Family Miacidae
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 car 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...
Order Lipotyphla
The Lipotyphla includes 5 fossil and 7 living families. The latter include hedgehogs, shrews and moles, as well as sole-nodons of the West Indies, golden moles of Africa, tenrecs of Madagascar and otter shrews of Central Africa. name Palaeoryctes time Early Paleocene to Early Eocene A well-preserved skull shows Palaeoryctes must have closely resembled a modern shrew in appearance, with a small sleek body and a pointed snout armed with little insect-crushing teeth. Although it ate mostly...
Diadecte 1
as a larva. This phenomenon is called paedomorphosis, and is seen in several modern salamanders, such as the cave-dwelling olm of Europe and the North American mudpuppy. The Mexican axolotl goes one step further it also retains the tadpole tail of its youth. name Pantylus time Early Permian locality North America Texas size 10 in 25 cm long A great head on a small, scaly body characterized this microsaur. It was a well-adapted land animal, moving about on short, sturdy limbs. It probably lived...
time Late Jurassic 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 Dryosaurus also known as Dysalo-tosaurus 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...
name Ursus spelaeus time Pleistocene to Recent locality Europe Austria
Germany, Netherlands, Spain, UK and USSR size 6 ft 6 in 2 m long The genus Ursus is represented today by the brown, or grizzly, bear, the polar bear and the American black bear. But in Pleistocene times, the cave bear, Ursus spelaeus, was a particularly numerous and impressive species. It lived in Europe during the height of the Ice Age, and often escaped the worst of the winters by hibernating in Alpine caves. Many bears seem to have congregated together for this long, annual sleep, to judge...
Wyoming Asia China and
Europe France size 5 ft 1.5 m long Hyrachyus was generally very similar to Heptodon see pp. 258-261 , but a little larger and more heavily built. It was a common 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 rhinoceroses. 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.
Order Dermoptera
The dermopterans constitute the group of flying lemurs a confusing name since they are neither lemurs, nor do they fly. Only 2 species survive today the colugos Cynocepkalus of Southeast Asia, both strict vegetarians. These modern animals, less than 1 ft 30 cm long, can glide as far as 450 ft 137 m from tree to tree on outstretched skin membranes. It is assumed, though there is no direct evidence for this, that Mid-Paleocene and Early Eocene dermopterans could do likewise. There is some...
Family Viverridae
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 Paleocene, 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...
Introduction
The solar system, which includes the Earth, is about 4-6 billion years old. The earliest traces of life on our planet are microscopic fossils of blue-green algae and bacteria that are found in rocks some 3.5 billion years old opposite . The atmosphere of the ancient Earth contained no oxygen. Like most modern green plants, the early algae produced oxygen, but this would have quickly disappeared because it combined readily with various elements and compounds in the Earth's crust. Not until about...
Suborder Cryptodira
The cryptodires were the most successful group of chelonians, and survive to this day most modern turtles and tortoises belong to this group. Many of them can retract their heads into the shell by lowering the neck and pulling it back vertically. As a group, the cryptodires evolved along with their pleurodire cousins during Jurassic times. But by the end of that period they had become enormously diverse, and replaced the pleurodires in the seas, rivers and lakes of the world. New forms...
Family Tapiridae
The family to which the modern tapirs belong, the Tapiridae, 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 southern supercontinent of Gondwanaland. It is...
Order Actinistia
The actinistians, or coelacanths, have a long evolutionary history, longer in fact than anyone thought. They arose in the Middle Devonian and the last fossils found come from Late Cretaceous rocks, some 70 million years old. Then, in 1938, a living coelacanth was caught in the deep waters of the trench that separates Madagascar from southern Africa. The people of the nearby Comoro Islands had known of this fish for generations, but it was new to science. The term living fossil was awarded to...
locality Africa Namibia Asia
China and Europe France size 6 ft 6 in 2 m long 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 above . 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. name...
name Scarrittia time Early Oligocene locality South America
Argentina size 6 ft 2 in 2 m long Scarrittia is the only member of the Leontiniidae that we know from a well-preserved skeleton. In life, it probably looked much like a lumbering, flat-footed rhinoceros. Scarrittia was a rather heavy animal with a long body and neck, stout legs, 3-toed hoofed feet, and a very short tail. The tibia and fibula were partly fused at the top, so the feet could not be turned sideways. The face was quite short and the jaws contained the full complement of 44...
name Thesodon time Early Miocene locality South America
Argentina size 6 ft 6 in 2 m long Trotting across the Pampas plains, this browsing and grazing long-necked creature would have looked much like a modern guanaco. The main difference would have been in the feet, which in Thesodon were 3-toed and hence rather heavier. The position of the nostrils in the skull suggests that a trunk was also present, but this may have been no more prominent than the one carried by the living saiga antelope. The lower jaw was very slim and the mouth had a full set...
Order Therapsida
The therapsids were advanced synapsid reptiles, and the direct ancestors of the mammals. Although the remains of the first therapsids are found at the base of the Late Permian, they had diverged from the sphenacodont pelycosaurs more than 20 million years before, probably during the Early Permian. They spread rapidly to all parts of the world, including Antarctica. The therapsids are grouped into several suborders see pp. 58-59 , only one of which, the cynodonts, survived into the Jurassic see...
Family Elephantidae
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...
Order Sirenia
The sirenians, or sea cows, are the only group of mammals to have become fully adapted, aquatic herbivores. Today, they are represented by 3 species of manatee Trichechus and a single species of dugong Dugong dugon . They all have bulbous bodies, forelimbs modified into flippers, no hindlimbs and a horizontally flattened tail, like that of a whale, which they use to propel themselves through the water at a leisurely pace. Sirenians are known from the Early Eocene of Hungary. Their evolution is...
Subclass Lepospondyli
Contemporary with the large, bulky labyrinthodonts see pp. 50-53 were a group of smaller, insectivorous amphibians, grouped together as the lepospondyls. The anatomical feature that unites them is the structure of their vertebrae. These amphibians evolved in the Carboniferous period, and survived until the end of the Permian. During this span of some 100 million years, a variety of small lepospondyls evolved, which tended to look like salamanders or snakes. They can be grouped into 3 major...
Family Myrmecophagidae
The myrmecophagids, or true ant-eaters to distinguish them from the completely unrelated marsupial ant-eaters such as the modern numbat Myr-mecobius are highly specialized for exploiting a diet of ants and termites. Their evolution is little known an early form, Protamandua, from the Early Miocene about 20 million years ago, was already a typical anteater. name Eurotamandua time Middle Eocene locality Europe Germany size 3 ft 90 cm long Until recently, when a fossil anteater was discovered in...
Protorothyrididae
Members of this family are the earliest-known reptiles. They first appeared in the Late Carboniferous period, and survived into Mid-Permian times, a span of some 50 million years. The protorothy-ridids were the basal stock from which many specialized groups evolved, including the ruling reptiles the dinosaurs, crocodiles and flying pterosaurs see pp. 90-93 . name Hylonomus time Late Carboniferous locality North America Nova Scotia size 8 in 20 cm long Hylonomus is the earliest-known,...
Family Enaliarctidae
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 above , 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 below . Later still, about 15 million years ago, some of the enaliarctids evolved into...
Family Mosasauridae
The mosasaurs were a successful, though short-lived, offshoot from the monitor lizard group. They were fully adapted to a marine life, living in inshore waters during the Late Cretaceous period. Some of them were giants. name Platecarpus time Late Cretaceous locality Europe Belgium and North America Alabama, Colorado, Kansas and Mississippi size 14 ft 4.3 m long Many specimens of this marine lizard have been found in the chalk deposits of Kansas, laid down in the warm, shallow seas that covered...
locality Australia New Zealand
and South America size 7 ft 5 in 2.3 m long Prosqualodon and its immediate family may have been ancestral to all the other toothed whales. It probably looked like a small modern dolphin, with a long, narrow snout armed with pointed, fish-catching teeth. But the teeth were primitive, since there were still triangular teeth at the back of the jaws, as there had been in the earlier whales, the archaeocetes above . Prosqualodon's skull had become lightweight as a result of several modifications to...
locality South America
Argentina size up to 33 ft 10 m long The limb bones, and the shoulder and hip girdles of this large prosauropod, were much more massive than those of its relatives, the plateosaurs above . This indicates that it was an obligatory quadruped that is, it had to walk on 4 legs in order to support its great weight. The skeleton was modified accordingly. The limb bones were thick and solid, and held vertically beneath the body. The hips were fused to the backbone by 3 vertebrae, giving a solid...
North America Nebraska size ft m high
This 4-tusked mastodont was wide-ranging, 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...
Seymouria 1
Cacops was a member of the dissoro-phids. This diverse family of temno-spondyls 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 arid conditions of the Permian. Cacops and its relatives, along with some of the eryopids, were quick...
Hypsilophodontidae
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...
Order Nectridea
The nectrideans were 4-legged amphibians, newtlike in appearance and with long, flattened tails for swimming. Exclusively aquatic in lifestyle, they evolved during the Late Carboniferous, and survived until the end of the Permian. Early nectrideans had a skull structure very like that of a labyrinthodont. Their limbs were well developed, with 5 toes on each. The later members of the group tended to have small forelimbs, and a toe had been lost from each. The snout also became greatly elongated...
Family Millerettidae
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...
Infraorder Coelurosauria
Traditionally, the carnivorous thero-pods are further subdivided into infra-orders according to their size. There were large, massively built predators called carnosaurs see pp. 114-121 . There were medium-sized carnivores called deinonychosaurs, with a killing claw on each hind foot see pp.110-113 . And there were small, lightweight hunters called coelurosaurs below . Their name means hollow-tailed lizards, and refers to the thin-walled, hollow bones that made up not only their tails, but most...
Family Trionychidae
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 Meiolaniidae
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. locality Australia Queensland, New Caledonia and Lord Howe Island size 8 ft 2.5 m long Apart from its great size, the most remarkable feature of this well-armored tortoise was the flamboyant ornamentation on its head. It was...
Suborder Hegetotheria
Like the typotheres above , in whose suborder they are often placed, the hegetotheres include rabbitlike and rodentlike forms which became effective gnawers. Later representatives have a diastema between incisors and cheek teeth, and all teeth grew throughout life. They emerged slightly later than the interatheriids, during the Middle Eocene, and did not become extinct until the Pliocene, about 3 million years .' .'
ORDER UNCERTAIN Hax
The claudiosaurs were marine reptiles that evolved in the Late Permian period. Their classification is uncertain, but they may represent a transition group between the land-living eosuchian reptiles seep. 85 and the later, more advanced aquatic reptiles, the nothosaurs and their relatives, the plesiosaurs. Only one genus of claudiosaur has been found to date a semi-aquatic, lizardlike animal named Claudiosaurus, which is placed in its own family, the Claudiosauridae below . name Claudiosaurus...
Pachycephalosauridae
The skulls of the so-called thickheaded lizards, or boneheads, 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 had a similar lifestyle to that of modern mountain goats. Like these mammals, they would have lived together...
South Dakota size ft m long
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 see p. 144 . But unlike the early, inaccurate reconstructions of...
Suborder Archaeoceti
The archaeocetes were the first cetaceans to appear, in the seas of the Early Eocene, about 54 million years ago. They evolved from amphibious mammals, and at first were small never more than 10 ft 3 m long , 4-legged, seallike creatures with few specializations for life in water. But by the end of the Eocene, some 15 million years later, they had developed into enormous, serpentlike animals, highly adapted for a marine life. name Pakicetus time Early Eocene locality Asia Pakistan size 6 ft 1.8...
Order Ciconiformes
This large order includes the modern shorebirds the wading water birds other than waterfowl, see p. 181 , the seabirds and the typical birds of prey. Most of them evolved and diverged to occupy different habitats toward the end of the Cretaceous period. Birds of prey, such, as the eagles, were widespread from the Eocene onward below . name Harpagornis moorei time Pleistocene to Recent locality New Zealand size possibly 3 ft 6 in 1.1 m tall This eagle may not have been much larger than many of...
Subclass Elasmobranchi
The elasmobranchs sharks, dogfishes, skates and rays evolved from a common ancestor during the Early Devonian, some 400 million years ago. Sharks have changed little over this vast span of time. They diversified into many forms during the Carboniferous, and after a period of decline, underwent a second burst of evolution in the Jurassic, when most of the modern groups appeared. Then, as now, sharks were the dominant predators in the seas, ousting other creatures that attempted a marine,...
Suborder Elephantoidea
This suborder contains 3 families 2 are families of browsing mastodonts Gom-photheriidae and Mammutidae and the other is the family which contains the mammoths and true elephants Elephantidae . Gomphotheres are the more primitive of the 2 families of mastodonts the term refers to the paired domed cusps which occur along the length of the teeth. They appeared in the Early Oligocene about 35 million years ago. In these early forms, both upper and lower jaws were quite long. More advanced forms,...
Subclass Neornthes
This group of new birds encompasses all recent species. They began to adapt to varied environments in the Early Cretaceous, and representatives of most of the modern groups had appeared by the Early Eocene, some 50 million years ago see pp. 170-171 . A number of extinct groups and species are known, of which the following are some of the more striking.
Oklahoma Utah and Wyoming size up to ft m long
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 tonnes 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 A patosaurus. Up until 1975, the skull of...
Armored dinosaurs 1
name Sauropelta time Early Cretaceous locality North America Montana size 25 ft 7.6 m long Sauropelta, from the western USA, is the largest known member of the nodosaur family of ankylosaurs, the armored dinosaurs of Cretaceous times. It is estimated to have weighed over 3 US tons 3 tonnes. Its massive body was encased in a bony armor. This consisted of bands of horn-covered plates with raised keels, which ran transversely over the body from the neck to the end of the long, tapering tail. The...
Protobrama 1
time Late Jurassic to Late Cretaceous locality Europe England, France Thrissops was a streamlined predator that hunted others of its own kind in the warm, shallow seas of the Late Mesozoic, some 140 million years ago. Its tail was deeply cleft into 2 equal lobes, which may have increased its speed. The pelvic fins were tiny, and could have played little part in stabilizing the fish's deep body in the water. Perhaps to compensate for this, the anal fin formed a long fringe on the underside....
name Megantereon time Late Miocene to Early
Pleistocene locality Africa South Africa , Asia India , Europe France and North America Texas size 4 ft 1.2 m long Megantereon was an early true sabertooth cat, and it was probably ancestral to other forms. Its teeth were not quite long enough to be really saberlike they were more like daggers in size and shape, so Megantereon and its immediate relatives are often known as the dirktooth cats from the Scottish word for dagger, dirk . The development of long canines enabled these powerful...
Order Uncertain
The remains of about 5 genera of Carboniferous amphibian have been found in Europe and North America. Although they can be grouped into families, they do not fit into any of the known orders. name Crassigyrinus time Early Carboniferous locality Europe Scotland size 6 ft 6 in 2 m long Crassigyrinus was a strange-looking creature, even for an early amphibian. It had a fishlike body tapering into a long tail, with tiny finlike limbs. Its head was about 1 ft 30 cm long, and the teeth-filled jaws...
Suborder Cynodontia
The cynodonts, or dog teeth, were the most successful group of therapsid reptiles. Not only were they the longest-lived group, surviving for some 80 million years, from Late Permian times to about the middle of the Jurassic. They were also the direct ancestors of the world's most successful modern group of animals the mammals. The first fossil cynodonts are found in the Late Permian rocks of European Russia and southern Africa. They show many advanced mammalian characteristics. For example,...
Family Mesosauridae
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. America Brazil size up to 3 ft 3 in 1 m long This small creature was the first reptile to revert to a water-dwelling existence. It possessed many adaptations to an aquatic life. Its long tail was flattened from side to side, and...
Paracyclotosaurus
Permian locality North America New Mexico, Oklahoma and Texas size 6 ft 6 in 2 m long 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...