Lambeosaurines

Large bony head crests were a dinstinctive feature of these hadrosaurs. Powerful limbs supported a heavy body, and the downward-curving lower jaw had a broad, blunt beak. They lived around the same time as the hadrosaurines, and their remains have been found in North America and Asia. Hypacrosaurus The head crest of Hypacrosaurus was made of bones that grew up from the nose. Hadrosaurs probably used their hollow crests to amplify the sound of their calls, although the crests may also have...

More sauropods

Sauropod Anatomy

Short skull The short and high skull of Camarasaurus has a very large orbit eye socket and naris nostril socket . There are approximately 48 spoonlike teeth. , Toothless snout tugged leaves from trees Scientists used to think that the ankylosaurs were the only armored dinosaurs. But the discovery of Saltasaurus proved that some sauropods had armor, too. It was also thought that sauropods may have lived in water, but we now know that the high water pressure at depth would not have allowed them...

Warm and cold blood

Reptiles are cold-blooded, which means that they depend on conditions outside their body, such as the Sun's heat, for temperature control. Warm-blooded animals, such as mammals, produce heat from food energy, have hair for warmth, and sweat to cool down. Although dinosaurs were reptiles, much of their behavior, such as agile running, has more in common with Blood and bones Dinosaurs had bones more like mammals than reptiles. Mammal bones contain mammals. scientists are therefore puzzled over...

Ceratopsians

Dinosaurs Anatomy Triceratops

Horns, bony frills, and a parrotlike beak were the trademarks of the ceratopsians. They were all quadrupedal herbivores, and many ceratopsians lived in great herds. Most ceratopsians can be divided into two groups. One group had short neck frills, the other had long neck frills. The ceratopsians were among the last dinosaurs to become extinct. Psittacosaurus This dinosaur was a 61 2-ft-long 2 m bipedal ancestor of the ceratopsians. It had a parrotlike beak and a very small neck frill, but...

Dinosaurs

Dinosaurs Anatomy Triceratops

With additional material from Dougal Dixon LONDON, NEW YORK, MUNICH, MELBOURNE AND DELHI Production Nicola Torode With thanks to the original team Art editors Ann Cannings Sheilagh Noble Picture research Caroline Brooke Published in the United States by DK Publishing, Inc., 375 Hudson Street, New York, NY 10014 This edition copyright 2002 Dorling Kindersley Limited Pockets Dinosaur copyright 1995 Dorling Kindersley Ltd Some of the material in this book originally appeared in Pockets Dinosaur,...

Early start

Maiasaura Nesting Site

Unlike the Maiasaura young, who were looked after by their mother for several weeks, Orodromeus young left their nests as soon they hatched from their eggs. The young Orodromeus would have been preyed upon by carnivorous dinosaurs, such as sharp-sighted Troodon. Newly hatched Orodromeus leaving nest Newly hatched Orodromeus leaving nest

Discovering dinosaurs

Everything we know about dinosaurs is based on their fossilized remains. These are pieced together to make the skeletons we see in museums. Sir Richard Owen, the famous dinosaur expert, first named some reptile fossils as dinosaurs in 1841. Fossils are the remains of ancient living things buried and preserved in rocks. Most fossils were formed from tough body parts, such as the bones of animals or the woody parts of plants. Fossilization is a very slow process - it usually takes millions of...

About saurischians

There were two main groups of saurischians -the theropods and the sauropodomorphs. The largest dinosaurs, and some of the smallest, were saurischians. This group differed from ornithischians mainly because of the shape of the hipbones. Sharp-toothed jaws typical of the meat-eating theropods Sharp-toothed jaws typical of the meat-eating theropods Sauropodomorphs Members of the sauropodomorph group were mainly herbivorous and quadrupedal walked on four legs . The sauropodomorphs included the...

Reptiles in the air

The pterosaurs were the first ever flying vertebrates animals with a backbone . Their wings were a thin membrane of muscles and elastic fibers covered with skin. The rhamphorhynchoid group of pterosaurs had long tails and short heads with sharp teeth. They first appeared in the Triassic period and became extinct at the end of the Jurassic period. Rhamphorhynchus Rhamphorhynchus, a rhamphorhynchoid, had a special beak for trawling the water surface to catch fish while flying. The jaws were armed...

Volcano theory

Extinct Skelton Diagram

Many volcanoes were active during the Cretaceous period. There were vast lava flows in the area that is now India. This would have poured huge amounts of carbon dioxide into the air, causing overheating, acid rain, and the destruction of the protective ozone layer. Megazostrodon was a mammal that lived in the Triassic period. Flowers Flowering plants may have contributed to the extinction of the dinosaurs. Many of these plants would have been poisonous, and any herbivorous dinosaur that ate...

Prosauropods

Dinosaur Anatomy

The prosauropods are thought to be the ancestors of the sauropods. Both groups have long necks and small heads, but the prosauropods were generally smaller in size. Most prosauropods were herbivores, although some may have been omnivores eating both meat and plants . Thumb claw Massospondylus may have been an omnivore since it had large, serrated front teeth. It also had sharp thumb claws, which it may have used to attack prey, as well as for defense. Riojasaurus, at 33 ft 10 m in length, was...

Pachycephalosaurs

The thick, domed skulls of pachycephalosaurs earned them the name bone-headed dinosaurs. Rival males used to bash their heads together, their brains protected by the thick bone. Pachycephalosaurs probably had a good sense of smell, which would have allowed them to detect nearby predators and escape before the predators got too close. Horn cluster Stygimoloch had a cluster of horns behind its dome. But the horns were probably just for show, rather than of practical use. Lots of nodules...

More carnosaurs

Fossilized remains of carnosaurs have been found worldwide. Many of the carnosaur skeletons that have been found are very incomplete. Consequently, they are difficult to study and understand, since pictures of whole dinosaurs have to be built up from small fragments of evidence. Scientists cannot even be sure that all of the dinosaurs they have grouped in the carnosaur group are, in fact, carnosaurs. Found only in Argentina, Carnotaurus was about 40 ft 12 m long. Its short, stubby head had the...

More reptiles at sea

Plesiosaurs, pliosaurs, and turtles probably hauled themselves onto beaches to lay eggs, the way modern turtles do. Ichthyosaurs did not leave the water since they were fully adapted to life at sea and gave birth to live young. By the time the dinosaurs died out, all sea reptiles, apart from the turtles, had become extinct, too. The reason for this is as mysterious as the disappearance of Fossil shell of the 12-in-long 30 cm turtle Cimochelys Fossil shell of the 12-in-long 30 cm turtle...

What are dinosaurs

Anatomy Dinosaurs

About 225 million years ago, a new group of reptiles appeared on Earth. Like all reptiles, they had waterproof, scaly skin and young that hatched from eggs. These were the dinosaurs. For the next 160 million years they ruled the Earth, before finally becoming extinct Dinosaurs were land animals -they could not swim or fly. All dinosaurs had four limbs, but many, such as Tyrannosaurus rex, walked on only their two back legs, leaving the front legs free for other tasks. Powerful neck muscles were...

Cretaceous world

Cockroah Dinosaur Era

In the Cretaceous period, North America, Europe, and Asia were part of a much larger continent called Laurasia. Herbivorous dinosaurs, which included the ceratopsians and the hadrosaurids, browsed among marshy lowlands. The giant sauropods became rare. In the late Cretaceous the terrifying tyrannosaurids appeared. They were the top predators until the extinction of the dinosaurs, at the end of this period. Dinosaur life Small herbivores were more common in this period. Carnivores like Baryonyx...

Fleet foot

The Claw Part Hoof

Ornithomimus was one of the speediest dinosaurs. its three foot bones were locked together, making a long extension to the leg. Running on the tips of its toes, it could take long strides. Ornithomimus may have reached top speeds of 37 mph 60 km h - fast enough to escape most predators. Legs like pillars The heaviest dinosaurs had pillarlike legs, like those of elephants. Brachiosaurus weighed about 50 tons tonnes so it needed thick, strong legs to support its body. Widely spaced toes and...

The first dinosaurs

Several groups of reptiles existed before the dinosaurs appeared. One group was the thecodonts. These were the ancestors of the dinosaurs, and they probably also gave rise to the pterosaurs and the crocodiles. Thecodonts were large carnivores that had straighter legs than other reptiles. The first dinosaurs were also carnivores, and the earliest known dinosaur, Eoraptor, first appeared 228 million years ago. tiH r r 1 r a very early dinosaur Eoraptor may have been the first dinosaur. It was...

Triassic world

The Triassic period was the beginning of the Mesozoic era, which lasted until the end of the Cretaceous period. The first dinosaurs appeared in the Triassic period. These dinosaurs were agile carnivores that evolved rapidly. Some became herbivores. Small mammals also appeared at this time, as did the flying reptiles, called pterosaurs. The pterosaurs were cousins of the dinosaurs, and were the only reptiles ever to fly. They flew above the conifer forests catching insects. They may also have...

About sea and air reptiles

Pterodactylus

While the dinosaurs lived on land, other reptiles lived in the sea and flew in the air. The sea reptiles, such as the ichthyosaurs and plesiosaurs, needed to breathe air and would have surfaced frequently to fill their lungs. The flying reptiles, called pterosaurs, included the largest ever flying animals. There were two grouPs of pterosaur - rhamphorhynchoids and pterodactyloids. Pterodactylus was a small pterosaur with a wingspan of only 20 in 50 cm . Pterodactylus was a small pterosaur with...

Stegosaurs

Dinosaur Skeleton Ground

The most noticeable features of the stegosaurs were the large plates, or spines, along an arched back. These plates may have regulated body temperature, and they may have also given protection, or even attracted a mate. Stegosaurs had small heads, and tiny brains no larger than a golf ball. The head was carried close to the ground for eating short, leafy plants and fruits. Tail end commonly known of all stegosaurs. It had long, horny spines on the end of its tail. With a quick swing of the...

Carnosaurs

Allosaurus Skeletons And Bones

Of all the theropods, the ferocious carnosaurs are probably the most famous. Some carnosaurs could run as fast as 22 mph 35 km h on their large and powerful back legs. Massive heads carried a fearsome array of enormous serrated and curved teeth. Tyrannosaurus rex was the largest of the carnosaurs, and the most successful predator in the Cretaceous period. During the Jurassic, Allosaurus was the top predator. Like all carnosaurs, Allosaurus walked on three large, clawed toes. The feet were...

Shortfrilled ceratopsians

The group of ceratopsians with short frills also had long nose horns and short brow horns. Styracosaurus had the most dramatic frill, with long horns growing out from its edge. The discovery of five young near an adult Brachyceratops indicates that these ceratopsians looked after their young. It is likely that when a herd was in danger from predators, the males protected the young and the females. Six long spikes edged the frill of Styracosaurus. It had a lethal horn on its nose that was 2 ft...

More types of dinosaur

Types Dinosaurs

We will never know how many different kinds of dinosaur existed over the 160 million years of their existence. We do know that some fossil remains belong not to the dinosaurs but to swimming and flying relatives. Iguanodon was about 29V2 ft 9 m long. 1 Iguanodon was about 29V2 ft 9 m long. 1 Very common Iguanodon was a common dinosaur. In one location, between 1878-81, coal miners in Belgium dug up more than 39 Iguanodon skeletons. very rare Baryonyx is one of the rarest dinosaurs known. Only...

Herbivores

Herbavores The See Teeth

Plant-eating dinosaurs had to eat large amounts of plants every day to fuel their bodies. An herbivore's special diet needed special ways of eating and digesting food. Some herbivores' teeth were shaped for chopping, raking, or crushing. Other herbivores had sharp beaks for snipping leaves and twigs. Once swallowed, these tough plants may have taken days to digest. Grinding gut Barosaurus did not chew its food -it swallowed tough leaves and twigs whole. In a part of its stomach, stones called...

Time lines

Species Dinosaurs

Dinosaurs lived through three periods in the Earth's history - Triassic, Jurassic, and Cretaceous. Different species of dinosaur lived and died throughout these three periods. Each species may have survived for only Dinosaur designs were varied and spectacular. A group of dinosaurs called the sauropods were the largest land animals that ever lived. The smallest dinosaurs were dog-sized. Large or small, all would have been wary of hungry meat eaters. Some dinosaurs had armored skin for...

Lifestyle facts

Dinosaur Anatomy

Some dinosaurs may have lived for 200 years. Tyrannosaurus rex is the largest land-living carnivore we know of. The largest dinosaur eggs probably belonged to the sauropod Hypselosaurus. Dinosaur embryos have been found fossilized in their eggs. Fast food Dromaeosaurus had features common to many carnivores. It was fast, agile, and armed with sharp teeth and claws. Dromaeosaurus may have hunted in packs, chasing and bringing down , much larger animals. From the side, Baryonyx's skull appears...

Ankylosaurids

Horny Bony

Many ankylosaurids had spines on their sides as well as bony body scutes plates . Their most notable feature was a heavy tail club, which they used as a formidable weapon The triangular skull of Ankylosaurus was covered with bony plates. It ended at a horny beak, which it used to crop vegetation. Euoplocephalus Euplocephalus' head was armored with bony slabs. Its eyelids were bony too, protecting the vulnerable eyes. The stout body and tail club were typical of ankylosaurids. The bony plates...

Sauropods

Tail Weapon

The largest-ever land animals were included in the sauropod group. Sauropods were quadrupedal, plant-eating saurischian dinosaurs. They all had huge bodies with long necks and elephant-like legs. They also had long tails which they used as whiplike weapons against enemies. Tail reinforcement Tail bones like the one above were on the underside of Diplodocus' tail. They reinforced and protected the tail when it was pressed against the ground. Diplodocus had a long skull with peglike teeth at the...

Polacanthus Skin

Polacanthus Armor Fossilized Skin

Tail bones tightly locked together balancing act Scientists once believed that Parasaurolophus used its thick tail for swimming by sweeping it from side to side like a fish's tail. But they now think that the tail counterbalanced the front of the body. When defending itself, Diplodocus used its long tail like a huge whip to swipe at its attacker. The tail had 73 bones joined together, and made a powerful weapon with its The tail bones of Deinonychus were locked together by long bony rods,...

Dinosaur anatomy

Dinosaur Anatomy Pelvic Skin

The size and shape of a dinosaur's head, body, and legs help us to tell one dinosaur from another, and also tell us how the body parts were used. From the skeleton inside to the scaly skin outside, each part of a dinosaur helps build a picture of these amazing animals. The shoulder and pelvic muscles were crucial areas of power for light, fast runners as well as slow, heavy plodders. The largest dinosaurs were not always the mightiest. Some of the smallest dinosaurs were powerful runners....

Eggs nests and young

Dinosaurs laid eggs, like most other reptiles as well as birds. In recent years, scientists have discovered dinosaur nesting sites that gave them an insight into the early life of dinosaurs. These sites showed that some young stayed in their nests, cared for by adults, until they were old enough to leave. They also showed that dinosaurs, like many birds, used the same nesting sites year after year. Fossil egg with broken eggshell fragments Egg find The discovery of clutches of Proto-ceratops...

Reptiles at sea

Reptiles Sea

The sea reptiles evolved from land reptiles that adapted to life in the water. The legs and feet shortened and widened to become paddles, and the body became streamlined for faster movement through water. These reptiles were carnivores, preying on other sea creatures as well Modified paddle The plesiosaur Cryptoclidus was 13 ft 4 m long and had four paddles that were each about 3 ft 1 m long. it swam by flexing these powerful paddles up and down, flying through the water in the way that...

Hadrosaurines

Edmontosaurus Maiasaura

This group of hadrosaurs had little or no head crest, although some had a bump above the nose which they used for making Hadrosaur family noises. Some hadrosaurines had bills Maiasaura bred in huge that curled upward, forming a spoon rabmes, usmg the same shape. They lived in North America, nestings e year. The and Asia during the late name Maiasaura means good r mother lizard Maiasaura cared Cretace Us period. for their young until they could fend for themselves. Edmontosaurus had skin flaps...

Story of a dinosaur fossil

Pics Struthiomimus Fossils

IThe dinosaur Struthiomimus lies dead on a riverbank. For Struthiomimus to have a chance of fossilization, it must be buried quickly before it rots away. 2 Buried under many layers of sediment, over millions of years, the hard parts of Struthiomimus change to stony fossils. It is rare to find a perfectly preserved whole skeleton. It is rare to find a perfectly preserved whole skeleton. Uncovered fossil An almost perfect fossil of Struthiomimus, lying in its death pose, has been carefully...

Jurassic world

Dead Dinosaur River

Early in the Jurassic period, the herbivorous dinosaurs were mainly prosauropods and small ornithopods. By the late Jurassic, herds of giant sauropods roamed the land. These dinosaurs, as well as other reptiles and mammals, fed on the lush plant life. The first birds appeared, but the pterosaurs remained the rulers of the skies. Dead dinosaurs were eaten by other dinosaurs and scavenging crocodiles. River life Crocodiles hunted in the rivers, feeding on other river animals such as turtles,...

Dinosaur world

Cretaceous Period World Map

The world has not always looked the way it does today. Continents are constantly moving, and this very gradually changes the appearance of the Earth. The Triassic, Jurassic, and Cretaceous worlds all looked very different from one another. Mountains grew up erosion wore land away, and plants and animals, including the dinosaurs, appeared and disappeared. Two plates The Earth's lithosphere outer layer is made up of colliding forms massive plates, which move on the semimolten rock underneath....

Dinosaurs and birds

Skeleton Theropod Dinosaurs

Surprising though it might seem, scientists now recognize birds as the closest living relatives of dinosaurs. The most primitive bird is Archaeopteryx. In 1861, an Archaeopteryx skeleton together with fossil impressions of its feathers were found in a quarry in Germany. Archaeopteryx lived about 140 million years ago, alongside the dinosaurs that Lightwe ght Compsognathus fossil The fossil skeletons of Compsognathus above and Archaeopteryx look very similar. Scientists found an Archaeopteryx...

Brain casts

Sound Making Dinosaur

Tyrannosaurus rex's brain was bigger than Barosaurus'. Brains are too soft to fossilize, but casts from the inside of dinosaur skulls show us their shapes and sizes. Parasaurolophus and other crested dinosaurs could produce noisy signals from their head crests, identifying themselves to each other or warning of danger. Tubular sound chambers ran from the nose of Parasaurolophus up into its crest. Air traveled through this prehistoric trombone, where it vibrated as sound. View from left View...

Sauropodomorphs

Walking With Dinosaurs Brachiosaurus

Two groups, the prosauropods and the sauropods, are included in the sauropodomorphs. Unlike the theropods, most sauropodomorphs were quadrupedal walked on four legs and were herbivores. They had long necks and tails, and ranged in size from 6 2 ft 2 m to 130 ft 40 m in length. thumb claw Many sauropodomorphs had big, curved thumb claws. They probably used these dangerous weapons for defense. as Plateosaurus were the first large land animals. as Plateosaurus were the first large land animals....

Dromaeosaurids

Dromaeosaurid Anatomy

These razor-toothed carnivores were very agile and had large brains and huge eyes with stereoscopic vision. They were among the most terrifying of all dinosaurs. A large sickle-shaped talon on their inner toes could rotate through 180 , slicing into their prey's tough hide. Dromaeosaurus skull The skull of Dromaeosaurus shows that it had sharp teeth, large, forward-pointing eyes for judging distance, and a large brain that suggests that it was intelligent. Dromaeosaurus skull The skull of...

Oviraptosaurs

Cassowary Head

The first oviraptosaur to be discovered had a crushed skull and was lying on a nest of fossilized dinosaur eggs. The eggs belonged to an herbivore called Protoceratops. At the time of its death, the oviraptosaur was probably trying to steal the eggs to eat, and since its skull was crushed, it may have been caught and killed by an adult Protoceratops. Oviraptosaurs probably also ate berries and insects, as well as scavenging on the carcasses of dead animals. Stealing eggs Nests of Protoceratops...

Fast runner

Dinosaurs Live Water

Hypsilophodon, a small, nimble herbivore, had no armour or sharp, fighting claws. One defence when in danger was to run off on its long, bird-like legs. At high speed, Hypsilophodon might have reached speeds of around 25 km h 15 mph . Stiff tail helped Hypsilophodon keep its balance when running fast. Long foot bones increased leg length Hypsilophodon was about 6V2 ft 2 m iong. Long foot bones increased leg length Hypsilophodon was about 6V2 ft 2 m iong. These are not dinosaurs While the...

About ornithischians

Stegosaurus Anatomy

There were five main groups of ornithischians. They were all herbivores with hoofed feet and hipbones arranged like modern birds. They also had beaked mouths, apart from those in the pachycephalosaur group. Ornithischians were either bipedal or quadrupedal. Bipedal ornithischians had stiffened tails to counterbalance their bodies while feeding or running. The five groups of ornithischians were ceratopsians, with their neck frills ankylosaurs, with their body armor pachycephalosaurs, with their...

Other theropods

Ornitholestes

There was a huge variety of theropods. Most have been put into groups, like the carnosaurs, but some theropods, such as Baryonyx, Ornitholestes, and Compsognathus, do not fit into any of the established groups. Baryonyx had an unusual, crocodile-like jaw, and a savage claw on each hand. Compsognathus and Ornitholestes were two of the smallest dinosaurs. Lightweight head Chicken-sized Compsognathus had a small, pointed head with sharp, daggerlike teeth. The skull was lightly built and had huge...

Iguanodonts

Iguanodon Thumb

These dinosaurs were bipedal herbivores with long toes that ended in hooflike claws. Their arms were thick and strong, and they may have often walked on all fours, perhaps when foraging for food. Iguanodonts had a single row of tall, ridged teeth, with which they chewed their food before swallowing it. The best-known iguanodonts are Iguanodon and Ouranosaurus. Iguanodon stabbing a theropod in the neck Iguanodon stabbing a theropod in the neck Wear and tear The Iguanodon teeth above are at...

Troodontids

Near the end of the Cretaceous period, a very rare group of dinosaurs appeared. Scientists have called them troodontids. Although their body design was similar to the ornitho-mimosaurs, they were a distinct group of theropods. Troodontids had large brains for their body size. This, coupled with well-developed senses, has given them the reputation as the most intelligent of the dinosaurs. The best-known troodontid is Troodon. It had a light and delicate skeleton with slim rear limbs. Troodontid...

Nodosaurids

Armored with bony plates and dangerous spikes, but lacking the clubbed tail of the ankylosaurids, the nodosaurids were the most primitive of the ankylosaurs. They ranged in size from 5 ft 1.6 m to 25 ft 7.6 m in length. Nodosaurid fossils have been found in rocks worldwide. Ground grazer Edmontonia had small, weak teeth on the sides of its jaws. They were leaf-shaped and flattened - ideal for chopping up leafy vegetation. Edmontonia one of the largest of the nodosaurids, Edmontonia probably...

Hadrosaurs

Gryposaurus Skeleton

These herbivores are also known as duckbills, because of their toothless, ducklike bills. Hundreds of self-sharpening teeth arranged in rows lined the sides of the jaws. Hadrosaurs were bipedal. They held their bodies horizontally with their stiffened tails extended for balance. There are two main groups of hadrosaurs hadrosaurines, with flat-topped skulls, and lambeo-saurines, with hollow Bony rods head crests. along spine lt Hadrosaurs chewed food by grating the upper jaw teeth against the...

Preparing dinosaurs

Making a mold To make a mold of an original bone, liquid rubber is painted on to the surface of the bone and left to set. When the rubber has set, it is removed from the bone in sections. It is then supported by cotton gauze and surrounded with a plastic jacket. Pouring the mold The inside of the rubber molds are painted with liquid plastic and strengthened by sheets of fiberglass. The mold sections are then joined together to recreate the bone's shape, and are filled with plastic foam. Pouring...

Dilophosaurus

Dilophosaurus Skeleton

This skeleton of Dilophosaurus shows the hipbones with the forward-pointing pubis, characteristic of saurischians. Hipbones support the huge muscles that move the legs. This agile carnivore had powerful legs, and its fingers and toes had the sharp claws typical of theropods. Dilophosaurus was 19 2 ft 6 m long. hipbone The name saurischian means lizard-hipped, and saurischian dinosaurs were so called because their hipbones were like those of lizards. This means that the pubis bone pointed...

Tyrannosaurids

Of all the carnosaurs, those in the tyrannosaurid family were the largest and probably the fiercest. The most famous member, Tyrannosaurus rex, was about 46 ft 14 m long and 8 tons tonnes in weight. It is the largest land-based carnivore we know of. Tyrannosaurids not only caught and killed prey, they also scavenged dead creatures. They lived near the end of the Cretaceous period, and their remains have been found in North America and eastern Asia. Bird foot The leg bones of Tyrannosaurus rex...

Ornithopods

Paleolithic Anatomy

All the ornithopod dinosaurs were herbivores with horned beaks. Their jaws and leaf-shaped cheek teeth were ideal for chewing vegetation. They were bipedal, although some of them may have foraged for food on all fours. Their feet had three or four toes with hooflike claws, and their hands had four or five fingers. Group living Hypsilophodon may have moved in herds for protection against predatory theropods. Moving as a large group, they would have been able to warn each other of any danger,...

Ornithomimosaurs

Ostrich Anatomy

With their toothless beaks and slender feet, the ornithomimosaurs looked like giant, featherless birds. But their ostrichlike appearance also had the dinosaur features of clawed hands and a long tail. Ornithomimosaurs were long-necked and large - up to 16 ft 5 m long. They were among the fastest dinosaurs, racing on slim and powerful rear legs. A wide mouth enabled them to swallow sizable prey, such as small mammals, as well as insects and fruits. Dromiceiomimus This dinosaur had ten neck...