J ephyrosaurus was a small twolegged plant eater but it was a swift runner

Zephyrosaurus Skull

Zephyrosaurus was a member of the dinosaur family called Hypsilopho-dontids. They all had long legs and feet that were perfect for sprinting. This family has been nicknamed the "dinosaur gazelles."

Zephyrosaurus

A GUIDE TO THE DINOSAURS IN THIS BOOK

TRIASSIC PERIOD-FROM 245 MILLION YEARS AGO TO 205 MILLION YEARS AGO JURASSIC PERIOD-FROM 205 MILLION YEARS AGO TO 140 MILLION YEARS AGO CRETACEOUS PERIOD-FROM 140 MILLION YEARS AGO TO 65 MILLION YEARS AGO

ANKYLOSAURUS

(ANK-EE-hw-SAlV-ms) Jten

What Its Name Means: Stiff lizard ^JpjCTfflflwjWfc, What It Ate: Plants M When It Lived: The Late Cretaceous Period Where Fossils Were Found: Western

North America Length: Up to 25 feet long

DEINONYCHUS fiB

What Its Name Means: Terrible claw ^^^^^ ^ ■>? ; What It Ate: Meat &' -When It Lived: The Early Cretaceous Period Where Fossils Were Found: Western

North America Length: Up to 11 feet long

ERLIKOSAURUS

What Its Name Means: Erlik's lizard

When It Lived: The Late Cretaceous Period Where Fossils Were Found: Mongolia,

East Asia Length: Up to 12 feet long

BARYONYX

What It Ate: Meat Q " ■ fet^il When It Lived: The Early Cretaceous Period ft " Where Fossils Were Found: England, Europe, and Niger, Africa Length: Up to 30 feet long

CHASMOSAURUS

What Its Name Means: Ravine reptile What It Are: Plants

When It Lived: The Late Cretaceous Period Where Fossils Were Found: Western _ yi4^ North America ^gBPtrfafriKj^! *^ 1 *.• j

Length: Up to 17 feet long

FABROSAURUS

When It Lived: The Early Jurassic Period Where Fossils Were Found: South

Africa, Africa Length: Up to 4 feet long

GALUMIMUS

(GAL-h-MIMEus)

What Its Name Means: Chicken mimic What It Ate: Plants and meat When It Lived: The Late Cretaceous Period Where Fossils Were Found: Mongolia,

Length: Up to 17 feet long ^^^

JANENSCHIA

(yah-NEN-shee-ah) What Its Name Means: In honor of Wilhelm Janesch

When It Lived: The Late Jurassic period

Where Fossils Were Found: East "" rl?

Africa, Africa Length: Up to 60 feet long

HERRERASAURUS

What Its Name Means: Herrera's lizard (To honor Don Victoria Herrera, a rancher from the region in Argentina where the fossils were

When It Lived: The Late Triassic Period

Where Fossils Were Found: Argentina, au^^

Length: Up to 18 feet long

KENTROSAURUS

(KEN-iro-SAW-rus)

What Its Name Means: Sharp-pointed lizard What It Ate: Plants

When It Lived: The Late Jurassic Period

Where Fossils Were Found: East

Length: Up to 17 feet long & 1

LEPTOCERATOPS

(LEP-toh-SER-a-tops)

What Its Name Means: Slender horn face What It Ate: Plants

When It Lived: The Early Cretaceous Period

Where Fossils Were Found: Western ^^^^^^^^^

IGUANODON JPlftW

What Its Name Means: Iguana tooth js \\ What It Ate: Plants

When It Lived: The Early Cretaceous Period Where Fossils Were Found: Europe and Asia Length: Up to 25 feet long

MAIASURA

What Its Name Means: Good mother reptile What It Ate: Plants

When It Lived: The Late Cretaceous Period Where Fossils Were Found: Montana,

United States Bl Length: Up to 30 feet long ^ ^^

QUAESITOSAURUS

What Its Name Means: Uncommon reptile (So named because of a strange bony tube in its skull) What It Ate: Plants ^Tr'i^".'~ ' jj When It Lived: The Late Cretaceous Period Where Fossils Were Found: Mongolia,

East Asia Length: Up to 50 feet long

When It Lived: The Late Cretaceous Period Where Fossils Were Found: North America Length: Up to 17 feet long

RIOJASAURUS

What Its Name Means: Lizard from Rioja

(a province of Argentina) JjP What It Ate: Plants ffiM^i) When It Lived: The Late Triassic Period ^ Where Fossils Were Found: Argentina,

South America Length: Up to 36 feet long

OVIRAPTOR

(ove-ib-RAP-tor) t What Its Name Means: Egg thief .p^a^ft^

When It Lived: The Late Cretaceous Period ^ I ^ Where Fossils Were Found: Mongolia, V ^

East Asia Length: Up to 6 feet long

STEGOSAURUS

What Its Name Means: Plated reptile

What It Ate: Plants

When It Lived: The Late Jurassic Period Where Fossils Were Found: Western United States, North America

PENTACERATOPS

What Its Name Means: Five-horn face What It Ate: Plants

When It Lived: The Late Cretaceous Period

Where Fossils Were Found: New j y^

Mexico, United States ' -Length: Up to 20 feet long ^

TYRANNOSAURUS REX

(ie-RAN-o-saw-ms rex)

What Its Name Means: Tyrant lizard

What It Ate: Meat

When It Lived: The Late Cretaceous Period

Where Fossils Were Found: Western North

America and People's Republic

of China, East Asia

Length: Up to 40 feet long .■V^sSfji5

f

K

ULTRASAUROS

(UL-tra-SAiV-ros)

What Its Name Means: Lizard beyond others

What It Ate: Plants

When It Lived: The Late Jurassic Period

Where Fossils Were Found: North America

Length: Up to 100 feet long

S i

VELOCIRAPTOR

(ve/AH-see-RAP-tor)

What Its Name Means: Swift thief ,

What It Ate: Meat

When It Lived: The Late Cretaceous Period

ri

Where Fossils Were Found: Mongolia, f

People's Republic of China, and

Kazakhstan, East Asia

Length: Up to 6 feet long

(wahn-NAN-o-SAW-rms)

What Its Name Means: Lizard from southern Anhui Province What It Ate: Plants

When It Lived: The Late Cretaceous Period Where Fossils Were Found: People's

Republic of China, East Asia Length: Up to 5 feet long

XENOTARSOSAURUS

What Its Name Means: Strange ankle lizard

What It Ate: Meat

When It Lived: The Late Cretaceous Period Where Fossils Were Found: Argentina,

South America Length: Up to 12 feet long

YANGCHUANOSAURUS

(YANG-chew-an-o-SAW-rus) What Its Name Means: Lizard from

Yangchuan County What It Ate: Meat

When It Lived: The Late Jurassic Period Where Fossils Were Found: People's

Republic of China, East Asia Length: Up to 33 feet long

ZEPHYROSAURUS

foef-EAR-roe-SAW-ms)

What Its Name Means: West wind lizard

What It Ate: Plants

When It Lived: The Early Cretaceous Period Where Fossils Were Found: Western United

States, North America Length: Up to 6 feet long

WHAT HAPPENED TO THE DINOSAURS?

Every one knows that the dinosaurs died out (or became extinct) about 65 million years ago. Does this mean that the dinosaurs were failures? No! Most plants and animals that have ever lived are extinct.

our study of the fossil record shows that most kinds of animals only live for a certain amount of time. Most mammals that are extinct lived for 1 or 2 million years. Some kinds of snails and clams lived for 10 to 12 million years before becoming extinct.

Dinosaurs survived for 160 million years, making them far more successful than human animals, who have only been around for about 2 million years. Dinosaur families were constantly going extinct. Over that 160-million-year period, the dinosaurs that lived on Earth changed completely 30 times!

Herrerasaurus, which lived 225 million years ago, had been extinct for 75 million years before Stegosaurs appeared. And Stegosaurs were extinct for nearly 85 million years before Tyran-nosaurs appeared. Tyrannosaurs, along with Triceratops and Edmontosaurs, were among the last dinosaurs on Earth. But in one sense dinosaurs are not extinct at all, because their genetic material lives on in birds. In fact, some dinosaur scientists now consider that birds are dinosaurs!

We always want to say why something became extinct even though we almost never know for sure. Scientists have many different ideas about why the dinosaurs became extinct. The most exciting idea is that a comet or asteroid —maybe as large as six miles wide— smashed into the earth 65 million years ago. The impact would have formed a crater 100 miles across. Clouds of dust would have circled the globe, causing temperatures to drop. Storms and wildfires would have swept around the world, causing darkness that would have lasted for months. Lower temperatures might have brought freezing weather that could have killed the dinosaurs. Most of the plants on Earth would have died without sunlight, and only their seeds would have survived.

But other scientists believe that explosions of several large volcanoes could have caused the same kinds of conditions. They think the extinction of the dinosaurs can be explained without supposing that a comet smashed into the planet. Still other scientists think that a comet combined with volcanic explosions was the cause of the dinosaurs' extinction.

Whatever caused the catastrophe of 65 million years ago, not all animals died out. Many survived after the dinosaurs were gone. Sharks, bony fish, frogs, turtles, crocodiles, lizards, and mammals spread across the earth and thrived. This has led some scientists to think that the extinction of the dinosaurs may have happened more slowly, perhaps due to a change in climate.

The climate had been very warm for most of the dinosaurs' long reign, but started to cool a little toward the end. Perhaps this saved the smaller animals, who could seek refuge or hibernate. And, since water temperature changes far more slowly than air temperature, perhaps this saved the sharks and other marine animals. Some scientists think that the dinosaurs became extinct because they couldn't adjust to new forms of plant life, or that diseases killed off whole populations. But we may never find the evidence to say if these theories are right or wrong. The sad fact is, we may never know for sure just what killed off the dinosaurs.

0 0

Post a comment