the pronghorn, and another much longer, narrower pair farther back at the top of its skull. When 2 males competed for mating partners, they probably adopted a sparring technique similar to that of living pronghorns, which lock their forked horns and push until the weaker of the pair retires. These ritualistic bouts rarely seem to result in any permanent injury.
	Classification:GENUS	Name:Heinicyon	Age: Early to Late Miocene
	Locality:Asia (Mongolia), Europe (France and Spain) and North America (USA)	Size: 5 ft/1.5 m long	Fossil Name:
	Notes:Despite its great size, Hemicyon was lightly built for a bear. Indeed, it was more like a heavy dog, and its name means "half-dog." It was probably more carnivorous than most other bears, and so was likely to have been an active hunter. It had powerful legs, and the structure of its feet indicate that it ran on its toes - an adaptation for fast running - rather than with the whole foot pressed to the ground as in modern bears. These features suggest that Hemicyon was a hunter of the open plains, possibly roaming about in packs.
	Classification:GENUS	Name:Hemicyclaspis	Age: Early Devonian
	Locality: Europe (England)	Size:5 in/13 cm long	Fossil Name:
	Notes:This osteostracan was a more powerful swimmer, and could maneuver itself better in the water, than either of its bottom-dwelling relatives Tremataspis or Dartmuthia (above). A dorsal fin stabilized the body, while a pair of scalecovered flaps, like pectoral fins, provided uplift and kept it on course. The corners of the head shield were drawn out into keel-like cutwaters. And the enlarged upper lobe of the tail produced lift at the rear of the body, so keeping the fish's head down while it sucked up food from the seabed.
	Classification:GENUS	Name:Henodus	Age:Late Triassic
	Locality:Europe (Germany)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:The body of Henodus was as broad as it was long - the same shape as that of a modern turtle. Its back and belly were covered in an irregular mosaic of many, sided, bony plates. These formed a de, fensive shell to protect it from attack by other marine reptiles in the Triassic seas, such as the ichthyosaurs. Many more plates made up the shell of Henodus than are present in the shell of a modern turtle. But as in a modern turtle, the shell was completely covered by plates of horn. Henodus' head was peculiarly square and boxlike. There were no teeth in its jaws; instead, there was probably a horny beak, like that of a modern turtle, which could be used effectively to both dislodge and crush shells.
	Classification:GENUS	Name:Heptodon	Age:Early Eocene
	Locality:North America (Wyoming)	Size:3 ft 4 in/I m long	Fossil Name:
	Notes:Heptodon, an early helaletid, had already evolved the characteristic tapir-shaped body_.but had no trunk. The short trunk that,"is such a distinctive feature of modern tapirs was just beginning to evolve as a fleshy outgrowth of the upper lip in Helaletes, a relative of Hep, todon that lived during the Middle and Late Eocene in North America and Asia. The trunk is a valuable adaptation, which tapirs used as a sensitive tool for pulling within reach and handling the twigs and leaves on which they feed.
	Classification:GENUS	Name:Hesperocyon	Age:Early Oligocene to Early Miocene
	Locality:North America (Nebraska)	Size:2 ft 6 in/80 cm long	Fossil Name:
	Notes:An active little animal, looking like a mongoose or civet, Hesperocyon was one of the earliest members of the canid family to appear. With its long flexible body and tail, and its short, weak legs and spreading 5-toed feet, it may not have looked much like a dog. However, the structure of its ear bones and the arrangement of its teeth show without a doubt that it was a primitive canid. Fossils of the creature's skull show that parts of the inner ear were enclosed in bone rather than in cartilage (gristle) - a doglike feature that distinguishes Hesperocyon from more primitive carnivores, such as Miacis. The teeth of Hesperocyon show that the last molar tooth was missing from each side of the upper jaw, giving a set of 42 teeth rather than the usual complement of 44. The last upper premolar tooth and the first lower molar tooth on each side were modified into meatcutting (carnassial) blades, typical of dogs and most other true carnivores (that is, those grouped in the order Carnivora).
	Classification:GENUS	Name:Hesperornisregalis	Age:Late Cretaceous
	Locality:North America (Kansas)	Size:6 ft/1.8 m tall	Fossil Name:
	Notes:This large, flightless bird differed from other toothed seabirds in having lost its wings almost completely. It swam with powerful kicks of its large, webbed feet, set well back on the body, propelling itself along in the manner of a modern loon or grebe. Hesperornis regalis could have chased fast-moving fish and squid underwater, holding such slippery prey in its long bill, equipped with sharp, pointed teeth. It probably nested at the water's edge, like a modern loon, and it would have been clumsy and vulnerable while on land.
	Classification:GENUS	Name:Heterodontosaurus	Age:Early Jurassic
	Locality:Africa (South Africa)	Size:3 ft/90 cm long	Fossil Name:
	Notes:The rabbit-sized skull of Heterodoptosaurus was discovered in 1962 in South Africa's Cape Province, and a complete skeleton has since been found. In build, it was like a fabrosaur (above) - a small, lightweight, 2-legged plant-eater. Heterodontosaurus was, however, re, markable because of its teeth. They were unlike those of any other dinosaur and most other reptiles. Usually, a reptile's teeth are all the same size and shape. But Heterodontosaurus had 3 kinds of teeth - a dental pattern that is reminiscent of a mammal's, although Heterodontosaur had no connection with the mammalian line of evolution. At the front of the upper jaw, there were some small, pointed teeth (like a mammal's incisors). There were no opposing teeth at the front of the lower jaw-, instead, the chin bone carried a horny beak. This bone (known as the predentary) was unique to the ornithischian dinosaurs. No other reptile, or indeed any backboned animal, has this bone; usually, the 2 dentary bones that make up the lower jaw meet in the center to form the chin. Behind the upper teeth and the lower beak, Heterodontosaurus had 2 pairs of large, canine-type teeth (like the canines of a mammal). The lower pair fitted into a socket in the upper jaw. Behind these canines were the back teeth - tall, chisel-like teeth with cutting edges (comparable to a mammal's molars). Each type of tooth performed a different job. The pointed ones at the front combined with the beak to nip off leaves; the back teeth cut the leaves up with a scissorlike motion and ground them into small pieces. Nobody knows the function of this animal's canine teeth. Carnivorous mammals have canines for tearing apart flesh, but Heterodontosaurus was a planteater. Some skulls have been found that had no canines, or even sockets that would have contained them. This has led some paleontologists to suggest that only the males had canines, and that they used them for fighting each other. On the basis of this theory, those skulls without canines would have belonged to females.
	Classification:GENUS	Name:Hipparion	Age:Middle Miocene to Pleistocene
	Locality:Widespread in North America, Europe, Asia and Africa	Size:4 ft 6 in/1.4 rn high at the shoulder	Fossil Name:
	Notes:Once the plains-living grazing horses had evolved they, too, radiated into many different types. Of these, all but the Equus species are now extinct. Hipparion represents one of the many grazing horses that evolved during the Miocene, around 15 million years ago. It was particularly successful, spreading during the Miocene from North America into Asia, Europe and Africa. In Africa it survived until the Pleistocene about 2 million years ago. This elegant creature resembled the modern horse, but like Merychippus had 3 toes, 2 of which were much reduced and did not touch the ground.
	Classification:GENUS	Name:Hippidion	Age:Pleistocene
	Locality:South America	Size: 4 ft 6 in/1 -4 m high at the shoulder	Fossil Name:
	Notes:There seem to have been no horses in South America throughout the Tertiary. However, it cannot have been the environment that prevented their colonization, since conditions in South America were able to support the evolution of horselike litopterns such as Diadiaphorus (see pp. 246-249). When a land connection was re,established between North and South America during the Pliocene, 5 million years ago, horses were able to migrate and thrive there. Hippidion, probably a descendant of Merychippus, was one of these South American horses, It probably resem, bled a small donkey, with a fairly large head. However, its long, delicate nasal bones were quite distinct from those of other horses, suggesting that Hippidion continued to evolve in isolation from the mainstream of horse evolution in North America until it became extinct around 8000 years ago. The modern genus Equits, which includes the zebras and asses as well as the wild and domestic horses, seems to have evolved about 4 million years ago in North America, from where it migrated to Asia, Africa and Europe. Curiously, all the horses in the Americas died out about 8000 years ago, and did not reappear there until about 400 years ago and then only as a result of deliberate introduction by humans. Some paleontologists have speculated that their demise was caused by some devastating epidemic disease, possibly like myxomatosis.
	Classification:GENUS	Name:Hippopotamus	Age:Late Miocene to Recent
	Locality:Asia, Africa and Europe	Size:14 ft/4.3 m long	Fossil Name:
	Notes:The only obvious differences between a Hippopotamus gorgops of Pleistocene East Africa and the living species H. amphibius were its huge size and particularly prominent eyes. These eyes probably stuck up above the skull on stalks like periscopes, which would have given the animal good panoramic vision even while its whole body was submerged. Hippopotamus had the same familiar shape and heavy body which is more at home buoyed up in the water than it is on land, and equally broad feet for walking on mud. Its mouth, too, was wide, with characteristic huge tusks used for digging up water plants.
	Classification:GENUS	Name:Holoptychius	Age:Late Devonian
	Locality:Worldwide	Size:20 in/50 cm long	Fossil Name:
	Notes:Holoptychius was a deep-bodied, stream, lined fish, with a lightweight covering of thin, rounded scales. It was a voracious predator of other bony fishes. Like all its rhipidistian relatives, it had fanglike teeth arranged around the margin of its palate, and numerous smaller, pointed teeth lined both jaws. Prey would have been held fast between the teeth, then swallowed whole. Holoptychius had an asymmetrical tail. The powerful thrust produced by its upper lobe would have tended to drive Holoptychius down in the water. To com, pensate for this, the muscular pectoral fins were extra-long and mounted high on the flanks. They acted as hydrofoils; their slightest movement out to the sides would have elevated the front of the body, and counteracted the down, thrust produced by the tail. They also stabilized the fish and steered a course by their concerted movements.
	Classification:GENUS	Name:Homalocephale	Age:Late Cretaceous
	Locality:Asia (Mongolia)	Size:10 ft/3 m long	Fossil Name:
	Notes:Homalocephale means "even head," and refers to the fact that this pachycephalosaur did not have a dome on top of its skull. It had a rather flat, wedge-shaped head, although the bones of the skull cap were greatly thickened. There were numerous pits and bony knobs scattered all over the head. This has led some paleontologists to think that rival male Homalocephale fought the same kinds of ritualistic, head-butting battles as do the modern marine iguanas of the Galapagos Islands. Homalocephate had particularly broad hips, and paleontologists interpret this feature in different ways. Some say that the hips could have been part of the impact-absorbing system when rival males fought together. Others postulate that the broad hips could indicate that this bonehead gave birth to live young.
	Classification:GENUS	Name:Homalodotherium	Age:Early and Middle Miocene
	Locality:South America (Argentina)	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:The llama-sized Homalodotherium is the only well-known genus of the family. Unlike other notoungulates, Homatodotherium had a claw instead of a hoof on the four "fingers" of each "hand." The forelimbs were longer and heavier than the hindlimbs; and whereas the hind foot was plantigrade the forefoot was digitigrade. This made the animal higher at the shoulders than at the hips. Such features made it likely that Homatodotherium was partly bipedal. It probably browsed on the leaves of low branches, rearing up on to its hind legs.
	Classification:GENUS	Name:Homo crectus	Age: Early to Middle Pleistocene
	Locality:Africa (Tanzania, South Africa and Algeria), Europe (Germany, Spain, France, Greece and Hungary) and Asia (Java and China)	Size:about 5 ft 4 in/1.6 m tall	Fossil Name:
	Notes:H. erectus, or "upright human," was an outstandingly successful creature. Having evolved around 1.6 million years ago, it saw the extinction of all other hominids, including its possible ancestors A. afarensis or A. africanus, and survived until about 200,000 years ago. In bodily appearance, posture and gait, H. erectus must have been very similar to a modern human, although a little shorter. At 950 to 1200cc, the brain volume, too, was approaching the modern size, and areas of the brain associated with speech are welldeveloped. The head, however, still had heavy apelike eyebrow ridges and protruding jaws. H. erectus was evidently a wandering gatherer and hunter, moving about in groups but also creating settlements; a site in the south of France provides evidence of huts with brushwood walls supported on a framework of poles and anchored by stones. Tools were soph, isticated, and included spears, projectiles, blades, scrapers and choppers made from wood, stone, antler and bone. H. erectus also used fire for cooking and for defense. About half a million years ago, H. erectus left its birthplace in Africa and spread throughout the tropical, subtropical and temperate parts of the Old World. Remains have been found in so many places that a multitude of confusing common and scientific names have been applied, including Java and Pekin (Beijing) people, Pithecanthropus ('ape human") Sinanthropus ("China human") and Palaeanthropus ("old human"). All are now placed together in the same species.
	Classification:GENUS	Name:Homo habilis	Age: Early Plestocene
	Locality:Africa (Ethiopia, Kenya, Tanzania, possibly South Africa) and possibly Southeast Asia	Size: 4 to 5 ft/1-2 m to 1.5 m	Fossil Name:
	Notes:By about 2 to 1.5 million years ago, several hommids existed alongside one another in East Africa. Some were close enough to modern humans to be classed in the genus Homo. Homo habilis was still quite short and light, with less massive jaws and browridges. Its head too was larger than that of its predecessors, as was its brain (up to about 800 cc). The brain was also more complex - there is even some evidence from its structure that H. habilis could speak. However, the distinctive feature of H. habilis, or "handy human," is that it is the first hominid known to have fabricated tools. These mostly consisted of pebbles with a makeshift blade chipped out along one edge - other primates, for example Ramapithecus, probably used unmodified pebbles. There is also evidence of simple shelters, scavenging and hunting of game.
	Classification:GENUS	Name:HOMO Sapiens "Cro-Magnon"	Age:Late Pleistocene to Recent
	Locality:Worldwide	Size:5 ft to 6 ft/1.5 m to 1.8 m tall	Fossil Name:
	Notes:The modern subspecies of H. sapiens is well known throughout the world from about 35,000 years ago. Artefacts and cave paintings found in central France, dating from about 30,000 years ago, testify to their cultural sophistication. These remains of "Cro-Magnon people" suggest that they had a strong tribal system, made tools, gathered plant materials, hunted, fished and possibly herded animals, and built shelters and manufactured clothing that enabled them to survive the last stages of the Pleistocene Ice Age. Soon afterward, about 10,000 years ago, peoples in many different parts of the world independently developed a farming lifestyle. Animals were domesticated, crops planted, a more sedentary lifestyle developed, and populations grew. Thereafter the ability to modify the natural environment has led Homo sapiens to the dominant position it currently enjoys.
	Classification:GENUS	Name:Homo sapiens neanderthalensis	Age:Late Pleistocene
	Locality:Europe (Mediterranean region) and Asia (Israel)	Size: up to 5 ft 7 in/1.7 m tall	Fossil Name:
	Notes:H. sapiens neanderthalensis, the "wise person from the valley of the River Neander," is named for a site in Germany where skeletons were discovered in 1856. Many fossils have been dis, covered from Gibraltar and North Africa in the west, throughout the Near East, and east to central Asia. Neandertal people evolved around 250,000 years ago. They were very succe~,sful during the warm periods toward the end of the Pleistocene Ice Age, but probably died out around 30,000 years ago. Although they may have interbred with later, more advanced migrants from Africa, it now seems more likely that they represent a side-branch of the human family. Their bodies were short and powerfully built, they had large hands and joints, and a rather broad head, a flat or bulbous nose, and prominent eyebrows. The brain capacity, often in excess of 1400 cc, was in fact on average greater than that of modern humans. Neandertal people were highly soph, isticated, with a well,developed tool technology. They also show the begin-, nings of what has been thought of as a religious culture. For example, they buried the dead and clearly treated the cave bear, Ursus spelaeus, with reverence.
	Classification:GENUS	Name:Homotherium	Age:Early to Late Pleistocene
	Locality:Africa (Ethiopia), Asia (China and Java), Europe (UK) and North America (Tennessee and Texas)	Size:4 ft/1.2 In	Fossil Name:
	Notes:Besides sabertooth and dirktooth cats, there were also scimitartooth cats, so called because their death-dealing canines were shorter and flatter than those of the sabertooths. They also curved backward, like a scimitar's blade. The back teeth consisted of powerful, meat,shearing (carnassial) blades for slicing up flesh. In profile, Hornotherium must have had the sloping look of a hyena, since its forelegs were longer than its hindlegs. When it walked, the whole foot was placed firmly on the ground, as in a bear or a human. This is called "plantigrade" locomotion, and contrasts with most other cats, which walk on their toes (called "digitigrade" locomotion). Homotherium survived until the end of the last ice age in the Pleistocene, about 14,000 years ago. Scimitartooth cats probably preyed on mammoths, since in Texas the remains of young mammoths have been preserved alongside the bones of a family group of scimitartooths. Hornotherium may have become extinct when its prey died out in the northern continents at the end of the Pleistocene ice age.
	Classification:GENUS	Name:Hovasaurus	Age:Late Permian
	Locality:Madagascar	Size:20 in/50 cm long	Fossil Name:
	Notes:The most striking feature of this aquatic lizardlike reptile was its tail. Not only was it twice the length of the rest of the body; it was also deep and flattened from side to side. Each of the tail vertebrae was extended above and below the midline. The result was a tail that formed a broad, stiff paddle, allowing Hovasaurus to swim efficiently. Another unusual feature of Hova- saurus is the mass of pebbles found in the abdominal cavities of most of the specimens recovered. Evidently, these reptiles swallowed stones as ballast, to help them sink quickly in the water when diving for their fish prey, or to keep them submerged when feeding.
	Classification:GENUS	Name:Hyaenodon	Age: Late Eocene to Early Miocene
	Locality:Widespread over North America, Europe (France), Asia (China) and Africa (Kenya)	Size:Up to 4 ft/1.2 m long	Fossil Name:
	Notes:The hyaenodonts, the later of the 2 families of creodonts, were a much larger group than the oxyaenids. They evolved in the Eocene and persisted to the Late Miocene. They ranged from North America, to Asia, Europe and Africa. Hyaenodon was a widespread and long-lived genus. There were many species, from animals the size of a stoat to species as large as a hyena. It probably evolved in Europe or Asia and later migrated into North America and Africa. Its long, slim legs and digitigrade feet (in which only the toes touched the ground) indicate that Hyaenodon could run, though its spreading toes suggest that it would not have been very fast. Hyaenodon may have been hyenalike in habits, actively hunting down other animals but also scavenging dead ones.
	Classification:GENUS	Name:Hybodus	Age:Late Permian to Late Cretaceous
	Locality:Worldwide	Size:6 ft 6 in/2 m long	Fossil Name:
	Notes:Hybodus was one of the most common, widespread and long-lived types of fossil shark. It looked essentially like a modern Blue shark, although only half its size and with a blunter snout. It had two types of teeth in its powerful jaws, suggesting a varied diet. Pointed teeth at the front seized and pierced its fish prey, while the blunt, low-crowned teeth at the back crushed their bones, and also the hard shells of bottom-living snails, sea urchins, crustaceans and shellfish. Hybodus and its relatives gained (and their descendants have retained) a reproductive advantage over other fishes. Part of the pelvic fins in the male shark were modified into erectile, penislike organs, called "claspers" (seen in the illustration of Hybodus on p. 26). These were inserted into the female during copulation, and sperm was transferred directly into her body - a superior method of fertilizing eggs than the wasteful shedding of sperm into the open sea practised by most bony fishes.
	Classification:GENUS	Name:Hydrodamalis gigas	Age:Pliocene to Recent
	Locality:Arctic and North Pacific oceans	Size:26 ft/8 m long	Fossil Name:
	Notes:This enormous sirenian, only recently extinct, was known as Steller's sea cow, for Georg Steller, the German naturalist, who discovered it in 1741. A former member of the clugong family, Hydrodamalis gigas evolved toward the end of the Pleistocene, about 200,000 years ago, but became extinct (due to hunting) as recently as 1768. Its large size was probably an adaptation to the very cold waters of its northern range. (A large animal retains heat better than a smaller one, which has a greater surface area relative to its size.) Steller's sea cow had lost the thickened ribs of other sirenians, and had developed great layers of blubber, covered by a thick, barklike skin, to serve as insulation against the cold. As a result, the animal was probably too buoyant to dive. Lacking teeth entirely, it fed on floating seaweed - a diet unique among mammals.
	Classification:GENUS	Name:Hylacosaurus	Age:Early Cretaceous
	Locality:Europe (England)	Size:20 ft/6 m long	Fossil Name:
	Notes:This is the earliest creature that can definitely be identified as a nodosaur. It was first found in Sussex in southern England in the late 1820s, and named by that English pioneer of paleontology, Gideon Mantell, in 1832. To this day, its bones are still imprisoned in the slab of rock in which they were fossilized, but there are now plans to extract the skeleton with the use of acetic acid. This dissolves away the mineral calcite, which cements together the particles of rock, so releasing the fossilized bones. Until new evidence is available, the restoration of Hylaeosaurus on p. 155 must remain speculative. The narrow head, armor-plated body and tail, and the outwardly projecting spikes on the flanks were typical nodosaur features.
	Classification:GENUS	Name:Hylonomus	Age:Late Carboniferous
	Locality:North America (Nova Scotia)	Size:8 in/20 cm long	Fossil Name:
	Notes:Hylonomus is the earliest-known, fullyadapted terrestrial vertebrate - a milestone in the evolution of life on land. In appearance and lifestyle, it closely resembled a modern lizard. This small creature probably ate insects and other invertebrates, crushing them with its conical teeth. Though the teeth were simple and unspecialized, some of the front ones were longer than the rest - a feature usually found in the more advanced reptiles. Hylonomus was preserved in the coal beds of Nova Scotia in an unusual way. Giant, treelike club mosses flourished in swampy areas during Late Carboniferous times. Periodic flooding buried their lower trunks in deep layers of mud and rotting leaf litter, which caused the trees to die and their interiors to rot away. This left deep, cylindrical cavities in the ground, which would have filled up with decaying debris. Insects and other invertebrates would have been attracted there, and these in turn would have attracted Hylonomus. It would have been unable to escape from the deep, vertical-sided cavities, and its remains were eventually fossilized there.
	Classification:GENUS	Name:Hypacrosaurus	Age:Late Cretaceous
	Locality:North America (Alberta and Montana)	Size:30 ft/9 m long	Fossil Name:
	Notes:Another duckbill with a prominent semicircular crest on its head was Hypacrosaurus. The crest was similar to that of Corythosaurus, but not so tall or narrow. Nor did it rise so steeply from the animal's face, but rather sloped upward in a gentle curve. Since Hypacrosaurus is found in slightly later rock deposits than Corythosaurus, it is possible that it evolved from that duckbill. Another difference between these 2 similar-sized duckbills was that the back vertebrae of Hypacrosaurus were extended upward into tall spines, which would have formed a prominent, skincovered ridge down the animal's back. The function of this ridge may have been to regulate body temperature, operating in the same way as that proposed for other reptiles, such as the finbacked pelycosaurs (see pp. 186-189) or the carnivorous spinosaurs (see p. 120).
	Classification:GENUS	Name:Hyperodapedon	Age:Late Triassic
	Locality:Asia (India) and Europe	Size:4 ft/1.3 m long	Fossil Name:
	Notes:Hyperodapedon was a member of the rhynchosaur group of early reptiles. They were all heavy, barrel-shaped plant-eaters, which thrived from the Middle to Late Triassic. They were the most abundant reptiles of the day, especially in South America and Africa. The success, though short-lived, of Hyperodapedon and its rhynchosaur relatives can be attributed to their teeth. There were 2 broad tooth plates on each side of the upper jaw. Each plate contained several rows of teeth, and a groove ran down the middle. The 2 single tooth rows of the lower jaws fitted into this groove when the mouth was closed, to give a chopping action. Rhynchosaurs would have feasted on seed ferns, everywhere abundant during the Triassic. But these plants died out at the end of that period, and were replaced by conifers. The rhynchosaurs died out, too, and their herbivorous niche was taken by the newly evolved, plant-eating dinosaurs. The "Age of Ruling Reptiles" had begun.
	Classification:GENUS	Name:Hypsidoris	Age:Eocene
	Locality:North America (Wyoming)	Size:8 in/20 cm long	Fossil Name:
	Notes:Early in the Tertiary, a group of fishes (called the Ostariophysi) diverged from the main teleost line, and became specialized for life in freshwaters, though some groups later returned to the sea. Today, more than 6000 species survive, including the carp, minnow, goldfish, loach, piranha and catfish. Hypsidoris was strikingly similar to a modern catfish. It lived in the subtropical rivers and lakes of western North America some 50 million years ago. Many excellent specimens have been preserved in the Green River deposits of Wyoming, laid down in the Eocene. The structure of Hypsidoris'backbone indicates that it had the acute hearing (especially of high-frequency sounds) characteristic of all living ostariophysid fishes. This sensitivity to sound is due to a unique specialization of the vertebrae at the front of the backbone in these fishes. The vertebrae are modified into a chain of small, movable bones, which transmit vibrations picked up by the swim bladder (which acts as a hydrophone and resonator) to the inner ear. There, they are interpreted by the brain as either potential prey or approaching predator. These sound-transmitting bones in fishes are called the Weberian ossicles, and serve a similar function to the hammer-anvil-stirrup chain in the middle ear of mammals. Like its modern relatives, Hypsidoris had a stout spine at the front edge of each pectoral fin. These spines were defensive, and could be erected by powerful muscles in times of need. Prey was located, or danger sensed, by its acute hearing - a valuable asset in the often dark and murky waters of the sediment-laden rivers in which it lived. Having homed in on the potential prey, its edibility was assessed at closer quarters by the long, sensory filaments surrounding the catfish's mouth. These "feelers" were sensitive to touch and to chemical substances in the water. Fish were Hypsidoris' chief prey, but crayfish and other bottom-dwellers were also detected by the trailing feelers.
	Classification:GENUS	Name:Hypsilophodon	Age:Early Cretaceous
	Locality:Europe (England and Portugal) and North America (South Dakota)	Size:5 ft/1.5 m long	Fossil Name:
	Notes:About 20 perfect skeletons of this small hypsilophodont were found in one particular bed of Lower Cretaceous rocks in the Isle of Wight, off southern England. This find probably represents a herd of animals that lived and died together, perhaps overwhelmed by the rising tide of the shallow seas that lay over northern Europe some 120 million years ago. Hypsilophodon is the classic representative of the family, and has given its name to the whole group. Its name means "high ridge tooth," and refers to the tall, grooved cheek teeth typical of all hypsilophodonts. The upper and lower teeth met to form a flat surface for grinding up plant food. Oddly enough, in comparison with its earlier relatives of the Late Jurassic (see Dryosaurus, p. 140), Hypsilophodon had certain primitive features. For example, it had 4 toes on each foot, and there were incisor-type teeth at the front of the upper jaw. When these were closed on the toothless, horny beak of the lower jaw, they formed an effective device for cropping vegetation. Hypsilophodon may also have been armored, with 2 rows of thin, bony scales running down either side of its back. But paleontologists are uncertain about this feature. The study of Hypsilophodon since its discovery in the 19th century is a classic story of paleontological research. When it was first described, by Thomas H. Huxley in 1870, paleontologists of the day were struck by the similarity of its build to that of a modern tree kangaroo. For almost a century, classic illustrations of Hypsilophodon showed it perched in a tree, 3 of its 4 toes gripping the branch, birdlike, and the fourth toe directed backward. This reconstruction neatly filled an ecological niche not yet occupied by any dinosaur, and so, the idea of a tree-dwelling, plant-eating ornithopod was conceived. It was not until 1974 that the skeleton of Hypsilophodon was reassessed. Paleontologists concluded that there was no evidence to show that this dinosaur lived in trees. In fact, it was a perfectly adapted terrestrial animal, capable of running rapidly on 2 legs.
	Classification:GENUS	Name:Hypsocormus	Age:Middle to Late Jurassic
	Locality: Europe (England and Germany)	Size:up to 3 ft 3 in/1 In long	Fossil Name:
	Notes:The dividing line between the advanced neopterygians and the primitive teleosts is unclear. Hypsocormus was a fast,swimming, fish-eating predator, which could have belonged to either group since it had both primitive and advanced features. For example, it had the heavy, "oldfashioned" body armor of its palaeoniscid ancestors - thick, enamel-covered, rectangular (rhomboid) scales. But the scales were comparatively smaller and allowed greater flexibility during swimming. Its tail was symmetrical and halfmoon,shaped, superficially like that of a modern mackerel, although there were many more bony fin rays supporting the lobes of the tail than in modern teleosts. Its fins, too, were arranged differently on the body. Besides the long anal fin, there was only one dorsal fin. The extralarge pectoral fins were placed low on either side (rather than high up on the flanks, behind the gills, as in more advanced bony fishes). And the pelvic fins were unusually small and placed halfway down the belly. Hypsocormus did, however, have fairly advanced jaws. They were flexible and mobile, and well equipped with muscleattachment points to ensure a powerful bite. The upper and lower jaw bones were long, and equipped with teeth along their length.
	Classification:GENUS	Name:Hypsocormus	Age:Middle to Late Jurassic
	Locality:Europe (England and Germany)	Size:up to 3 ft 3 in/1 In long	Fossil Name:
	Notes:The dividing line between the advanced neopterygians and the primitive teleosts is unclear. Hypsocormus was a fast,swimming, fish-eating predator, which could have belonged to either group since it had both primitive and advanced features. For example, it had the heavy, "oldfashioned" body armor of its palaeoniscid ancestors - thick, enamel-covered, rectangular (rhomboid) scales. But the scales were comparatively smaller and allowed greater flexibility during swimming. Its tail was symmetrical and halfmoon,shaped, superficially like that of a modern mackerel, although there were many more bony fin rays supporting the lobes of the tail than in modern teleosts. Its fins, too, were arranged differently on the body. Besides the long anal fin, there was only one dorsal fin. The extralarge pectoral fins were placed low on either side (rather than high up on the flanks, behind the gills, as in more advanced bony fishes). And the pelvic fins were unusually small and placed halfway down the belly. Hypsocormus did, however, have fairly advanced jaws. They were flexible and mobile, and well equipped with muscleattachment points to ensure a powerful bite. The upper and lower jaw bones were long, and equipped with teeth along their length.
	Classification:GENUS	Name:Hypsognathus	Age:Late Triassic
	Locality:North America (New Jersey)	Size:13 in/33 cm long	Fossil Name:
	Notes:One of the later members of the family, Hypsognathus had many features that,,, indicate it was a plant-eater. It had a wide, squat body, which suggests that it was not an agile animal. Its broad cheek teeth were suitable for grinding tough plant material. And an arrayl spikes around its head were probab for defense against predators, such the contemporary carnivorous din saurs, the podokesaurs (see p. 108).
	Classification:GENUS	Name:Hyrachyus	Age:Early to Late Eocene
	Locality:North America (Wyoming), Asia (China) and Europe (France)	Size:5 ft/1.5 m long	Fossil Name:
	Notes:Hyrachyus was generally, very similar to Heptodon, but a little larger and more heavily built. It was a and widespread animal. Many species are known, ranging from the size of a modern tapir to that of a fox. Hyrachus appears to be ancestral to both the later tapirs and the rhinoce, roses. Indeed, its resemblance to a primitive form of the latter group is so pronounced that it is often classed as rhinoceros, albeit a lightweight one
	Classification:GENUS	Name:Hyracodon	Age:Early Oligocene to Early Miocene
	Locality:North America (Saskatchewan, Dakota, Nebraska)	Size: 5 ft/1.5 m long	Fossil Name:
	Notes:Hyracodon was a lightly-built fastrunning animal, not unlike a pony. As with the horses, the number of toes were reduced, so that the foot was lightened and could be moved quickly, and all the leg muscles were concentrated near the top. There were 3 toes on all feet. The large and heavy head, however, seemed out of proportion to the body. No horns had evolved at this stage, and the only means of defense against such local meat-eaters as Hyaenodon, the last of the creodonts, or the early dogs would have been to flee. The back teeth were of a typical rhinoceros pattern, low, crowned and adapted for chewing leaves.
	Classification:GENUS	Name:Hyracotherium	Age:Early Eocene
	Locality:Widespread in Asia, Europe, and North America	Size:8 in/20 cm high at the shoulder	Fossil Name:
	Notes:In spite of its name, Hyracotherium is not a close relative of the hyraxes - this is the result of mistaken identification in the last century. A more evocative name, Eohi pus, h "dawn horse," has been suggested, bu science retains the earlier term.
	Classification:GENUS	Name:Icaronycteris	Age:Early Eocene
	Locality:North America (Wyoming)	Size:51 in/14 cm. long, 14 in/37 cm wingspan	Fossil Name:
	Notes:Icaronycteris must have been almost identical to a modern microbat, but still had a few very primitive features. Its wings were relatively short and broad, and its mouth contained a large number of teeth, arranged like those of an insectivore (see p. 196). The body was not quite as rigid as that of a modern bat, and the tail was long and not connected to the hind legs by a web of skin. The thumb and first finger each bore a claw - modern bats have a claw only on the thumb - for hanging vertically from cave walls or other supports. Even at this early stage in their evolution, bats roosted upside down. Icaronycteris undoubtedly lived like the modern microbats, catching insects on the wing, probably while flying low over water in the evening when there were few birds around. Some remarkably well-preserved bats are known from the Middle Eocene oil shale deposits of Messel near Frankfurtam-Mein in Germany. Even the wing membranes are still visible, and remains found in the area of the bat's stomach confirm it was an insect-eater.
	Classification:GENUS	Name:Ichthyornis dispar	Age:Late Cretaceous
	Locality:North America (Kansas and Texas)	Size:8 in/20 cm tall	Fossil Name:
	Notes:First discovered in the 1870s, the toothed jaws of this ancient bird were originally thought to belong to a mosasaur - a contemporary, fisheating marine lizard (see p. 88). This reptile was preserved in the same rocks, and had similar jaws and teeth to those of Ichthyornis. Ichthyornis dispar and others of its genus had a general structure like that of a large, modern sea tern, but with a proportionally bigger head and bill. The large sternum suggests strong flight.
	Classification:GENUS	Name:Ichthyosaurus	Age:EarlyJurassic to Early Cretaceous
	Locality:Europe (England and Germany), Greenland and North America (Alberta)	Size:up to 6 ft 6 in/2 m long	Fossil Name:
	Notes:Ichthyosaurus is one of the best-known prehistoric animals, since a graphic record of its remains are preserved in the shales of southern Germany, near Holzmaden. These rocks were laid down in shallow waters during the Early Jurassic. Several hundred complete skeletons of Ichthyosaurus have been found, their bones still articulating with each other. The tiny bones of their young were also found inside the bodies of several adults. This - combined with some specimens where the young is preserved actually emerging from the body of the adult (tail-first, as in modern whales) shows without a doubt that these marine reptiles gave birth to live young at sea. The find in Germany also yielded a unique picture of how the animals looked in life. A thin film of carbon had been laid down around many of the specimens, outlining the exact shape of their bodies when the flesh was still on the bones. The characteristic features of a typical ichthyosaur can be clearly seen - the high dorsal fin on the back; the half-moon shape of the tail (caudal) fin, with the backbone angled down sharply into its lower lobe; and the short, hydrofoil-shaped paddles that enclosed the greatly elongated toes of the limbs, the front pair longer than the hind pair. The nostrils of Ichthyosaurus were set far back on its snout near the eyes, so the animal only had to break the surface of the water to breathe. The bones of the ear were massive, and probably transmitted vibrations from the water to the inner ear, so that the direction of potential prey could be judged. But Ichthyosaurus' main sense for locating its prey would have been sight - its eyes were large and, most probably, extremely sensitive. Even fossil droppings (called coprolites) and stomach contents of these marine reptiles have been preserved in the rocks. They confirm that fish constituted the bulk of the diet, but that cephalopods were also eaten, such as the straight-shelled belemnites. The remains of pigment cells have also been preserved, and analysis of these suggests that the smooth, thick skin of Ichthyosaurus was a dark reddishbrown color in life.
	Classification:GENUS	Name:Ictitherium	Age:Middle Miocene to Early Pliocene
	Locality:Africa (Morocco) and Europe (Greece)	Size:4 ft/1.2 m	Fossil Name:
	Notes:Ictitherium was one of the earliest hyenas, and probably looked more like a civet (a relative of the mongooses and genets) in build and appearance. It also had teeth like those of a civet, suited to an insectivorous diet, rather than the formidable bonecrunching teeth of hyenas. Along with its primitive relatives, Ictitherium was among the most wide, spread hunters of its time. Indeed, at one stage during the Pliocene its fossil remains outnumber those of all other carnivores put together. Groups of animals are often found fossilized together, which suggests that a flood swept them away at the same time. It is likely that this early hyena had already evolved a relatively advanced social order and hunted in packs, as. hyenas do today.
	Classification:GENUS	Name:Ifingoceros	Age:Late Miocene
	Locality: North America (Nevada)	Size:6 ft/1.8 m long	Fossil Name:
	Notes:The various antilocaprids differ from one another in the shape and arrangement of the horns. Ilingoceros, which was slightly larger than the living pronghorn, had a pair of spirallytwisted horns which grew straight upward and ended in a slight fork. Other forms include Osbornoceros, with smooth, slightly curved horns; Paracosoryx, with flattened horns widening to a forked tip; Ramoceros, with extraordinary vertical fan,shaped horns, and the particularly well-endowed Hayoceros.
	Classification:GENUS	Name:Iguanodon	Age:Early Cretaceous
	Locality:Europe (eg England, Belgium and Germany), North America (Utah), Africa (Tunisia) and Asia (Mongolia)	Size:30 ft/9 m long	Fossil Name:
	Notes:Iguanodon rightly deserves its place in dinosaur lore. It was the second dinosaur to be discovered, although the word "dinosaur" had yet to be invented (see p. If 7). Part of its great shin bone was found in southern England in 1809, and then some teeth and other bones were discovered in 1819. Scientists of the day regarded the teeth as belonging to some giant mammal, like a rhinoceros. But Gideon Mantell, a geologist and keen fossil collector, saw that the teeth were reptilian, and that they resembled those of the modern iguana of Central and South America. So he named the animal Iguanodon, and de- scribed it in 1825 to the scientitic community. Mantell attempted a restoration, but with the sparse information he had to hand, it was speculative. He reconstructed Iguanodon as a 4-legged, dragonlike beast, with a heavy tail and small, lizardlike head. He placed a short horn on the animal's snout - this was actually one of the animal's "thumbs" (below). It was not until 1877 that the true nature of Iguanodon became apparent. During that year, in the small town of Bernissart in Belgium, the massive bones of what turned out to be 31 Iguanodon were found by workers tunneling through a coalmine. These srectacular skeletons are now restored and on display in the Royal National Institute of Natural Sciences in Brussels. Iguanodon stood 16 ft/5 m tall, measured 30 ft/9 In in length, and probably weighed about 5 US tons/4.5 tonnes. Herds of Iguanodon would have roamed the warm, tropical Cretaceous landscape, browsing on low-growing ferns and horsetails near rivers and streams. They would have spent much of their time on 4 legs; they could also walk upright, and reach higher vegetation, using their long outstretched tails to prop up or balance their bodies. The head of this great dinosaur ended in a prominent snout and powerful, beaklike jaws. The cheek teeth would have provided a strong, grinding action, because the bones of the upper jaw could move apart when the lower jaw was raised up between them. Then, the banks of cheek teeth moved past each other, pulverizing the plant food. The legs were long and pillarlike, each with 3 stout toes, ending in heavy, hooflike nails. Each short arm had a 5, fingered hand, which could be splayed wide, and used for walking when the animal was on all-fours. Three of the fingers had hooflike nails. The fifth, or "little," finger was flexible enough to have been used for grasping or hooking down leaves to the mouth. The first finger' or "thumb," was developed into a prominent spike, which stuck out Sideways from the hand. In 1825, Mantell had found only one of these thumb spikes, and, not knowing which part of the animal it came from, placed it, incorrectly, on the snout as a horn. The function of these thumb spikes is not known. They could have been used to tear down foliage. Or they could have been used to defend itself against attacks from contemporary predators like Megalosaurus (see p. 117). Or, perhaps, the spikes were sexual display structures, used in courtship and mating. Like Megalosaurus, Iguanodon has left its footprints in the rocks of southern England. Great trackways suggest that the animals were walking upright at the time they passed, and were traveling in a herd. Similar footprints, though no actual bones, have also been found in South America and in Spitzbergen, north of today's Arctic Circle, which shows how widespread Iguanodon must have been 100 million years ago.
	Classification:GENUS	Name:Imagotaria	Age:Late Miocene
	Locality:North America (Pacific coast)	Size: 6 ft/1.8 in long	Fossil Name:
	Notes:Although Imagotaria is classed as a walrus, it probably looked and behaved like a sealion. It may represent a transitional stage in the evolution of the sealions and walruses. The canine teeth, which are used by sealions to catch fish, had begun to enlarge, but not to the extent of forming the distinctive tusks used by walruses to dig up shellfish. Nor had the back teeth evolved into the broad shell-crushers of modern walruses. It therefore probably fed on both fish and shellfish.
	Classification:GENUS	Name:Indricotherium	Age:Oligocene
	Locality:Asia (Pakistan and China)	Size:26 ft/8 m long	Fossil Name:
	Notes:It seems quite impossible that an animal as small, lightweight and fleet-of-foot as Hyracodon could have evolved into the largest land mammal known to have lived, but all of the evidence points in that direction. Indricotheriurn - also known as Baluchitherium after the state in Pakistan in which major specimens were discovered - was an immense animal. With an estimated weight of 33 tons/30 tonnes, it was twice the weight of the largest known mammoth and more than 4 times that of the heaviest modern elephant. The skull itself was 4 ft 3 in/ 1. 3 in long, but this was relatively small compared to the overall body size. The vertebrae of the back and the long neck were sculpted into hollows and struts, like those of the largest dinosaurs, which kept weight down while retaining the strength. The legs were elephantine, but the entire weight would have been supported on only 3 toes - the normal rhinoceros pattern. Again, there was no horn; in fact, the nasal bones were quite weak. The front teeth of the fossil rhinoce, roses varied widely, but those of Indricotherium were very strange indeed. There were only 2 front teeth on top and 2 below: the upper pair pointing downward like tusks, while the lower pair pointed forward. Since there is some evidence that it had a large, flexible upper lip, such a construction would have enabled Indricotherium to browse giraffelike from the tops of trees more than 26 ft/8 in from the ground. Indricotheriurn probably lived in small family groups, taking advantage of the scattered trees found in dry open woodlands. One skeleton was discovered in rocks formed from swamp mud. It is easy to imagine the difficulties such a huge crea, ture would have had in a bog.
	Classification:GENUS	Name:Ischyodus	Age: Middle Jurassic to Paleocene
	Locality: Europe (England, France and Germany) and New Zealand	Size:5 ft/1.5 rn long	Fossil Name:
	Notes:Ischyodus, more than 150 million years old, was practically identical in size and shape to Chimaera monstrosa, the modern ratfish found in the depths of the Atlantic and Mediterranean. It had the same large eyes, pursed lips, tall dorsal fin, fanlike pectorals and whiplash tail of its living relative. It even had a similar spine in front of the dorsal fin, which in the living species is connected to a venom gland, and used for defense.
	Classification:GENUS	Name:Ischyromys	Age:Early Eocene
	Locality:North America	Size:2 ft/60 cm long	Fossil Name:
	Notes:Ischyromys is among the earliest known true rodents. Mouselike in appearance, it had many typical rodent head fea, tures, including the characteristic pair of upper incisors. The rest of the body was that of a typical rodent as well, with versatile forelimbs, strong hindlimbs and 5 clawed toes on all feet. While many of the other early Tertiary mammals were occupying the terrestrial niches, all the evidence suggests that Ischyromys and its more squirrellike relative Paramys were taking advantage of the possibilities presented by trees. As the most advanced climbing animals of their time, they eventually displaced the primitive rodentlike primates which had existed there from Paleocene times.
	Classification:GENUS	Name:Jamoytius	Age:Late Silurian
	Locality:Europe (Scotland)	Size:11 in/27 cm long	Fossil Name:
	Notes:Named for the English paleontologist J. A. Moy-Thomas, the marine Jamoytius had a narrow, tubular shape, with a long fin on its back, a pair of lateral fins running along its flanks and a small anal fin. Uplift was produced by the strongly downturned tail. Jamoytius had a round, suckerlike mouth, and it was probably a parasite like its living descendant, the marine lamprey. This jawless fish attaches itself to other fishes, rasps away their fiesh and then sucks their blood.
	Classification:GENUS	Name:Kannerneyeria	Age:Early Triassic
	Locality:Africa (South Africa), Asia (India) and South America (Argentina)	Size:up to 10 ft/3 m long	Fossil Name:
	Notes:This ox-sized dicynodont was a welladapted land-living herbivore. Its limb girdles formed massive plates of bone, to support the bulky body. Kannemeyeria's head was massive, but lightweight, due to the great size of the openings for the eyes, nostrils and jaw muscles. The powerful, horny beak would have torn up great mouthfuls of leaves and roots, to be ground down by the shearing action of the toothless jaws. A skull bone of Kannemeyeria, or a close relative, was found in Australia in 1985, adding to the mass of biological evidence for Gondwanaland.
	Classification:GENUS	Name:Kanuites	Age:Miocene
	Locality:Africa (Kenya)	Size: 3 ft/90 cm. long	Fossil Name:
	Notes:The viverrids have changed remarkably little during their long evolution, and Kanuites doutless appeared very similar to the existing genets (Qenetta). It had a long tail and perhaps retractable claws i like those of a cat. It was probably omnivorous, feeding on fruit, insects, small mammals and reptiles, and may have lived in trees as well as on the ground.
	Classification:GENUS	Name:Karaurus	Age:Late Jurassic
	Locality:Asia (Kazakhstan SSR)	Size:8 in/20 cm long	Fossil Name:
	Notes:Salamanders seem to have changed little over the known 150 million years of their evolution. The structure of the oldest-known salamander, Karaurus, is practically the same as that of modern forms. Its lifestyle was presumably similar, also - a good swimmer and a voracious predator of snails, worms, crustaceans and insects.
	Classification:GENUS	Name:Kentrosaurus	Age:Late Jurassic
	Locality:Africa (Tanzania)	Size:16 ft/5 m long	Fossil Name:
	Notes:Well-preserved remains of this East African stegosaur - a contemporary of the North American Stegosaurus - have been found in modern Tanzania among the fossil-rich deposits of Tendaguru Hill. Kentrosaurus was not as large as its American relative, but it was at least as well armored. A double row of narrow, triangular, bony plates rose on either side of the backbone, grouped in pairs along the neck, shoulders and front part of the back. The plates were then re, placed by pairs of sharp spikes (some of them about 2ft/60cm long) that ran down the lower back right to the tip of the tail. In addition, a pair of extra-long spikes stuck out at hip-level on each side, affording good protection should a predator attack from the side.
	Classification:GENUS	Name:Keraterpeton	Age:Late Carboniferous
	Locality:Europe (Czechoslovakia) and North America (Ohio)	Size:1 ft/30 cm long	Fossil Name:
	Notes:The tail of Keraterpeton was more than twice the length of its body and head combined. It was flattened sideways, and would have provided the propulsive force that pushed the animal through the murky waters of the coal swamps in which it lived. The 5-toed hindlegs were longer than the 4-toed forelegs. The skull was short and rounded, with the eyes far forward. Although its body was long and slender, Keraterpeton had no more trunk vertebrae than usual (15-26 on average), unlike other long-bodied amphibians, such as the anthracosaur Eogyrinus which had some 40 vertebrae in front of the hips (see pp. 51, 53).
	Classification:GENUS	Name:Kritosaurus	Age:Late Cretaceous
	Locality:North America (Alberta, Montana and New Mexico)	Size:30 ft/9 m long	Fossil Name:
	Notes:Kritosaurus was a typical flat-headed duckbill. Although it had no crest on its head, there was the beginnings of one, developed as a large, bony hump on the snout in front of the eyes. The function of this hump of solid bone is unknown. It could have been a sexual display structure possessed by the males only, and used in courtship and mating. Alternatively, it could have served the same purpose as the thickened skull caps of the pachycephalosaurs (see p. 137) - to absorb the impact when rival males crashed headon in their ritualistic, head-butting battles, which took place at the beginning of each season to decide leadership of the herd, and control of the harem. Some paleontologists think that Kritosaurus and Hadrosaurus (below) are different species of the same animal.
	Classification:GENUS	Name:Kronosaurus	Age:Early Cretaceous
	Locality:Australia (Queensland)	Size:42 ft/12.8 rn long	Fossil Name:
	Notes:The Australian Kronosaurus is the largest-known pliosaur. Its skull was flat-topped and massively long, measuring 9 ft/2.7 m - almost a quarter of the total body length, and therefore substantially larger and more powerful than that of the greatest carnivorous dinosaur, Tyrannosaurus (see pp. 118-121). Throughout the Triassic and Jurassic periods, the modern continent of Australia had been dry land, but in the early part of the Cretaceous, the seas flooded in to submerge many areas. The environment was warm and the seas shallow, and these conditions would have supported large populations of fish and their cephalopod predators. Kronosaurus and other short-necked pliosaurs were highly maneuverable swimmers, and they would have found rich feeding grounds in these shallow seas.
	Classification:GENUS	Name:Kuehneosaurus	Age:Late Triassic
	Locality:Europe (England)	Size:26 in/65 cm long	Fossil Name:
	Notes:This was a long-legged lizard that could glide through the air on a pair of membranous "wings." These projected out from each side of its body, between the front and hindlimbs, and spanned more than 1 ft/30 cm. The greatly elongated ribs formed the framework for the skin-covered gliding membranes. This was exactly the same arrangement developed by an earlier type of diapsid reptile - the gliding Coelurosauravus (see pp. 82, 84). And the same pattern occurs in a living lizard the flying dragon, Draco volans, of Southeast Asia. This modern forestdweller, only 8 in/20 cm long, can glide on similar skin flaps to those of the extinct Kuehneosaurus - a single glide can cover up to 200 ft/60 m, losing only 6 ft 6 in/2 In in height over that distance. Its ribs are movable, and so it can fold its wings against the body when at rest.
	Classification:GENUS	Name:Kvabebihyrax	Age: Late Pliocene
	Locality: Europe (Caucasus)	Size:5 ft 3 in/1.6 m long	Fossil Name:
	Notes:The great difference between the fossil types of hyrax and the modern animals can be seen in Kvabebihyrax. With its stout body and small eyes set high upon the skull, Kvabebihyrax must have looked more like a small hippopotamus than a hyrax. The snout was short, and a pair of very large incisor teeth projected downwards. The 2 pairs of lower in, cisors were flattened and horizontal, the upper pair fitting between their points when the jaw was closed.
	Classification:GENUS	Name:Labidosaurus	Age:Early Permian
	Locality:North America (Texas)	Size:2 ft 5 in/75 cm long	Fossil Name:
	Notes:This primitive, heavily built reptile was a squat animal with a large head and short tail. Its shape suggests that it was fully at home on land. A typical captorhinid, Labidosaurus had several rows of teeth in the jaws, all functional at the same time. This was an improvement on its ancestors, the protorothyridids, which had only a single row of small conical teeth in their jaws. The rows in Labidosaurus' mouth provided a broad surface on which shelled invertebrates, such as insects and snails, could be crushed, or tough plant material ground down.
	Classification:GENUS	Name:Lagosuchus	Age:Middle Triassic
	Locality:South America (Argentina)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Members of the family Lagosuchidae are the most dinosaurlike of all the thecodontians known. Lagosuchus itself is considered as the most likely ancestor of the dinosaurs. This is based mainly on the structure of its hip bones, ankle joints and long, slim hindlegs, in which the shin bones are almost twice the length of the thigh bones - a feature of running animals, and particularly well seen in the bipedal dinosaurs. In addition, Lagosuchus has been cite as a possible ancestor of the pterosaurs the flying reptiles which also appeared in Late Triassic times (see pp. 102-105).
	Classification:GENUS	Name:Lambeosaurus	Age:Late Cretaceous
	Locality:North America (Baja California, Montana and Saskatchewan)	Size:30ft/9m long	Fossil Name:
	Notes:This lambeosaur duckbill was unusual in having 2 distinct structures on its head. A tall, rectangular, hollow crest grew upward from the front of the head and pointed forward, while a solid, bony spike grew from the crown of the head and pointed backward. This V-shaped arrangement must have looked quite ungainly, mounted as it was on the long, flexible neck. Like all members of the duckbill family, Lambeosaurus moved about on all-fours while browsing on vegetation. Its flexible neck seems to have been an adaptation to allow the animal to reach around its body and gather low-growing plants from a wide area, without having to shift its position. The Californian specimen of Lambeosaurus seems to have been a giant among cluckbills. The remains are fragmentary, but the size and weight of the bones found indicate that their owner may well have reached a length of 54ft/16.5m, making it the largest hadrosaur known.
	Classification:GENUS	Name:Lariosaurus	Age:Middle Triassic
	Locality:Europe (Spain)	Size:2 ft/60 cm long	Fossil Name:
	Notes:Lariosaurus was one of the smaller nothosaurs, though not the smallest some of them were only 8 in/ 20 cm long. It possessed a number of primitive fea- tures, including a short neck and short toes. The webs of skin between the toes would therefore have been small in area, and not much use for swimming. This reptile probably spent much of its time walking about on the seashore or paddling around in the coastal shallows, feeding on small fishes and shrimps.
	Classification:GENUS	Name:Lepidotes	Age:Late Triassic to Early Cretaceous
	Locality:Worldwide	Size:1 ft/30 cm long	Fossil Name:
	Notes:Toward the end of the Paleozoic Era, many new types of ray-finned fishes evolved from the marine palaeoniscids. Grouped together as the neopterygians, these fishes show many of the features developed in the modern bony fishes, which descended from this group. Lepidotes (a member of the semionotids, see pp. 18-19) had evolved a new jaw mechanism, which allowed it to feed differently from earlier fishes. Its upper jaw bones were shortened and freed of their connection to the cheek bones, to which they had formerly been fused. This new mobility allowed the mouth to be formed into a tube, and prey could be sucked from a distance toward the fish, rather than engulfed at close quarters as early fishes had done.
	Classification:GENUS	Name:Leptictidium	Age: Middle Eocene
	Locality:Europe (Germany)	Size:2 ft 6 in/75 cm long	Fossil Name:
	Notes:Leptictidiurn probably resembled the modern elephant shrew, except for its longer hind legs and tail. It was a bipedal runner, like humans and some of the smaller flesh-eating dinosaurs. The hind legs were long, light and birdlike, with most of the muscles concentrated around the thigh. The forelimbs were less than half the length of the hindlimbs and were adapted for holding food. The body was very short and the long tail served as a balancing organ. Leptictidium ate more than just insects: some good skeletons show the remains of small mammal bones, lizard bones and plant matter, as well as fragments of insect shells.
	Classification:GENUS	Name:Leptoceratops	Age:Late Cretaceous
	Locality:North America (Alberta and Wyoming) and Asia (Mongolia)	Size:7 ft/2.1 m long	Fossil Name:
	Notes:This is one of the few protoceratopids known from North America; most of the family lived in Asia. In appearance, it was intermediate between the lightly built parrot dinosaurs and the heavier, early horned dinosaurs. It could probably walk on 2 legs as easily as on 4. Its hindlegs were built for running, as shown by the long shin bones, and the 5 clawed fingers of each hand could be used to grasp bundles of leaves, and pass them to the mouth. The bones at the back of Leptoceratops' skull were expanded upward into a tall peak. This was an intermediate stage in development between the muscle-attachment ridge of the parrot dinosaurs and the neck frill of the horned dinosaurs.
	Classification:GENUS	Name:Leptolepis	Age:Middle Triassic to Early
	Locality:Africa (Tanzania), Australia (New South Wales), Europe (Austria, England, France and Germany) and North America (Nevada)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Leptolepis and its relatives were herringtype fishes, like the pholiclophorids (above). But unlike them, the leptolepids lived and moved in shoals, gaining safety in numbers as they fed on plankton in the surface waters. This gregarious lifestyle is deduced from the many fossil finds in which hundreds of these fishes have been preserved in the same slab of rock. The leptolepids were also more advanced than the pholidophorids in 2 important respects. First, their skeletons were made entirely of bone, and second, their bodies were covered in thin, rounded scales with no enamel coat. Both these developments aided swimming. The backbone formed a strong, yet flexible, rod to resist the pressures created by the S-shaped bending of the body during swimming. The thin scales reduced the fish's weight, and their rounded shape made the body more hydrodynamic.
	Classification:GENUS	Name:Leptolepis	Age: Middle Triassic to Early Cretaceous
	Locality: Africa (Tanzania), Australia (New South Wales), Europe (Austria, England, France and Germany) and North America (Nevada)	Size:1 ft/30 cm long	Fossil Name:
	Notes:Leptolepis and its relatives were herringtype fishes, like the pholiclophorids (above). But unlike them, the leptolepids lived and moved in shoals, gaining safety in numbers as they fed on plankton in the surface waters. This gregarious lifestyle is deduced from the many fossil finds in which hundreds of these fishes have been preserved in the same slab of rock. The leptolepids were also more advanced than the pholidophorids in 2 important respects. First, their skeletons were made entirely of bone, and second, their bodies were covered in thin, rounded scales with no enamel coat. Both these developments aided swimming. The backbone formed a strong, yet flexible, rod to resist the pressures created by the S-shaped bending of the body during swimming. The thin scales reduced the fish's weight, and their rounded shape made the body more hydrodynamic.
	Classification:GENUS	Name:Lesothosaurus	Age:Early Jurassic
	Locality:Africa (Lesotho)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:This small animal was lightly built and fleet of foot, well able to sprint over the hot, dry plains of its home in southern Africa. Its long legs, short arms, flexible neck and slender tail were to set the general pattern which all subsequent ornithopods were to follow. Lesothosaurus' skull was small, short and flat-faced, rather like that of a modern iguana. The pointed teeth were shaped like little arrowheads, with grooved edges; when the animal was chewing, its upper teeth fitted alternately between the lower ones, to produce a chopping motion which would have dealt with tough plant food. A pair of Lesothosaurus skeletons were found preserved together in the rocks of southern Africa. Their bodies were curled up, and surrounded by worn, discarded teeth, although the skulls of both animals contained a full set of teeth. On the basis of this find, some paleontologists think that these little dinosaurs may have slept away the hottest, driest months of the year underground, as do many modern desert creatures. The worn teeth scattered around the bodies could have been shed during sleep, while new ones grew. Another find in Lesotho consisted of a jaw bone and some teeth. These scanty remains were called Fabrosaurus. It is possible that this animal and Lesothosaurus were the same creature.
	Classification:GENUS	Name:Limnofregata axygosternurn	Age:Early Eocene
	Locality:North America (Wyoming)	Size:up to 1 ft/30 cm tall	Fossil Name:
	Notes:Limnofregata azygosternurn appears to have been an ancestral form of the modern frigatebirds. Today, these are specialized marine birds, related to pelicans, and almost wholly adapted to an aerial existence over the sea. But 50 million years ago, they were only just evolving, and Limnofregata may be a halfway stage in their development. Limnofregata's general structure was similar, though less extreme, to that of modern frigatebirds. Its legs and feet, although reduced in size, were larger and longer than those of modern species. Its wings, too, were proportionally shorter, with a span of about 3 ft 3 in/ I In (compared with the long wings of the modern frigatebirds, up to 8 ft/2.5 m span in the largest species). Its bill was shorter, more tapering and less hooked than that of living species. However, unlike the modern frigate, birds, Limnofregata azygosternum did not glide on thermals over the ocean - it flew by flapping its wings, and its habitat was large, freshwater lakes, far inland. It was probably more like a gull in appearance and feeding method, and more likely to land on water than its modern relatives, which snatch up fish and squid without alighting on the water surface.
	Classification:GENUS	Name:Liopleurodon	Age:Late Jurassic
	Locality:Europe (England, France, Germany and USSR)	Size:39 ft/12 m long	Fossil Name:
	Notes:This large phosaur was typical of the later members of the family. It was whalelike in appearance, with a heavy head, short, thick neck and a streamlined body. From the structure of the limb girdles, it is evident that this plio, saur was extremely maneuverable in the water, and could swim at all depths. The front flippers were used in an upand-down motion, like those of the plesiosaurs. The strong downward stroke would have pushed water to the rear, so propelling the animal forward. On the recovery stroke, the flippers would have been lifted up automatically by the passage of water over their hydrodynamic shape. The hind flippers would have thrust back against the water in a powerful kicking motion, and then been turned, to offer the least resistance to the water on the recovery stroke. This combination of movements would have made for efficient, fast long-distance swimming. This, in turn, enabled the pliosaur to sustain the chase after its fast-moving cephalopod prey.
	Classification:GENUS	Name:Longisquama	Age:Early Triassic
	Locality:Asia (Turkestan)	Size:6 in/15 cm long	Fossil Name:
	Notes:A curious, lizardlike creature, Longiaquama was a tiny thecodontian. It cannot be placed in any of the known suborders or families of the group its body was covered in overlapping, keeled scales. A remarkable row of tall scales, stiff and V-shaped in crosssection, rose from the back. Their function is unknown. They could have been display structures, either for attracting a mate or for warning away rivals. Other suggestions are that they could have been used for gliding through the air, or as heat-exchange devices; they may even have been an early stage in the evolution of feathers.
	Classification:GENUS	Name:Lycaenops	Age:Late Permian
	Locality:Africa (South Africa)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes:Lycaenops, or "wolf face," was a small, lightly built carnivore, with long running legs. It was a member of the gorgonopsians, the dominant predators of the Late Permian in southern Africa and European Russia. It may have hunted in packs, and probably preyed on large, plant-eating therapsids, such as Moschops. The canines were particularly long, and the front part of the skull was deeper than normal to accommodate their roots.
	Classification:GENUS	Name:Lystrosaurus	Age:Early Triassic
	Locality:Africa (South Africa), Antarctica, Asia (China and India) and Europe (USSR)	Size:3 ft 3 in/1 m long	Fossil Name:
	Notes: The remains of Lystrosaurus were found in Antarctica in the late 1960s. The wide distribution of this sturdy, herbivorous dicynodont provides further evidence that, during Late Permian and Triassic times, India and all the southern continents were united as one landmass, Gondwanaland. Lystrosaurus was a kind of reptilian "hippopotamus." It probably wallowed in the shallows, browsing on water weeds uprooted with its single pair of tusks. Its nostrils were placed far back on the skull, near the eyes, where they would clear the water while the rest of the body remained submerged.
	Classification:GENUS	Name:Macrauchenia	Age:Pleistocene
	Locality: South America (Argentina)	Size:10 ft/3 m long	Fossil Name:
	Notes:Macrauchenia was a later and larger version of Thesodon, from which it may have evolved. The lifestyle of Macrauchenia ("large neck") is an enigma. As its name implies, it had certain camel-like features - including size, posture, small head and long neck. But its 3-toed, hoofed feet were rhinoceroslike, and it probably bore a substantial trunk, too, since the nostrils enter the skull high up between the eyes. Some paleontologists have suggested that signs of a trunk imply a semi, aquatic lifestyle. Others regard it as evidence that the nostrils were simply surrounded by lips which could be closed to keep dust out. The presence of a trunk allied to high-crowned cheek teeth also suggests that Macrauchenia may have been able both to browse and to graze. The legs were long, and the front legs were much longer below the knee than above it-a common feature of run, ning animals. However, Macrauchenia would probably not have been able to run fast since the proportions of the hind limbs were reversed, as in nonrunning animals.