Dinosauria - · PDF fileNo one knows how it ... and other reptiles come from a group of...

ISBN 978 1 7418 3776 4DIN

OSAURIA

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The First Living Things

THE FIRST LIFE ON EARTH probably appeared about 3,800 millionyears ago. No one knows how it began, but the first creatures livedin the oceans. There was not enough oxygen in the air on land for

creatures to breathe. Ultraviolet radiation (rays from the Sun that causesunburn) was at deadly levels.

AN EXPLOSION OF LIFEDuring the Cambrian period, Earth’s warm, shallow seas were

full of new life forms. The largest and meanest of these was the 25-in(63.5 cm) Anomalocaris. Smaller animals like Hallucigenia and Wiwaxia had

to protect themselves from such predators. Pikaia, a small worm-like creature,had a rod running down its back. It was probably an early ancestor of vertebrates(animals with backbones), including fish, reptiles, birds, and mammals today.

Trilobite

Pikaia

Opabinia

Sanctacaris

Leanchoilia

AnomalocarisJellyfish

Wiwaxia

Hallucigenia

The earliest life forms were simple bacteria. It took a very, very long time(2,500 million years) for more complex life to develop. The first aquaticanimals with shells or skeletons, such as shellfish, corals, and starfish,appeared 570 million years ago. Then, 550 million years ago, many newand different life forms appeared suddenly in an “explosion of life.”

TODAY’S REPTILES—turtles, tortoises, lizards, snakes and crocodiles—

are the survivors of a group of animals that once dominated the Earth

for 250 million years. While dinosaurs roamed the land, pterosaurs soared

in the skies and ichthyosaurs, pterosaurs and pliosaurs swam in the seas.

Discover the amazing story of the reptiles in this book.

DDiinnoossaauurriiaaTHE RISE OF THE

REPTILES

DDiinnoossaauurriiaa

THE RISE OF THE

REPTILES

(UK)Job: E2-23540 Title: Dinofiles - Reign Of The Reptiles

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First published in 2012 by Orpheus Books Ltd.,6 Church Green, Witney, Oxfordshire OX28 4AW, England

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Copyright © 2012 Orpheus Books Ltd.

Created and produced by Nicholas Harris, Sarah Hartley, Erica Williams, Katie Sexton and Ruth Symons

Orpheus Books Ltd.

Illustrated by Julius T. Csotonyi, Steve Kirk, Simon Mendez, Nicki Palin, Peter Scott, John Sibbick and Studio InklinkIllustration copyright © Julius T. Csotonyi 21BLIllustration copyright © John Sibbick 27TR and 31.

Text by Olivia Brookes

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic,

mechanical, photocopying, recording or otherwise, without the prior writtenpermission of the copyright owner.

ISBN 978 1 7418 3776 4

A CIP record for this book is available from the British Library

Printed and bound in China


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DDiinnoossaauurriiaaTHE RISE OF THE

REPTILES

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IntroductionContents

Introduction 5

Geological time 6

The first living things 8

First life on land 10

Coal swamps 12

Permian world 14

Reptiles of land, sea and air 16

The dinosaurs 18

Rhamphorhynchus 20

Pteranodon 22

Quetzalcoatlus 24

Ichthyosaurus 26

Plesiosaurus 28

Kronosaurus 30

Index 32

Today’s lizards, snakes, crocodiles, and other reptiles come from agroup of animals that once ruled Earth for 250 million years—much longer than the mammals have been in charge (that’s just

65 million years and counting). At first, these creatures were small andlizardlike. They lived in swamps in the Late Carboniferous period. Whenthe world became drier in the Permian period, they moved onto land andslowly became more like the reptiles we know today.

Some of these reptiles evolved into dinosaurs and became the largestanimals that ever roamed Earth. Other kinds developed wings,becoming the first backboned animals to fly. Still others took to thewater and, over time, became gigantic predators of the sea.

The first part of this book tells the amazing story of how the reptilescame to rule Earth. The second part focuses on the flying and marinereptiles that lived alongside the dinosaurs. Much more informationabout the dinosaurs themselves can be found in other titles in theDinosauria series.



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6 7

Geologic Time

EARTH is 4,600million years old.Earth’s history is

measured in geologictime: spans of millionsof years. A “recent”event in geologic timemay have happened inthe last 1 million years. Geologic time is splitinto periods (right).Dinosaurs lived duringthe Triassic, Jurassic,and Cretaceous periods.They first appearedabout 230 million yearsago. But life began morethan 3,500 million yearsearlier. During that time,many kinds of plantsand animals lived anddied out. Mountainsgrew up and wore down.Sea levels rose and fell.Even the continentsmoved very, very slowlyaround the globe.

EARTH: THE EARLY YEARSJust a few million years after Earth wasborn, volcanoes erupted, blasting gasesinto the air. These gases, hydrogen, carbondioxide, water vapor, and nitrogen, formedEarth’s atmosphere. When the water vapor cooled, clouds formed.Soon, rain began to fall. It rained for thousands of years, filling upthe great basins in the land to make Earth’s great oceans.

If we could squeeze 4,600 millionyears of Earth’s history into just 12 hours, the Precambrian periodwould take 10 hours 30 minutes.From the first living things to thepresent day would take up 1 hour30 minutes (the dinosaurs died outjust 9 minutes ago!). All of humanhistory took place in the lastsecond.

QUAT E RNAR Y

T E R T I A R Y

millionyears ago

1.8

First modernhumans

C R E TA C E O U S

J U R A S S I C

T R I A S S I C

P E R M I A N

CARBONIFEROUS

D E V O N I A N

S I L U R I A N

O R DO V I C I A N

C A M B R I A N

PRECAMBRIAN

Dinosaursextinct

Firstflowering plants

First birds

First mammalsFirst dinosaurs

First archosaurs

First mammal-like reptiles

First reptiles

Oldest fossils

Formation ofEarth

First shellfish

First jawless fish

First land plants

First amphibiansFirst lobefin fishFirst insectsFirst fish withjaws

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8 9

The First Living Things

THE FIRST LIFE ON EARTH probably appeared about 3,800 millionyears ago. No one knows how it began, but the first creatures livedin the oceans. There was not enough oxygen in the air on land for

creatures to breathe. Ultraviolet radiation (rays from the Sun that causesunburn) was at deadly levels.

AN EXPLOSION OF LIFEDuring the Cambrian period, Earth’s warm, shallow seas were

full of new life forms. The largest and meanest of these was the 25-in(63.5 cm) Anomalocaris. Smaller animals like Hallucigenia and Wiwaxia had

to protect themselves from such predators. Pikaia, a small worm-like creature,had a rod running down its back. It was probably an early ancestor of vertebrates(animals with backbones), including fish, reptiles, birds, and mammals today.

Trilobite

Pikaia

Opabinia

Sanctacaris

Leanchoilia

Anomalocaris

Jellyfish

Wiwaxia

Hallucigenia

The earliest life forms were simple bacteria. It took a very, very long time(2,500 million years) for more complex life to develop. The first aquaticanimals with shells or skeletons, such as shellfish, corals, and starfish,appeared 570 million years ago. Then, 550 million years ago, many newand different life forms appeared suddenly in an “explosion of life.”



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From Fish to Amphibians

10

FISH evolved rapidlyduring the Silurianand Devonian

periods. The earliest fishhad no fins or jaws, butonce they had developedthese, they became activepredators. Two types offish emerged. The firstgroup had hard, bonyskeletons and lived in seasand freshwater rivers. Thesecond group had softcartilage skeletons, likesharks have today.

Eurypterids were arthropods,creatures with hard outerskeletons and jointed

limbs. They werelarge predators.

The first fish (below)had protective armor

but no jaws. Theyate scraps ofdead seaanimals. Trilobites (above)

scuttled along the seabedor paddled through thewater with their legs.Their name means “threelobes” for their three-part bodies.

CRAWLING ONTO LANDGradually, some lobefin fish like Eusthenopteroncould pull themselves out of the water and crawl onland using their fins (above). They ate insects andspiders. These fish were ancestors of amphibians.

FIRST LIFE ON LANDUntil about 450 million years ago, nothing lived onland. Then, tiny living things, called algae, began tobe washed ashore during low tides. Land plantsprobably adapted over time. They developed waxyskin to stay moist and grew roots to fix themselvesin the ground. By the late Ordovician period, plantswere thriving on land.These plants became food for some marine

creatures that managed to clamber ashore:arthropods. Their shells kept them wet and theirjointed legs were good on the uneven ground.Spiders and insects were the first land dwellers.

Instead ofteethinside itsjaws, Dunkleostus hadrazor-sharp plates ofbone. They couldslice through itsprey likeblades.

11



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12 13

Coal Swamps

BY THE BEGINNING of the Carboniferousperiod, plants had spread across the world’scontinents. Giant trees, such as Lepidendron

(club moss) and Calamites (a large horsetail) filled thehot, steamy jungle swamps. Here, trees grew, died,and rotted. The dead matter eventually turned into adense, dark soil called peat. Over millions of years,these beds of peat became squashed under other soillayers and became rock. Today, we call this rock coal.

In North America300 million yearsago, a group ofEryops, 6-ft- (2 m)long amphibians,wade ashore in thecoal swamp. Theseheavy creaturesprobably spentmost of their timein the water.

Hylonomus, or “forest mouse,”looks down on Eryops.

Diplocaulus

Millipede

Eryops

Dragonfly

Eryops

Hylonomus

In the coal swamps, dragonflies were the size of pigeons. Giantcockroaches and 6-foot- (2 m) long millipedes lived among the trees.Lurking in the waters were the first amphibians. Ichthyostega had a fish-like head and tail. It could crawl ashore to feed, but it still laid its eggs inwater. Over millions of years, some amphibians became able toreproduce on land. They did not need to return to the water. These werethe first reptiles. Hylonomus, an 8-inch- (20 cm) long, lizard-likecreature, was one of them. It adapted to life on land by laying hard-shelled eggs.



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14

Permian Wor ld

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DURING the Permian period, there wasjust one large area of land: the “super-continent” of Pangaea. The southern

parts of Pangaea, at the South Pole, were coveredby a massive ice cap. Much of Earth’s water wasfrozen in this ice, while the rest of the world’sclimate became very hot and dry. The hot, steamyjungles of the Carboniferous period were nowvast scrublands and deserts. Large amphibiansthat depended on water for their jelly-like eggsstarted to die out. Reptiles, which laid their eggson dry land, multiplied. They also developed

powerful jaws, perfectfor eating toughdesert plants.

GIANT SAILSSynapsid reptiles wereancestors of mammals.The earliest group werecalled pelycosaurs.Some were giants withhuge sails on theirbacks, like Dimetrodonand Edaphosaurus.These sails were madeof skin held up by long,thin spines along theanimals’ back. Scientiststhink the sails kept theirbodies at the righttemperature, warmingthem up in the sun andcooling them off whenthey were too hot.

Three types of land reptiles ruled the dry Permianworld. Anapsids (ancestors of tortoises andturtles) had a solid skull. Synapsids (ancestors of mammals) had one hole on each side of theirskull. Diapsids had two holes on each side. Thisgroup were the ancestors of lizards, snakes, andcrocodiles — and dinosaurs.

SLOW MOVERSAfter pelycosaurs camelumbering animals likeMoschops andScutosaurus. Diapsids, like Protorosaurus andCoelurosauravus, werestill rare.

In the late Permian, therewere many large synapsids,but diapsids were on the rise.

Dimetrodon Varanosaurus

Protorosaurus

Moschops

Scutosaurus

Ophiacodon

Edaphosaurus

Coelurosauravus

Dimetrodon, a pelycosaur,basks in the sun.



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16 17

Reptiles of Land, Sea, and Air

IN THE EARLY TRIASSIC PERIOD, a largenumber of sea and land animals becameextinct. Scientists are not sure why this

happened, though the extreme hot and dryclimate across Pangaea could have been thecause. But some reptiles survived, includingthe mammal-like ones, such as Lystrosaurus, apig-like reptile with tusks. Another group, thearchosaurs, quickly multiplied. Atfirst they had a low,sprawling gait, likelizards. Eventually,some of theseanimals began towalk more upright.The powerful runnerOrnithosuchus, for example, had a short body with strong hind legs anda long balancing tail. By the late Triassic, some archosaurs were walkingon two legs all the time. They were the first dinosaurs.

Thrinaxodon (left) was acynodant, a mammal-likereptile about the size of acat. Like a mammal, itdigested food quickly, whichraised its body temperature.Its fur coat kept this heat in.But its skeleton was like areptile’s and it laid eggs.

Placodus ate shellfish from the seabed, but itslegs, feet, and claws were more useful on land.Nothosaurus had a long, slim body, and webbedhands and feet, perfect for swimming.

Nothosaurus

Placodus

For the next 165 million years, dinosaursruled the land, while other kinds of reptilesdominated the sea and air. Themarine reptiles were quite similarto dinosaurs. They had large eyes,sharp teeth, four limbs, and a tail. Butinstead of legs, they had flippers forswimming. The first marine reptiles, likePlacodus and Nothosaurus (below),waddled around on land, but spent time inwater diving for food. Over millions ofyears, new kinds evolved that lived in waterall of the time (see pages 26-31).

Thrinaxodon

ALMOST A DINOSAUREuparkeria was a smallarchosaur with a slim body,a long tail, and long hindlegs. Although it walked onall fours, it probably ran ontwo legs. It had needle-liketeeth and liked to eatinsects and small animalson the forest floor.

Euparkeria

Eudimorphodon

HIGH FLIERSAnother group of archosaurscould fly. They were calledpterosaurs and included therhamphorynchs and thepterodactyls (see pages 20-25).Eudimorphodon was one of thefirst pterosaurs. Its wings weresheets of skin stretching fromits legs to its long fourth finger.



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These groups were definedby the shape and positionof the hip bones. Anornithischian’s

pubic bone(above) slantedbackwards. The pubicbone of a saurischian(right) pointed forwards.

19

TWO DINOSAUR GROUPSHundreds of dinosaur species lived on Earth. There were two groups:saurischians (“lizard-hipped”) andornithischians (“bird-hipped”). Therewere two kinds of saurischians: meat-eating, bipedal (two-legged) theropods,and the plant-eating sauropodomorphs,which walked on either two or four legs.

Pubicbone

Ischium

Pubic bone

SAURISCHIANS ORNITHISCHIANS

Most Sauropodomorphs had long necksand tails. Prosauropods (1) were once

thought to be thebipedal ancestors of

four-legged sauropods(2), but they are now

considered separate groups.Thetheropods

were thefirst dinosaurs to

evolve. Their upright stance gave themthe advantage of speed over otherreptiles. The theropods were made up ofceratosaurs and tetanurans: long-clawedtherizinosaurs (3), raptors (4), huge

tyrannosaurs (5), andornithomimids (6).

Ischium

Thyreophoran dinosaurs included thestegosaurs (7), which had rows of plates or

spines along their backs,and the ankylosaurs (8),which had armoredbodies.

The scelidosaurs, a third group, mayhave been ancestorsto both.

Pachycephalosaurians(9) were bipedal withthick skulls.

The ceratopsians (10)were large, four-legged dinosaurs withhorns and neck frills.

The first ornithopodswere small, bipedalhypsilophodonts. Laterkinds included thelarger iguanodonts (11)and the hadrosaurs or“duckbills.” (12)

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The Dinosaurs

Allosaurus

Archaeopteryx

Dinosaurs from differentcontinents in the Jurassic ageDiplodocus

Compsognathus

DINOSAURS were land reptilesthat lived in tropical habitatsin the Triassic, Jurassic,

and Cretaceous periods. Walkingupright on two or four legs, most hadlong tails and scaly skin, but some hadfeathers. Some were as small as a duckwhile others were 75-ton (68 t) giants.

Stegosaurus

Other reptiles, likethe Komododragon (left),walk with

their legs splayed to the side.Dinosaurs stood uprightwith their legs beneaththeir bodies. Some, like ,Compsognathus (right),could run very fast.

21

Dimorphodon most likely walkedupright, like a bird, with its legsunder itsbody. It couldalso run faston its toes.

“BEAK SNOUT”The name Rhamphorhynchus means “beaksnout.” The earliest-known pterosaurs werealready advanced fliers by the Late Triassicperiod, 210 million years ago. Earlypterosaurs from the Triassic and Jurassicperiods had longer tails and shorter necks thanlater pterosaurs.

CLIFF HANGERRhamphorhynchus had a fifth toe and sharp claws,perfect for grasping branches and rocks. Thissuggested that it was probably anexpert climber. When itwas taking a rest fromflying, it most likelyspent its time hangingfrom cliffs. On theground, the animalwould have folded itswings, like birds and batsdo today, and walked aroundon its tiny legs.

Batrachognathus, or “frog jaw,”(above) had jaws lined with peg-like teeth. It was quick enough to

catchdragonflies inflight. Its smallsize and shorttail would havehelped it tochase afterthem.

PUFFIN HEADDimorphodon (right) had agiant head that was deepand narrow like a puffin’s.Males had coloredbeaks to impressfemales duringmating rituals.

Rhamphorhynchushad a 3-ft (1 m)wingspan.

To catch its prey, Rhamphorhynchus flew lowover rivers and seas, dragging its beak in thewater like a scoop. Once it caught a fish, it

tossed it into its throat pouch like a pelicanwould today. Its teeth pointed

forward and outward,forming a cage to

hold its prey.

Rhamphorhynchus

RHAMPHORHYNCHUSwas an early pterosaur.It had a small, furry

body. Its wings were made ofskin stretched between its longfourth finger and its back legs. Its long,stiff tail had a diamond-shaped tip. Insideits long, narrow jaws were sharp teeth,great for snatching frogs, fish, and bugs.

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ram-fo-RINK-us Late Jurassic Europe and Africa, 150 mil lion years ago

Rhamphorhynchus had huge eyesockets, so its eyes were probably verylarge. With such good eyesight, itcould have spotted prey on land or atsea from high up in the air.



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PTERANODON was a pterosaurfrom the pterodactyl group. It had afurry body and a very short tail. Like

other pterosaurs, its wings were made ofskin stretching from its long fourth fingerto its short back legs just above itswebbed feet. It had a large, backward-pointing, bony crest on its skull. Pteranodon lived on coasts and fed on

fish it spotted from far awaywith its superb eyesight. Itslong wings were kept stiffby long fibers insidethe skin. These werecalled actinofibrils.

Pteranodon fossils have beenfound close together ingroups, some with small

crests, others withlarge ones. Thesmaller-crestedreptiles wereprobablyfemales.

Pteranodon probably ate like apelican does today: it scooped upfish from the water’s surface in itslong, narrow jaws and storedthem in its throat pouch.

22

MISTAKEN IDENTITYThe name Pteranodon means “wings and noteeth.” Pteranodon is often mistakenly called“pterodactyl” but there is not actually ananimal that goes by this name. It is just ageneral name for all short-tailed pterosaurs.Pteranodon was the largest-known pterosaurfrom the time it was first discovered in 1870until 1975, when Quetzalcoatlus, an evenbigger pterosaur, was found.

WHAT’S THE CREST FOR?No one really knows. It is possible that ithelped keep the animal stable as it flew, or wasused for steering or slowing down in flight.Pteranodon’s head was large, so it could haveacted as a counterweight to balance the heavyskull. It may also have been used by males,which probably had bigger crests than females,to impress mates during courtship, or to scarerival males away.

Pteranodon longiceps hada wingspan of 23 ft (7 m).

ter-AN-uh-don

23

Pteranodon

Pteranodon’s long wingswere perfect for gliding onocean air currents, just asan albatross does today. Itcould travel for mileswithout flappingits wings.

Late Cretaceous Europe and North America, 90-70 mil lion years ago

Pteranodonsternbergi

Ornithocheirus (above) was possiblythe largest flying creature of alltime. With a wingspan of up to 40 ft (12 m), it lived off the coasts ofEurope and South America about125 million years ago. It had aunique “keel” at the end of itstoothed beak, useful fortrapping fish.

Pteranodon’swingspancould be up to30 ft (9 m).



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Huanhepterus (above) had aset of teeth like a sieve. It tookwater in its mouth andstrained tiny creatures from it.

MINI SCAVENGERPterodactylus (left)had a wingspan of 2to 3 feet (61 cm—1 m)wide. Its tiny pointedteeth were good forchewing fish. Crawlingaround on all fours onland, it alsoscavenged meat fromother animals’ kills.

24

kwet-suhl-kuh-WAT-lus

Quetzalcoatlus’s wingswere 35 ft (11 m) wide. Tapejara

Tupuxuara

Both Tapejara and Tupuxuarahad sail-shaped head crests madeof skin and held up by bone.These crests were probably usedin displays to attract a mate.

25

Pterodaustro’s lower jaw (above)had hundreds of bristles, goodfor strainingtiny animalsfrom thewater.

Late Cretaceous North America, 75-65 mil lion years ago

A TALL SNAKE GODQuetzalcoatlus was named after the Aztecs’feathered snake god, Quetzalcoatl. When itstood up, it was 18 feet (5 m) tall, about theheight of a giraffe today. Quetzalcoatlus mayhave lived like a vulture, eating carcasses leftbehind by other carnivorous animals.

Gliding over thesea, it may haveused its long,slim jaws to pluck fishfrom the water’ssurface, as a herondoes today. It lacked the muscle

power to take off byrunning quickly. Instead it

may have taken to the air bylaunching itself from acliff edge.

For its huge size,its skeleton was extremelylight. Quetzalcoatlus mayhave weighed only about220 lbs (100 kg).

LIKE otherpterosaurs from thepterodactyl group,

Quetzalcoatlus had a furry body,long narrow wings, a long neck,and a pointed beak. On its headwas a short, bony crest. Itsfavorite foods were fish andshellfish. It also scavenged meatfrom other predators.

Quetza lcoatlus

Dsungaripterus(above) had abony crest onits upward-curving beak.



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26

Ichthyosaurus

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ICHTHYOSAURUSwas a marinereptile. Its body

looked like a dolphin’s. It had aslim, pointed snout with conical teeth,a fish-like tail, and a fin on its back. Itsfront flippers were twice the size of theback ones. Its nostrils were near its eyes,rather than at the tip. Ichthyosaurus livedclose to the surface of the sea, eating fishand shellfish.

Fossils of Ichthyosaurusshow the fingerbones inside itsflippers.

Completefossils, many

in perfect condition,have been discovered.Some are of pregnantmothers. You can see the

bones of their babies inside.

Mixosaurus, 3 ft (1 m) long, and 25-foot (8 m) longShonisaurus were members of the ichthyosaur family.

Ichthyosaurus is one of thefew prehistoric animalswhose fossils show evidence ofskin color. Ichthyosaurus’s skinwas dark red or brown, andwithout scales.

Ammonites, Ichthyosaurus’sfavorite food, were sea creatureswith shells like a snail’s. Relatedto today’s squid and octopuses,they caught their tiny prey withtheir long tentacles.

WATER BABIESThe name Ichthyosaurus means “fishlizard.” Its young were born live. Theycame from their mother tail first, justas whale calves do today. BabyIchthyosauruses could swim rightafter they were born. Fossils showthat most pregnant Ichthyosauruseshad only two babies at a time, thoughthey could have as many as 11.

ik-thee-uh-SAWR-us Early Jurassic Northern seas, 200-190 mil lion years ago

WHAT BIG EYES YOU HAVE!Temnodontosaurus (above) was an ichthyosaur from theEarly Jurassic period. It was a gigantic animal, growingup to 40 feet (12 m) long. Its eyes measured about 8inches (20 cm) across, the largest of anyvertebrate (an animal with a backbone)that ever lived. These eyes wouldhave been its main wayto find prey deepunderwater.

Ichthyosaurus wasabout 6 ft (2 m) long.

Eurhinosaurus’s upper jawwas long and narrow withteeth pointing sideways.



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Plesiosaurus

PLESIOSAURUS was amarine reptile with a longneck, a short tail, and a

small head. It had many cone-shaped teeth. Its nostrils were ontop of its head. It had long,narrow flippers, but no fins. Itsbody was covered with smooth(not scaly) skin. It ate fish, squid,and shellfish in surface waters.

Plesiosaurus’s lower jaw could openvery wide. Its sharp, interlockingteeth were a good fish trap.

Plesiosaurusused its longneck to reachforward andsnatch smallmarinecreatures inits jaws.

Macroplata (above left) lived inshallow seas off the coast of Europeduring the Early Jurassic period. Arelative of Plesiosaurus, it had large,powerful shoulders and a long neck.

Elasmosaurus’s neck was more than halfits total body length.

Paleontologists once thought a plesiosaur’sflippers were like large oars, moving backand forth as it swam. Now scientists thinkthey were more like wings flapping up anddown. The bones in these flippers weremore like a penguin’s or a sea turtle’s,which both “fly” through water.

A SWIMMING LIZARD“Plesiosaurus” means “near lizard.” Itwas given this name to show it was moreclosely related to land reptiles thanmarine reptiles. Its flippers eachcontained five fingers made up of manysmaller bones. It may also have laid eggson land, like sea turtles do today.

FOUND: LOCH NESS MONSTER?Could the Loch Ness Monster—if it existsat all—really be a plesiosaur? Probablynot. First, lakes are too cold for such alarge, cold-blooded animal to survive.Second, plesiosaurs needed to breathe airregularly, which would mean that manymore people would have seen “Nessie.”

A long neck was good for reaching up fromdeep water to catch fish by surprise. It couldalso help a plesiosaur change direction quicklyas it swam while hunting. It probably could notlift its head too far above the water’s surface.Its head and neck were too heavy.

plee-zee-uh-SAWR-us Early Jurassic European seas, 200 mil lion years ago

Plesiosaurus was 15 ft(5 m) long.



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30 31

Kronosaurus

Kronosaurus was 30 ft (9 m) long.

Kronosaurus’ssharp, forward-pointing frontteeth were perfectfor trapping prey.Its back teethwere good forcrushing bonesand shells.

Kronosaurus’s headwas bigger than thatof Tyrannosaurus rex!

Teleosaurus

Geosaurus

Xiphactinus

Archelon

Platecarpus

GREATEST OF ALL TIMEKronosaurus’s name means “lizard ofChronos.” Chronos was the ancientGreek god of time who ate his fivechildren as they were born in order tokeep power for himself. Kronosaurus was probably the

biggest marine reptile that ever lived. It“flew” through the water using its fourpaddle-like flippers, just as sea turtles dotoday. It may also have laid its eggs innests on land as sea turtles do, using itspowerful flippers to drag itself ashore.

Tylosaurus

kroh-nuh-SAWR-us

Some prehistoriccrocodiles spent alltheir lives at sea.Geosaurus even hadflippers and a fish-like tail. Ammonite

LIFE AT SEAMany species adapted to life in the water.Platecarpus and Tylosaurus were bothmosasaurs (sea lizards). Platecarpus atefish and tiny ammonites, but giantTylosaurus had a bigger appetite. Itfought with Xiphactinus over bigger preysuch as large fish, marine reptiles, andsea birds. Archelon was the largest-known sea

turtle, measuring 13 feet (4 m) long. Likea leatherback turtle today, its “shell” wasa bony frame covered with skin.

Mid-Cretaceous Australian seas, 110 mil lion years ago

KRONOSAURUS was a pliosaur (ashort-necked plesiosaur) that livedin warm, shallow Jurassic seas. An

extremely powerful predator, it huntedanything that swam, including othermarine reptiles. Its giant head was about aquarter of its bodylength. It had fourpaddle-like flippersfor swimming and ashort, pointed tail.Its front flipperswere almost aslong as aperson istall.



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IndexPage numbers in bold refer toillustrations

Aactinofibrils 22algae 10Allosaurus 18, 19ammonites 27, 31amphibians, evolution of 11, 12-13

Anhanguera 22ankylosaurians 19Anomalocaris 8, 9Anurognathus 20Archaeopteryx 18Archelon 31archosaurs 16-17arthropods 10Attenborosaurus 28Azhdarcho 24

BCbacteria 9Batrachognathus 20, 21Burgess Shale 9Calamites 13Cambrian period 6, 7, 9"explosion" of life 7, 9

Carboniferous period 6, 12-13, 14ceratopsians 19ceratosaurs 19club moss 13coal swamps 12-13Coelurosauravus 15Compsognathus 18crests (of pterosaurs) 22-25Cretaceous period 6, 18, 22-25, 27, 31

crocodiles 15, 31

DDevonian period 6, 10Dimetrodon 14Dimorphodon 20, 21dinosaurs 31evolution of 15, 16-17, 18-19extinction of 31features of 18-19ornithischian 19saurischian 19types of 19

Diplocaulus 12Diplodocus 18dragonflies, giant 12, 13Dsungaripterus 25Dunkleostus 10

EEarth 6-7atmosphere 7movements 6origins 7

Edaphosaurus 14egg laying 13, 14, 16Elasmosaurus 28, 29Eryops 12, 13Eudimorphodon 17, 20Euparkeria 16Eurhinosaurus 26, 27eurypterids 10Eusthenopteron 11extinctions 16, 31

FGHfish, early 10-11evolution of 10-11lobefin 11

geological time 6-7Geosaurus 31hadrosaurs 19Hallucigenia 8, 9Hatzegopteryx 24horsetail 13Huanhepterus 24Hylonomus 13hypsilophodonts 19

IJKichthyosaurs 17, 26-27Ichthyosaurus 26-27, 29Ichthyostega 13iguanodonts 19insects 10Istiodactylus 22jellyfish 8Jurassic period 6, 18, 20-21, 26- 27, 30

Komodo dragon 18Kronosaurus 30, 31

LLeanchoilia 9Lepidendron 13life, earliest 8-9marine 8-9, 10, 17, 26-31emerges on land 10-11

Liopleurodon 26, 30lizards 15, 18, 31Loch Ness Monster 29lycopod 13Lystrosaurus 16

MNMacroplata 28mammals, evolution of 14Mesosaurus 14millipedes, giant 12, 13Mixosaurus 26Montanazhdarco 24Moschops 15mosasaurs 17, 31Muraenosaurus 28Nothosaurus 17Nyctosaurus 22

Ooceans 7, 8Opabinia 9Ophiacodon 14Ophthalmosaurus 26Ordovician period 6, 10ornithischians 19Ornithocheirus 22, 23ornithomimids 19ornithopods 19Ornithosuchus 16

Ppachycephalosaurians 19Pangaea 14peat 12pelycosaurs 14-15Permian period 6, 14-15, 16Phosphatodraco 24 Pikaia 9Pistosaurus 28Placodus 17plants, evolution of 10, 12-13Platecarpus 31plesiosaurs 17, 28-29Plesiosaurus 28, 29pliosaurs 17, 26, 30-31Pliosaurus 30Precambrian 6-7prosauropods 19Protorosaurus 15Pteranodon 17, 22-23pterodactyls 17, 22-25Pterodactylus 24Pterodaustro 25pteroid 22pterosaurs 17, 20-25

QRQuaternary 6Quetzalcoatlus 17, 23, 24, 25raptors 19

reptiles, anapsid 15diapsid 15, 16evolution of 13, 16-17flying 17mammal-like 14, 16marine 14, 17, 26-31synapsid 14-15temperature regulation in 14therapsid 15

rhamphorhynchs 17, 20-21Rhamphorhynchus 20-21

SSanctacaris 9saurischians 19sauropodomorphs 19sauropods 19Scaphognathus 20scelidosaurs 19Scutosaurus 15Shonisaurus 26Silurian period 6, 10Simolestes 30snakes 15Sordes 20spiders 10stegosaurs 19Stegosaurus 18

TTapejara 15Teleosaurus 31Temnodontosaurus 26, 27Tertiary period 6tetanurans 19Thalassomedon 28therizinosaurs 19theropods 19Thrinaxodon 16thyreophorans 19tortoises 15trees, evolution of 12-13Triassic period 6, 16-17, 18trilobites 9, 10Tupuxuara 25turtles 15, 30-31Tylosaurus 31tyrannosaurs 19

VWXZVaranosaurus 14vertebrates 9Wiwaxia 8, 9Xiphactinus 31Zhejiangpterus 24


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