Dinosaurs

Contents Introduction TRIASSIC Eoraptor Coelophysis Megapnosaurus Herrerasaurus Saurosuchus Drepanosaurus Pisanosaurus Eocursor Plateosaurus Liliensternus

JURASSIC Aardonyx Dilophosaurus Cryolophosaurus Scutellosaurus Saltriovenator Monolophosaurus Ceratosaurus Allosaurus Torvosaurus Dryosaurus Brachiosaurus Camptosaurus Supersaurus Mymoorapelta

4

6 12 14 16 20 22 24 26 28 30 32 34 36 38 40 44 48 50 52 54 56 62 64 66 68 70 72

CRETACEOUS The Evolution of the Tyrannosauroids Proceratosaurus Guanlong Dilong Qianzhousaurus Albertosaurus Tarbosaurus Tyrannosaurus rex

Herbivorous Species of the Cretaceous Psittacosaurus Iguanodon Gallimimus Struthiomimus Triceratops Parasaurolophus Lambeosaurus Stegoceras Pachycephalosaurus

Oviraptoridae Oviraptor Citipati Gigantoraptor

74 76 78 80 82 84 86 88 92

100 102 106 110 112 116 120 124 128 130 134 136 140 142

Dromaeosauridae Archaeopteryx Caihong Utahraptor Deinonychus Microraptor Velociraptor Dromaeosaurus Bambiraptor Stenonychosaurus Austroraptor Saurornitholestes Halszkaraptor Pyroraptor

144 146 150 152 154 156 160 164 166 168 170 172 174 176

Reptiles from the Southern Hemisphere Carcharodontosaurus Spinosaurus Kaprosuchus Masiakasaurus Majungasaurus Carnotaurus

PTEROSAURS

178 180 184 190 192 194 196

Caviramus Dorygnathus Rhamphorhynchus Pterodactylus Pterodaustro Tupandactylus Dsungaripterus Zhenyuanopterus Quetzalcoatlus

198 200 202 204 208 212 214 216 218 220

Alphabetic Index of Species

222

Contents Introduction TRIASSIC Eoraptor Coelophysis Megapnosaurus Herrerasaurus Saurosuchus Drepanosaurus Pisanosaurus Eocursor Plateosaurus Liliensternus

JURASSIC Aardonyx Dilophosaurus Cryolophosaurus Scutellosaurus Saltriovenator Monolophosaurus Ceratosaurus Allosaurus Torvosaurus Dryosaurus Brachiosaurus Camptosaurus Supersaurus Mymoorapelta

4

6 12 14 16 20 22 24 26 28 30 32 34 36 38 40 44 48 50 52 54 56 62 64 66 68 70 72

CRETACEOUS The Evolution of the Tyrannosauroids Proceratosaurus Guanlong Dilong Qianzhousaurus Albertosaurus Tarbosaurus Tyrannosaurus rex

Herbivorous Species of the Cretaceous Psittacosaurus Iguanodon Gallimimus Struthiomimus Triceratops Parasaurolophus Lambeosaurus Stegoceras Pachycephalosaurus

Oviraptoridae Oviraptor Citipati Gigantoraptor

74 76 78 80 82 84 86 88 92

100 102 106 110 112 116 120 124 128 130 134 136 140 142

Dromaeosauridae Archaeopteryx Caihong Utahraptor Deinonychus Microraptor Velociraptor Dromaeosaurus Bambiraptor Stenonychosaurus Austroraptor Saurornitholestes Halszkaraptor Pyroraptor

144 146 150 152 154 156 160 164 166 168 170 172 174 176

Reptiles from the Southern Hemisphere Carcharodontosaurus Spinosaurus Kaprosuchus Masiakasaurus Majungasaurus Carnotaurus

PTEROSAURS

178 180 184 190 192 194 196

Caviramus Dorygnathus Rhamphorhynchus Pterodactylus Pterodaustro Tupandactylus Dsungaripterus Zhenyuanopterus Quetzalcoatlus

198 200 202 204 208 212 214 216 218 220

Alphabetic Index of Species

222

Eoraptor Even though giant dinosaurs are some of the most celebrated of the “terrible lizards,” the earliest dinosaurs got off to a small start. Eoraptor lunensis, lunensis , discovered in the roughly 230-million-year-old rocks of Argentina, for example, was only about 3 feet (1 m) long and weighed about as much as a jackal. But, small as it was, this dinosaur represents the beginnings of big things for dinosaur evolution.

When Eoraptor was discovered by paleontologist Ricardo Martínez in 1991, the dinosaur was thought to be a carnivore and related to the ancestry of later flesh-eaters such as Allosaurus and T. rex. rex . But more recent analysis has changed that interpretation. Eoraptor has been recategorized as a sauropodomorph—the group of long-necked, plant-eating dinosaurs that includes species like Brachiosaurus Brachiosaurus..

There are subtle characteristics of the dinosaur’s skeleton that places it closer to the ancestry of four-legged herbivores than carnivores. Eoraptor represents an early part of sauropodomorph evolution, between the earliest, insect-eating dinosaurs and later species. Not only that, but the fact that a sauropodomorph like Eoraptor evolved by 230 million years ago hints that dinosaurs split off into their major lineages very soon after the first dinosaurs appeared. Some of the largest dinosaurs that ever lived can trace their relatives all the way back to the depths of the Triassic.

During the time Eoraptor lived in prehistoric Argentina, the dinosaur’s habitat was a lush floodplain covered in ferns and conifer trees.

Despite the sharp teeth of Eoraptor Eoraptor,, however, the dinosaur was not the largest or most fearsome creature in its habitat. The apex predators of the time were large crocodile relatives, such as Saurosuchus Saurosuchus,, and Eoraptor was too small to eat the armored reptiles called aetosaurs or the pig-like protomammals called dicynodonts. Eoraptor probably dined on small prey, such as lizards and insects, as well as vegetation.

Despite the impressive reputation of dinosaurs, Eoraptor was probably a rare sight in its ancient habitat. Within Argentina’s Ischigualasto Formation, where Eoraptor was uncovered, dinosaur fossils represent only about 6% of the sample. There were far more crocodile relatives, protomammals, and other creatures that framed the world dinosaurs

14

STATISTICS Named: Eoraptor lunensis Year named: 1993 Age: Late Triassic, 230 million years ago Where: Argentina

were evolving in. Despite early interpretations that Eoraptor was a ra-

Length: 3.2 feet (1 m)

pacious carnivore that led the rise of the dinosaurs, instead it seems

Weight: 22 pounds (10 kg)

early dinosaurs were on the sidelines. It would take a mass extinction

Diet: Omnivore

at the end of the Triassic to turn the tide in their favor.

Group: Sauropodomorpha

Eoraptor Even though giant dinosaurs are some of the most celebrated of the “terrible lizards,” the earliest dinosaurs got off to a small start. Eoraptor lunensis, lunensis , discovered in the roughly 230-million-year-old rocks of Argentina, for example, was only about 3 feet (1 m) long and weighed about as much as a jackal. But, small as it was, this dinosaur represents the beginnings of big things for dinosaur evolution.

When Eoraptor was discovered by paleontologist Ricardo Martínez in 1991, the dinosaur was thought to be a carnivore and related to the ancestry of later flesh-eaters such as Allosaurus and T. rex. rex . But more recent analysis has changed that interpretation. Eoraptor has been recategorized as a sauropodomorph—the group of long-necked, plant-eating dinosaurs that includes species like Brachiosaurus Brachiosaurus..

There are subtle characteristics of the dinosaur’s skeleton that places it closer to the ancestry of four-legged herbivores than carnivores. Eoraptor represents an early part of sauropodomorph evolution, between the earliest, insect-eating dinosaurs and later species. Not only that, but the fact that a sauropodomorph like Eoraptor evolved by 230 million years ago hints that dinosaurs split off into their major lineages very soon after the first dinosaurs appeared. Some of the largest dinosaurs that ever lived can trace their relatives all the way back to the depths of the Triassic.

During the time Eoraptor lived in prehistoric Argentina, the dinosaur’s habitat was a lush floodplain covered in ferns and conifer trees.

Despite the sharp teeth of Eoraptor Eoraptor,, however, the dinosaur was not the largest or most fearsome creature in its habitat. The apex predators of the time were large crocodile relatives, such as Saurosuchus Saurosuchus,, and Eoraptor was too small to eat the armored reptiles called aetosaurs or the pig-like protomammals called dicynodonts. Eoraptor probably dined on small prey, such as lizards and insects, as well as vegetation.

Despite the impressive reputation of dinosaurs, Eoraptor was probably a rare sight in its ancient habitat. Within Argentina’s Ischigualasto Formation, where Eoraptor was uncovered, dinosaur fossils represent only about 6% of the sample. There were far more crocodile relatives, protomammals, and other creatures that framed the world dinosaurs

14

STATISTICS Named: Eoraptor lunensis Year named: 1993 Age: Late Triassic, 230 million years ago Where: Argentina

were evolving in. Despite early interpretations that Eoraptor was a ra-

Length: 3.2 feet (1 m)

pacious carnivore that led the rise of the dinosaurs, instead it seems

Weight: 22 pounds (10 kg)

early dinosaurs were on the sidelines. It would take a mass extinction

Diet: Omnivore

at the end of the Triassic to turn the tide in their favor.

Group: Sauropodomorpha

Megapnosaurus Dinosaur discoveries don’t always come fresh from the ground. Sometimes paleontologists discover new dinosaurs hiding in museum drawers, waiting for experts to take a second look. That’s what happened to Megapnosaurus Megapnosaurus,, a dinosaur that has sometimes been confused for other species.

In 1969, paleontologists described a new carnivorous dinosaur—“Syndinosaur—“Syntarsus” rhodesiensis. rhodesiensis. The little dinosaur was very similar to Coelophysis from North America—so similar, in fact, that some paleontologists questioned whether this new dinosaur really was a species of Coelophysis Coelophysis.. To complicate matters further, it turned out that the name “Syntarsus” had already been given to a species of beetle and could not be used for the dinosaur. This is the science of taxonomy—how species are named—and paleontologists had a taxonomic tangle to sort out.

In 2001, paleontologists suggested that this small meat-eater receive a new name, Megapnosaurus rhodesiensis rhodesiensis.. And despite previous comparisons that confused the dinosaur with Coelophysis Coelophysis,, recent analyses suggest that Megapnosaurus is more closely related to other species like Segisaurus and Camposaurus found in North America. Megapnosaurus was part of a vast proliferation of small, sleek carnivores through ancient Pangaea.

Megapnosaurus lived just before the true Age of Dinosaurs took off. The small carnivore dwelled among ancient floodplains crossed by streams and dotted with conifer trees. There were many other dinosaurs in the same habitat. Some, such as Massospondylus Massospondylus,, were big, long-necked herbivores that walked on two legs and had huge thumb claws. There were also many smaller, beaked herbivores that ran around on two legs, like Fabrosaurus Fabrosaurus..

But Megapnosaurus was not a big game hunter. Like its Triassic ancestors, this dinosaur hunted lizards, mammals, and other small morsels that lived in its habitat. The arrangement of bones in the dinosaur’s eye, in fact, hints that Megapnosaurus was primarily active at night, a perfect time to snatch a slumbering lizard or a snuffling mammal.

STATISTICS Named: Megapnosaurus rhodesiensis Year named: 2001 Age: Late Triassic, 210 million years ago Where: South Africa and Zimbabwe Length: 10 feet (3 m) Weight: 70 pounds (31.7 kg) Diet: Small vertebrates like lizards Group: Coelophysidae 20

Megapnosaurus Dinosaur discoveries don’t always come fresh from the ground. Sometimes paleontologists discover new dinosaurs hiding in museum drawers, waiting for experts to take a second look. That’s what happened to Megapnosaurus Megapnosaurus,, a dinosaur that has sometimes been confused for other species.

In 1969, paleontologists described a new carnivorous dinosaur—“Syndinosaur—“Syntarsus” rhodesiensis. rhodesiensis. The little dinosaur was very similar to Coelophysis from North America—so similar, in fact, that some paleontologists questioned whether this new dinosaur really was a species of Coelophysis Coelophysis.. To complicate matters further, it turned out that the name “Syntarsus” had already been given to a species of beetle and could not be used for the dinosaur. This is the science of taxonomy—how species are named—and paleontologists had a taxonomic tangle to sort out.

In 2001, paleontologists suggested that this small meat-eater receive a new name, Megapnosaurus rhodesiensis rhodesiensis.. And despite previous comparisons that confused the dinosaur with Coelophysis Coelophysis,, recent analyses suggest that Megapnosaurus is more closely related to other species like Segisaurus and Camposaurus found in North America. Megapnosaurus was part of a vast proliferation of small, sleek carnivores through ancient Pangaea.

Megapnosaurus lived just before the true Age of Dinosaurs took off. The small carnivore dwelled among ancient floodplains crossed by streams and dotted with conifer trees. There were many other dinosaurs in the same habitat. Some, such as Massospondylus Massospondylus,, were big, long-necked herbivores that walked on two legs and had huge thumb claws. There were also many smaller, beaked herbivores that ran around on two legs, like Fabrosaurus Fabrosaurus..

But Megapnosaurus was not a big game hunter. Like its Triassic ancestors, this dinosaur hunted lizards, mammals, and other small morsels that lived in its habitat. The arrangement of bones in the dinosaur’s eye, in fact, hints that Megapnosaurus was primarily active at night, a perfect time to snatch a slumbering lizard or a snuffling mammal.

STATISTICS Named: Megapnosaurus rhodesiensis Year named: 2001 Age: Late Triassic, 210 million years ago Where: South Africa and Zimbabwe Length: 10 feet (3 m) Weight: 70 pounds (31.7 kg) Diet: Small vertebrates like lizards Group: Coelophysidae 20

Pisanosaurus Trying to understand the early days of dinosaurs isn’t easy. Some of the earliest dinosaurs and dinosaur relatives are very rare, known from only a few bones or scattered skeletal pieces. That can lead to paleontologists having different interpretations of the same animal, and that is just what happened to Pisanosaurus mertii from Argentina.

The first bones of Pisanosaurus were discovered in 1962 in the same geologic formation that contains Eoraptor and Saurosuchus Saurosuchus..

That first find included parts of the skull, spine, ribs, hips, and limbs, which was enough to know that this animal was something new to science. But what kind of Triassic reptile was Pisanosaurus Pisanosaurus? ?

For many years, Pisanosaurus was thought to be an early ornithischian dinosaur. Ornithischia is the group of dinosaurs that came to include horned dinosaurs, armored dinosaurs, duckbilled dinosaurs, and others. In this view, Pisanosaurus might represent what the earliest ornithischians were like. But recent analyses have questioned whether Pisanosaurus is a dinosaur at all. Pisanosaurus doesn’t seem to have any specific features that connect it to ornithischian dinosaurs. Instead, Pisanosaurus might be something more ancient.

Dinosaurs belong to a broader group of reptiles called Dinosauriformes, or dinosaurs and their closest relatives. Recent studies hint that Pisanosaurus is a dinosauriform—not a true dinosaur, but a close relative. That interpretation has major implications for dinosaur evolution. Pisanosaurus might have been a protodinosaur that lived alongside some of the earliest true dinosaurs. If this is the case, then paleontologists are faced with a mystery of when and where the earliest ornithischian dinosaurs evolved. Debate about the identity of Pisanosaurus will continue.

Whatever the reptile’s classification, Pisanosaurus lived in the same floodplain environment that hosted Eoraptor and Saurosuchus Saurosuchus..

This was a warm, humid place with a strong dry and wet season. An herbivore, Pithnosaurus likely dined on horsetails and ferns that grew there while avoiding the teeth of Herrerasaurus Herrerasaurus..

STATISTICS Named: Pisanosaurus mertii Year named: 1967 Age: Late Triassic, 220 million years ago Where: Argentina Length: 3.5 feet (1.1 m) Weight: 15 pounds (6.8 kg) Diet: Plants Group: Dinosauriformes 28

Pisanosaurus Trying to understand the early days of dinosaurs isn’t easy. Some of the earliest dinosaurs and dinosaur relatives are very rare, known from only a few bones or scattered skeletal pieces. That can lead to paleontologists having different interpretations of the same animal, and that is just what happened to Pisanosaurus mertii from Argentina.

The first bones of Pisanosaurus were discovered in 1962 in the same geologic formation that contains Eoraptor and Saurosuchus Saurosuchus..

That first find included parts of the skull, spine, ribs, hips, and limbs, which was enough to know that this animal was something new to science. But what kind of Triassic reptile was Pisanosaurus Pisanosaurus? ?

For many years, Pisanosaurus was thought to be an early ornithischian dinosaur. Ornithischia is the group of dinosaurs that came to include horned dinosaurs, armored dinosaurs, duckbilled dinosaurs, and others. In this view, Pisanosaurus might represent what the earliest ornithischians were like. But recent analyses have questioned whether Pisanosaurus is a dinosaur at all. Pisanosaurus doesn’t seem to have any specific features that connect it to ornithischian dinosaurs. Instead, Pisanosaurus might be something more ancient.

Dinosaurs belong to a broader group of reptiles called Dinosauriformes, or dinosaurs and their closest relatives. Recent studies hint that Pisanosaurus is a dinosauriform—not a true dinosaur, but a close relative. That interpretation has major implications for dinosaur evolution. Pisanosaurus might have been a protodinosaur that lived alongside some of the earliest true dinosaurs. If this is the case, then paleontologists are faced with a mystery of when and where the earliest ornithischian dinosaurs evolved. Debate about the identity of Pisanosaurus will continue.

Whatever the reptile’s classification, Pisanosaurus lived in the same floodplain environment that hosted Eoraptor and Saurosuchus Saurosuchus..

This was a warm, humid place with a strong dry and wet season. An herbivore, Pithnosaurus likely dined on horsetails and ferns that grew there while avoiding the teeth of Herrerasaurus Herrerasaurus..

STATISTICS Named: Pisanosaurus mertii Year named: 1967 Age: Late Triassic, 220 million years ago Where: Argentina Length: 3.5 feet (1.1 m) Weight: 15 pounds (6.8 kg) Diet: Plants Group: Dinosauriformes 28

Cryolophosaurus Dinosaurs thrived over the entire planet. That includes the poles, challenging environments where there were months of darkness even when the world was warmer. And in the Early Jurassic of ancient Antarctica, the ancient conifer forests were stalked by Cryolophosaurus ellioti. ellioti .

Originally nicknamed “Elvisaurus” for the pompadour-like crest on its head, Cryolophosaurus was the first major dinosaur find made in Antarctica. The fossil was hard won. Not only is Antarctica very difficult to reach, but surprise snowstorms and the hard, frozen rock make work difficult for paleontologists. Nevertheless, experts have been able to recover a skull, vertebrae, ribs, and other assorted parts that give us an outline of what this carnivore looked like.

Cryolophosaurus lived around the same time as Dilophosaurus in Arizona, and, like its relative in North America, the most striking thing about Cryolophosaurus is its crest. The dinosaur from Antarctica had a ridged, fan-shaped crest right in front of its eyes. Just like other theropods, this crest was a social signal and would have been covered in a sheet of tough keratin in life.

Even though the bones of Cryolophosaurus were found in Antarctica, life on the continent was very different during the Early Jurassic. The land that now makes up Antarctica was closer to the equator and annual temperatures didn’t drop far below freezing even in the coldest months. Nevertheless, Cryolophosaurus lived in a more temperate climate where forests of conifers stood tall. And in those forests were plenty of prey.

The habitats Cryolophosaurus called home were populated with lineages left over from the Triassic. There were some small, weasel-like protomammals as well as sauropodomorph dinosaurs of varying size. Some of them, like the recently named Glacialisaurus Glacialisaurus,, got to be about as large as Cryolophosaurus itself. But there were smaller sauropodomorphs in the forests, too, about the size of a medium-sized dog. These dinosaurs, as well as the young of the larger species,

STATISTICS Named: Cryolophosaurus ellioti Year named: 1994 Age: Early Jurassic, 190 million years ago Where: Antarctica Length: 21 feet (6.4 m) Weight: 1,000 pounds (453.5 kg) Diet: Smaller vertebrates, including dinosaurs Group: Theropoda 44

Cryolophosaurus Dinosaurs thrived over the entire planet. That includes the poles, challenging environments where there were months of darkness even when the world was warmer. And in the Early Jurassic of ancient Antarctica, the ancient conifer forests were stalked by Cryolophosaurus ellioti. ellioti .

Originally nicknamed “Elvisaurus” for the pompadour-like crest on its head, Cryolophosaurus was the first major dinosaur find made in Antarctica. The fossil was hard won. Not only is Antarctica very difficult to reach, but surprise snowstorms and the hard, frozen rock make work difficult for paleontologists. Nevertheless, experts have been able to recover a skull, vertebrae, ribs, and other assorted parts that give us an outline of what this carnivore looked like.

Cryolophosaurus lived around the same time as Dilophosaurus in Arizona, and, like its relative in North America, the most striking thing about Cryolophosaurus is its crest. The dinosaur from Antarctica had a ridged, fan-shaped crest right in front of its eyes. Just like other theropods, this crest was a social signal and would have been covered in a sheet of tough keratin in life.

Even though the bones of Cryolophosaurus were found in Antarctica, life on the continent was very different during the Early Jurassic. The land that now makes up Antarctica was closer to the equator and annual temperatures didn’t drop far below freezing even in the coldest months. Nevertheless, Cryolophosaurus lived in a more temperate climate where forests of conifers stood tall. And in those forests were plenty of prey.

The habitats Cryolophosaurus called home were populated with lineages left over from the Triassic. There were some small, weasel-like protomammals as well as sauropodomorph dinosaurs of varying size. Some of them, like the recently named Glacialisaurus Glacialisaurus,, got to be about as large as Cryolophosaurus itself. But there were smaller sauropodomorphs in the forests, too, about the size of a medium-sized dog. These dinosaurs, as well as the young of the larger species,

STATISTICS Named: Cryolophosaurus ellioti Year named: 1994 Age: Early Jurassic, 190 million years ago Where: Antarctica Length: 21 feet (6.4 m) Weight: 1,000 pounds (453.5 kg) Diet: Smaller vertebrates, including dinosaurs Group: Theropoda 44

Ceratosaurus

54

Ceratosaurus nasicornis was one of the strangest dinosaurs

Allosaurus and Torvosaurus could reach nearly 40 feet (12

discovered in the 19th century. The first skeleton, which was

m) in length, about twice its size, and would have been more

nearly complete, was found in Garden Park, Colorado, in-

than a match for Ceratosaurus Ceratosaurus..

cluding a skull with a horn on the nose and another horn

Compared to the other carnivores of its time, Ceratosau-

over each eye—a Late Jurassic oddity over a century after

rus was strange. In addition to the dinosaur’s distinctive

its discovery.

horns, Ceratosaurus had very small arms, large shoulder-

Ceratosaurus was one of the many dinosaurs found

blades, bony armor embedded along its back, and legs that

within western North America’s Morrison Formation. This

were adapted more for walking than running. Perhaps, some

ancient environment was the stomping ground of famous

researchers have speculated, Ceratosaurus focused more

species like Stegosaurus and Apatosaurus Apatosaurus,, a landscape

on small prey along bodies of water than trying to compete

of winding rivers between towering stands of conifer trees

with larger carnivores. Ceratosaurus fossils are rarer than

and carpets of ferns. Like western North America today, the

those of Allosaurus Allosaurus.. Paleontologists are not sure why, but

Morrison Formation had a seasonal environment with a wet

the rarity of Ceratosaurus might mean that this dinosaur

and dry season.

preferred different prey than its larger competitors.

STATISTICS Named: Ceratosaurus nasicornis Year named: 1884

While not the largest of the Morrison Formation carni-

Much like other decorated dinosaurs, the horns of Cerato-

vores, Ceratosaurus was still an apex predator. Small, rel-

saurus were not for attack or defense. The bones were light

Where: Colorado, Wyoming, and Utah, USA

atively defenseless dinosaurs like Dryosaurus might have

and fragile, a clue that these structures were social signals.

Length: 23 feet (7 m)

been favored prey for Ceratosaurus Ceratosaurus,, as well as creatures

A keratin covering would have made them even more prom-

Weight: 1,500 pounds (680.3 kg)

that lived along the lakes and streams like lungfish. But Cer-

inent in life, meaning Ceratosaurus always cut a striking fig-

Diet: Smaller vertebrates, including other dinosaurs

atosaurus was not the largest predator of its habitat. Large

ure on the Jurassic landscape.

Group: Ceratosauridae

Age: Late Jurassic, 150 million years ago

Ceratosaurus

54

Ceratosaurus nasicornis was one of the strangest dinosaurs

Allosaurus and Torvosaurus could reach nearly 40 feet (12

discovered in the 19th century. The first skeleton, which was

m) in length, about twice its size, and would have been more

nearly complete, was found in Garden Park, Colorado, in-

than a match for Ceratosaurus Ceratosaurus..

cluding a skull with a horn on the nose and another horn

Compared to the other carnivores of its time, Ceratosau-

over each eye—a Late Jurassic oddity over a century after

rus was strange. In addition to the dinosaur’s distinctive

its discovery.

horns, Ceratosaurus had very small arms, large shoulder-

Ceratosaurus was one of the many dinosaurs found

blades, bony armor embedded along its back, and legs that

within western North America’s Morrison Formation. This

were adapted more for walking than running. Perhaps, some

ancient environment was the stomping ground of famous

researchers have speculated, Ceratosaurus focused more

species like Stegosaurus and Apatosaurus Apatosaurus,, a landscape

on small prey along bodies of water than trying to compete

of winding rivers between towering stands of conifer trees

with larger carnivores. Ceratosaurus fossils are rarer than

and carpets of ferns. Like western North America today, the

those of Allosaurus Allosaurus.. Paleontologists are not sure why, but

Morrison Formation had a seasonal environment with a wet

the rarity of Ceratosaurus might mean that this dinosaur

and dry season.

preferred different prey than its larger competitors.

STATISTICS Named: Ceratosaurus nasicornis Year named: 1884

While not the largest of the Morrison Formation carni-

Much like other decorated dinosaurs, the horns of Cerato-

vores, Ceratosaurus was still an apex predator. Small, rel-

saurus were not for attack or defense. The bones were light

Where: Colorado, Wyoming, and Utah, USA

atively defenseless dinosaurs like Dryosaurus might have

and fragile, a clue that these structures were social signals.

Length: 23 feet (7 m)

been favored prey for Ceratosaurus Ceratosaurus,, as well as creatures

A keratin covering would have made them even more prom-

Weight: 1,500 pounds (680.3 kg)

that lived along the lakes and streams like lungfish. But Cer-

inent in life, meaning Ceratosaurus always cut a striking fig-

Diet: Smaller vertebrates, including other dinosaurs

atosaurus was not the largest predator of its habitat. Large

ure on the Jurassic landscape.

Group: Ceratosauridae

Age: Late Jurassic, 150 million years ago

Brachiosaurus Few dinosaurs stood taller than Brachiosaurus altithorax. altithorax . Named the “arm lizard” for the length of the dinosaur’s column-like forelimbs, this sauropod dinosaur reached high into the trees to nibble on conifer branches that other plant-eaters could only ever dream of reaching.

The first Brachiosaurus fossils known to paleontologists were uncovered in 1903 in western Colorado. Said to be one of the largest dinosaurs ever found when it was discovered, the original fossil only included a handful of the giant’s bones. The find included an arm bone, some of the leg bones, several vertebrae, and a few ribs. Still, even those pieces were enough to know that Brachiosaurus was different from other sauropod dinosaurs of the time.

Paleontologists have turned up additional bones since then—including parts of the skull—but Brachiosaurus is a very rare dinosaur.

Experts are still awaiting the discovery of a more complete skeleton.

And experts have turned to related dinosaurs to fill in some of the gaps. A dinosaur found in Tanzania, Giraffatitan Giraffatitan,, was once thought to be a species of Brachiosaurus and its bones are sometimes used as a model for what’s still missing from Brachiosaurus Brachiosaurus..

A sauropod, Brachiosaurus stood out amongst its neighbors during the time of the Late Jurassic Morrison Formation. The long arms of Brachiosaurus elevated the dinosaur’s chest and neck into a much higher resting position. The dinosaur is also thought to have had broad, spoon-shaped teeth, and likely fed high up on conifer trees to help avoid competition with other, shorter herbivores like Camarasaurus and Apatosaurus Apatosaurus..

The heart of Brachiosaurus had to pump blood high up the neck, requiring a massive heart and blood pressure twice that of a giraffe.

To get around this, Brachiosaurus and similar dinosaurs moved their heads side-to-side more often than up-and-down. This allowed Brachiosaurus to stand in place and graze over a broad area before moving on to its next meal.

STATISTICS Named: Brachiosaurus altithorax Year named: 1903 Age: Late Jurassic, 150 million years ago

66 To date, no one has ever found a

Where: Western United States

complete Brachiosaurus altithorax skull.

Length: 65 feet (19.8 m) Weight: 50 tons (45.3 t)

66

Most restorations of this iconic dinosaur are based on the skull of Giraffatitan, a related dinosaur found in Tanzania. New discoveries

Diet: Conifers and other plants

may change what we think Brachiosaurus

Group: Brachiosauridae

looked like.

Brachiosaurus Few dinosaurs stood taller than Brachiosaurus altithorax. altithorax . Named the “arm lizard” for the length of the dinosaur’s column-like forelimbs, this sauropod dinosaur reached high into the trees to nibble on conifer branches that other plant-eaters could only ever dream of reaching.

The first Brachiosaurus fossils known to paleontologists were uncovered in 1903 in western Colorado. Said to be one of the largest dinosaurs ever found when it was discovered, the original fossil only included a handful of the giant’s bones. The find included an arm bone, some of the leg bones, several vertebrae, and a few ribs. Still, even those pieces were enough to know that Brachiosaurus was different from other sauropod dinosaurs of the time.

Paleontologists have turned up additional bones since then—including parts of the skull—but Brachiosaurus is a very rare dinosaur.

Experts are still awaiting the discovery of a more complete skeleton.

And experts have turned to related dinosaurs to fill in some of the gaps. A dinosaur found in Tanzania, Giraffatitan Giraffatitan,, was once thought to be a species of Brachiosaurus and its bones are sometimes used as a model for what’s still missing from Brachiosaurus Brachiosaurus..

A sauropod, Brachiosaurus stood out amongst its neighbors during the time of the Late Jurassic Morrison Formation. The long arms of Brachiosaurus elevated the dinosaur’s chest and neck into a much higher resting position. The dinosaur is also thought to have had broad, spoon-shaped teeth, and likely fed high up on conifer trees to help avoid competition with other, shorter herbivores like Camarasaurus and Apatosaurus Apatosaurus..

The heart of Brachiosaurus had to pump blood high up the neck, requiring a massive heart and blood pressure twice that of a giraffe.

To get around this, Brachiosaurus and similar dinosaurs moved their heads side-to-side more often than up-and-down. This allowed Brachiosaurus to stand in place and graze over a broad area before moving on to its next meal.

STATISTICS Named: Brachiosaurus altithorax Year named: 1903 Age: Late Jurassic, 150 million years ago

66 To date, no one has ever found a

Where: Western United States

complete Brachiosaurus altithorax skull.

Length: 65 feet (19.8 m) Weight: 50 tons (45.3 t)

66

Most restorations of this iconic dinosaur are based on the skull of Giraffatitan, a related dinosaur found in Tanzania. New discoveries

Diet: Conifers and other plants

may change what we think Brachiosaurus

Group: Brachiosauridae

looked like.

Psittacosaurus The term “horned dinosaur” often conjures up images of enormous, scaly herbivores festooned with impressive horns—dinosaurs like Triceratops,, Styracosaurus Triceratops Styracosaurus,, and Torosaurus Torosaurus.. But the horned dinosaur family was small for much of their early history. And among those little, early ceratopsids, few have had such outsized influence on what we think about horned dinosaurs as Psittacosaurus mongoliensis. mongoliensis .

There may be as many as a dozen known species of Psittacosaurus,, all with their own slight differences in horn and skull shape. But rus the iconic Psittacosaurus Psittacosaurus—the —the first to be named and perhaps the best known—is Psittacosaurus mongoliensis from the Gobi Desert.

The first Psittacosaurus fossils known to paleontologists came from expeditions led by the American Museum of Natural History to Mongolia carried out in the 1920s. A driver named Wong, a driver for the expedition, found what turned out to be a partial skeleton and complete skull of an unknown dinosaur. The dinosaur had a parrot-like beak at the front of its boxy skull. This is where the dinosaur got its name from, as Psittacosaurus translates to “parrot lizard.”

The geographical and temporal range of Psittacosaurus species is impressive. Many dinosaurs are known only from a few bones from a single skeleton or a collection of bones all attributable to one species.

But various Psittacosaurus lived in what’s now Mongolia and China between 126 and 101 million years ago, some leaving complete skeletons. In fact, some Psittacosaurus are so well-preserved that we know what color they were.

A particular Psittacosaurus found in China and known as SMF R 4970 has been incredibly informative for paleontologists. In addition to a complete, articular skeleton, the fossil includes a great deal of skin impressions and even bristle-like feathers.

Paleontologists started reporting more dinosaurs with preserved feathers and feather-like structures in the late 1990s. Most of these were theropods that were more or less related to the earliest birds.

STATISTICS Named: Psittacosaurus mongoliensis Year named: 1923 Age: Early Cretaceous, over 101 million years ago Where: Mongolia Length: 6.5 feet (1.9 m) Weight: 44 pounds (19.9 kg) Diet: Ferns and similar plants Group: Ceratopsia 103

Psittacosaurus The term “horned dinosaur” often conjures up images of enormous, scaly herbivores festooned with impressive horns—dinosaurs like Triceratops,, Styracosaurus Triceratops Styracosaurus,, and Torosaurus Torosaurus.. But the horned dinosaur family was small for much of their early history. And among those little, early ceratopsids, few have had such outsized influence on what we think about horned dinosaurs as Psittacosaurus mongoliensis. mongoliensis .

There may be as many as a dozen known species of Psittacosaurus,, all with their own slight differences in horn and skull shape. But rus the iconic Psittacosaurus Psittacosaurus—the —the first to be named and perhaps the best known—is Psittacosaurus mongoliensis from the Gobi Desert.

The first Psittacosaurus fossils known to paleontologists came from expeditions led by the American Museum of Natural History to Mongolia carried out in the 1920s. A driver named Wong, a driver for the expedition, found what turned out to be a partial skeleton and complete skull of an unknown dinosaur. The dinosaur had a parrot-like beak at the front of its boxy skull. This is where the dinosaur got its name from, as Psittacosaurus translates to “parrot lizard.”

The geographical and temporal range of Psittacosaurus species is impressive. Many dinosaurs are known only from a few bones from a single skeleton or a collection of bones all attributable to one species.

But various Psittacosaurus lived in what’s now Mongolia and China between 126 and 101 million years ago, some leaving complete skeletons. In fact, some Psittacosaurus are so well-preserved that we know what color they were.

A particular Psittacosaurus found in China and known as SMF R 4970 has been incredibly informative for paleontologists. In addition to a complete, articular skeleton, the fossil includes a great deal of skin impressions and even bristle-like feathers.

Paleontologists started reporting more dinosaurs with preserved feathers and feather-like structures in the late 1990s. Most of these were theropods that were more or less related to the earliest birds.

STATISTICS Named: Psittacosaurus mongoliensis Year named: 1923 Age: Early Cretaceous, over 101 million years ago Where: Mongolia Length: 6.5 feet (1.9 m) Weight: 44 pounds (19.9 kg) Diet: Ferns and similar plants Group: Ceratopsia 103

Caihong For a very long time, paleontologists envisioned dinosaurs

This Jurassic didn’t just have feathers, but was covered

with very drab colors. Large species, especially, were of-

in thick plumage. And in those preserved feathers were

ten depicted as shades of gray, brown, and green. But we

pigment-carrying bodies called melanosomes. By study-

now know that at least some dinosaurs were very bright-

ing these tiny structures, experts discerned that Caihong

ly colored. The Late Jurassic dinosaur Caihong juji was

had shiny, iridescent feathers around its head and neck

practically a rainbow-colored dinosaur.

like those of some hummingbirds. Rather than being the

A relative of dromaeosaurs and Archaeopteryx Archaeopteryx,, Caihong was a small dinosaur. An adult could stand in the palm of

dark sheen of Microraptor Microraptor,, some of the Caihong feathers were rainbow-colored.

your hand. Back in the Jurassic, many different feathered

Precisely why Caihong was such a colorful dinosaur is a

dinosaurs lived in the same forests. Most discovered to

puzzle. Carrying striking colors could be a risk for a small

date were small and seem adapted to life in the trees. But

dinosaur, making it more visible to larger carnivores. But

even in a place with many other fuzzy dinosaurs, this Late

bright coloration can be very important for social signal-

Jurassic carnivore would have been immediately recog-

ing, such as finding a mate or facing off against rivals.

nizable. Not only did Caihong have a small crest on top

And if Caihong could be so brightly colored, then there

of its snout, but this dinosaur was brightly colored. The

are likely other dinosaurs with brilliant hues that have yet

feathers of Caihong were densely packed.

to be uncovered.

STATISTICS Named: Caihong juji Year named: 2018 Age: Late Jurassic, 161 million years old Where: China Length: 16 inches (0.4 m) Weight: 1 pound (0.4 kg) Diet: Insects and small prey Group: Anchiornithidae 150

Caihong For a very long time, paleontologists envisioned dinosaurs

This Jurassic didn’t just have feathers, but was covered

with very drab colors. Large species, especially, were of-

in thick plumage. And in those preserved feathers were

ten depicted as shades of gray, brown, and green. But we

pigment-carrying bodies called melanosomes. By study-

now know that at least some dinosaurs were very bright-

ing these tiny structures, experts discerned that Caihong

ly colored. The Late Jurassic dinosaur Caihong juji was

had shiny, iridescent feathers around its head and neck

practically a rainbow-colored dinosaur.

like those of some hummingbirds. Rather than being the

A relative of dromaeosaurs and Archaeopteryx Archaeopteryx,, Caihong was a small dinosaur. An adult could stand in the palm of

dark sheen of Microraptor Microraptor,, some of the Caihong feathers were rainbow-colored.

your hand. Back in the Jurassic, many different feathered

Precisely why Caihong was such a colorful dinosaur is a

dinosaurs lived in the same forests. Most discovered to

puzzle. Carrying striking colors could be a risk for a small

date were small and seem adapted to life in the trees. But

dinosaur, making it more visible to larger carnivores. But

even in a place with many other fuzzy dinosaurs, this Late

bright coloration can be very important for social signal-

Jurassic carnivore would have been immediately recog-

ing, such as finding a mate or facing off against rivals.

nizable. Not only did Caihong have a small crest on top

And if Caihong could be so brightly colored, then there

of its snout, but this dinosaur was brightly colored. The

are likely other dinosaurs with brilliant hues that have yet

feathers of Caihong were densely packed.

to be uncovered.

STATISTICS Named: Caihong juji Year named: 2018 Age: Late Jurassic, 161 million years old Where: China Length: 16 inches (0.4 m) Weight: 1 pound (0.4 kg) Diet: Insects and small prey Group: Anchiornithidae 150

Velociraptor Before 1993, Velociraptor mongoliensis was not a celebrity dinosaur.

Initially known from a skull and a claw found during a 1923 expedition to Mongolia, the dinosaur was rather obscure. Thanks to the bigscreen adaptation of Jurassic Park, Park , however, this turkey-sized dinosaur was immediately placed in the celebrity spotlight—even though the real animal was very different from its Hollywood counterparts.

Multiple Velociraptor skeletons have been found since the initial discovery, making this dromaeosaur one of the best-known species of all. Paleontologists have even discovered a Velociraptor locked in combat with a Protoceratops when the two were buried and fossilized—famously known as “the Fighting Dinosaurs.” Though much smaller and more slender than other dromaeosaurs like Deinonychus Deinonychus,, Velociraptor was still an accomplished hunter.

In life, Velociraptor roamed the dune-covered landscapes of Cretaceous Mongolia about 73 million years ago. These were the same habitats inhabited by Protoceratops Protoceratops,, Oviraptor Oviraptor,, and other familiar species, and collapsing sand dunes are at least partially responsible for why we know Velociraptor so much better than some of its relatives.

Velociraptor is one of the few known dromaeosaurs with direct evidence of feathery body coverings. Often, which dinosaurs were feathered is inferred through the relationships between feathered species and where paleontologists expect feathers evolved on the dinosaur family tree. But even though paleontologists have only found Velociraptor bones so far, one of the lower arm bones in some specimens show a row of dots—quill knobs that were anchor points for long arm feathers. This discovery left little doubt that Velociraptor was a very feathery dinosaur and that its relatives were also covered in elaborate plumage.

STATISTICS Named: Velociraptor mongoliensis Year named: 1924 Age: Late Cretaceous, 73 million years ago Where: Mongolia Length: 7 feet (2.1 m) Weight: 40 pounds (18.1 kg) Diet: Smaller dinosaurs and vertebrates Group: Dromaeosauridae 160

Velociraptor Before 1993, Velociraptor mongoliensis was not a celebrity dinosaur.

Initially known from a skull and a claw found during a 1923 expedition to Mongolia, the dinosaur was rather obscure. Thanks to the bigscreen adaptation of Jurassic Park, Park , however, this turkey-sized dinosaur was immediately placed in the celebrity spotlight—even though the real animal was very different from its Hollywood counterparts.

Multiple Velociraptor skeletons have been found since the initial discovery, making this dromaeosaur one of the best-known species of all. Paleontologists have even discovered a Velociraptor locked in combat with a Protoceratops when the two were buried and fossilized—famously known as “the Fighting Dinosaurs.” Though much smaller and more slender than other dromaeosaurs like Deinonychus Deinonychus,, Velociraptor was still an accomplished hunter.

In life, Velociraptor roamed the dune-covered landscapes of Cretaceous Mongolia about 73 million years ago. These were the same habitats inhabited by Protoceratops Protoceratops,, Oviraptor Oviraptor,, and other familiar species, and collapsing sand dunes are at least partially responsible for why we know Velociraptor so much better than some of its relatives.

Velociraptor is one of the few known dromaeosaurs with direct evidence of feathery body coverings. Often, which dinosaurs were feathered is inferred through the relationships between feathered species and where paleontologists expect feathers evolved on the dinosaur family tree. But even though paleontologists have only found Velociraptor bones so far, one of the lower arm bones in some specimens show a row of dots—quill knobs that were anchor points for long arm feathers. This discovery left little doubt that Velociraptor was a very feathery dinosaur and that its relatives were also covered in elaborate plumage.

STATISTICS Named: Velociraptor mongoliensis Year named: 1924 Age: Late Cretaceous, 73 million years ago Where: Mongolia Length: 7 feet (2.1 m) Weight: 40 pounds (18.1 kg) Diet: Smaller dinosaurs and vertebrates Group: Dromaeosauridae 160