4 8 fossil detectives (earth science)

Scott Foresman/Dorling Kindersley would also like to thank: 9 BR Natural History Museum, London/DK Images; 15 TR Natural History Museum, London/DK Images.. Three kinds of rock have been

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Scott Foresman Science 4.8

Nonfi ction Summarize • Captions

• Labels

• Text Boxes

• Glossary

Rocks and Minerals

ISBN 0-328-13882-7 ì<(sk$m)=bdiicb< +^-Ä-U-Ä-U

Scott Foresman Science 4.8

Nonfi ction Summarize • Captions

• Labels

• Text Boxes

• Glossary

Rocks and Minerals

ISBN 0-328-13882-7 ì<(sk$m)=bdiicb< +^-Ä-U-Ä-U

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1 How is a fossil formed?

2 What is Mary Anning famous

for discovering?

3 What led to the feud between Othniel

Charles Marsh and Edward Drinker Cope?

book enjoyed the study of fossils Explain

on your own paper why you think someone would want to become a paleontologist Include details from the book to support your answer

5 Summarize Write a brief summary of

the life and work of Barnum Brown

What did you learn?

Extended Vocabulary

anatomy Cretaceous extinct Jurassic paleontology protruding quarry

Vocabulary

igneous rock

luster

metamorphic rock

mineral

sediment

sedimentary rock

Picture Credits

Every effort has been made to secure permission and provide appropriate credit for photographic material

The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.

Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).

4 Richard T Nowitz/Corbis; 6 (CR) ©The Natural History Museum, London; 8 (TR) Photo Researchers, Inc.;

12 (T, B) Bettmann/Corbis; 14 (TR) ©The Natural History Museum, London.

Scott Foresman/Dorling Kindersley would also like to thank: 9 (BR) Natural History Museum, London/DK Images;

15 (TR) Natural History Museum, London/DK Images.

ISBN: 0-328-13882-7

This publication is protected by Copyright, and permission should be obtained from the publisher prior to any

prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,

mechanical, photocopying, recording, or likewise For information regarding permission(s), write to

Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05

by Joyce A Churchill

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You can learn a great deal about Earth, and the

plants and animals that live on it, from rocks Rocks can

form both above and below the surface of Earth They

form in many layers By studying the different layers,

scientists can fi gure out Earth’s past and present

Minerals, which are natural, nonliving crystals,

combine to form rocks Scientists can identify

rock-forming minerals through their properties Color

and luster are properties of minerals that relate to the

way light refl ects from the surface of rocks A mineral’s

hardness is measured by how easily it can be scratched

The color of the powder that the mineral leaves behind

after being scratched is another property called streak

Three kinds of rock have been found on Earth:

igneous, metamorphic, and sedimentary All three kinds

can change from one to another over time This process

is called the rock cycle

sedimentary rock igneous rock metamorphic rock

What You Already Know

3

Igneous rocks form from molten (melted) or partly molten rock deep below Earth’s surface Rock is melted

by the intense heat that causes volcanic eruptions Dead plant and animal matter combines with bits of rock to form soil, which settles on the bottoms of lakes, rivers, and oceans This is called sediment This material can

be moved by water, ice, wind, or gravity to form layers

These layers press together and become sedimentary rock Metamorphic rock can form from any kind of rock as a result of heat and pressure deep below Earth’s surface

Fossils in sedimentary rock give scientists clues to what lived on Earth hundreds of millions of years ago

Fossils are the bones, teeth, leaves, or any evidence

of a living thing from long ago Scientists must be good detectives to fi nd and fi gure out the clues

fossil of a dinosaur footprint

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Layers of Clues

Do you like to spend hours solving riddles, playing

games, and fi tting together puzzles? Then you might want

to become a paleontologist You would be a scientist who

studies fossils to discover what Earth was like long ago

You would be a fossil detective!

Paleontologists search for the answers to many

questions What creatures lived on Earth? What did they

eat? Were these creatures mammals? Were they reptiles?

Were they birds? Why did they disappear? The list of

questions goes on and on

Over the past 200 years, fossil detectives have

answered some of these questions Giant birds and

reptiles that we now call dinosaurs lived from 65 million

to over 200 million years ago Scientists know that these

strange creatures lived on each of Earth’s continents

A paleontologist searches for fossils.

5

Scientists have developed

a geologic time scale to study fossils in the layers and layers

of sedimentary rock They agree that dinosaurs fi rst appeared, lived, and then disappeared during the Mesozoic era on their scale This is the middle period in the history of Earth

Using pieces of skeletons and other fossils as clues, scientists have fi gured out what some dinosaurs looked like and how they lived But before they can fi gure all that out, they fi rst have to fi nd the pieces and put them together!

fossilized fi sh

How a Fossil Is Formed

After millions of years of erosion and weathering, the bones appear at the surface They poke through the soil, where they are discovered

The hard parts of the animal, such as the bones, are preserved

in the layers Eggs, skin, and even footprints of dinosaurs harden as they slowly become fossils

Fossils are the remains of plants and animals that once lived When a dinosaur died, its body was slowly covered by layers of sedimentary rock

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You might not think of a young,

uneducated girl as being an important

dinosaur fossil collector, but Mary

Anning was one Anning, born in 1799,

and her brother collected fossils with

their father After his death, they

continued scouring the cliffs near their

home in Lyme Regis in southern England They sold

the fossils they found to help support the family

Paleontology Pioneers

Mary Anning

Before the 1800s, a few large fossil bones were

found sticking out of the ground No one knew what

they were from Once scientists identifi ed the fossils as

the remains of dinosaurs, they became fascinated with

these mysterious creatures

Anning and her brother

looking for fossils

Mary Anning

7

Plesiosaurus fossil

When she was twelve years old, Anning uncovered the skeleton of a marine reptile in a cliff She chipped away the rock to reveal four fl ippers and a long jaw with sharp teeth

This was the fi rst Ichthyosaurus ever found, and it was more than thirty-two feet long This was just one of Anning’s many discoveries

The leading scientists of the time did not want

to give Anning credit for her fi ndings Finally, after Anning’s many years of hard work, they recognized the importance of her discoveries

Tools for Fossil Hunting

Uncovering a skeleton embedded in rock takes time and patience The hammer and chisel remove fossils from a rock The pick chips away dirt from a bone The brush dusts away any remaining dirt.

chisel

hammer brush

pick

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Gideon Mantell was a doctor,

but he loved hunting for fossils As a

young boy he hunted for them in the

quarries near his home in Lewes,

Sussex, England

In 1822, he and his wife were

exploring Tilgate Forest, a quarry near their

home They stumbled across a large, fossilized tooth

This was unlike anything the doctor had seen before,

so he took it to several leading paleontologists to fi nd

out what it was One scientist told him that it was a

tooth from a rhinoceros Mantell didn’t believe him

Finally, in 1825, the tooth Mantell found

was linked to the Iguanodon, a large,

plant-eating dinosaur

Gideon Mantell

fossilized

Iguanodon tooth

8

Mantell lecturing

on his discoveries

9

Othniel Charles Marsh was a respected vertebrate paleontologist in the 1800s Marsh was an “armchair paleontologist,” who collected fossils

as a hobby He didn’t like to go into the fi eld to collect the fossils Marsh preferred to quietly sort and catalog

fossils at the Peabody Museum at Yale University, where he worked

His friend Edward Drinker Cope, a younger paleontologist, had proudly assembled the skeleton of the Elasmosaurus,

a giant dinosaur So Marsh went to look at the skeleton He quickly pointed out to Cope where the body parts were mixed up This started a bitter feud between the two men that lasted more than twenty years

Othniel Charles Marsh

Keeping accurate records

of where bones are found is important Paleontologists can match the location of fossils in sedimentary rock with the times that animals lived on the Earth

Marsh discussing his fossil fi nds

Othniel Charles Marsh

Keeping Records

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Edward Drinker Cope was a

hard-working paleontologist who looked for

dinosaur remains He explored in the

western United States between 1870

and 1890

Some of the biggest dinosaur

graveyards are in the western United

States The bones of giant animals such as the Diplodocus,

Stegosaurus, and Triceratops have been found there

In the science of paleontology, if you fi nd a new

dinosaur species, you have the honor of naming it

After Othniel Charles Marsh insulted Cope, they became

enemies They competed in the West to fi nd, document,

and name new species This was called the Bone War

Edward Drinker Cope

Cope used dynamite to blast his

way through to hidden bones.

11

The huge Brachiosaurus, or “arm lizard,” was a giant land animal from the late Jurassic period Werner Janensch, a German paleontologist,

fi rst collected its bones during an expedition to East Africa, in what is now the country of Tanzania, from 1909 to 1913

Janensch shipped tons of bones back to the Natural History Museum of Berlin He and other scientists unpacked the bones and assembled them piece by piece into a giant skeleton Their work was like putting

together a jigsaw puzzle that

is as tall as a four-story building!

Werner Janensch

Fossils have to be chipped out of rocks with great care

The more carefully preserved the fossil is, the more scientists can learn from it

Extracting Fossils

Janensch and workers with a Brachiosaurus bone

removing a fossil

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Barnum Brown was named after

P T Barnum, the nineteenth-century

American showman and circus

founder He began picking up the

fossils of extinct animals as a boy in

Kansas He collected fossils for more

than sixty-six years as a paleontologist

Brown loved working in the fi eld collecting fossils

He searched for dinosaur remains in the United States,

Canada, South America, India, and Ethiopia

Brown discovered the skeletal remains of

Tyrannosaurus rex The T rex was displayed in the

American Museum of Natural History in New York

City, where Brown was the curator for many years

Barnum Brown

Barnum Brown supervised the

assembly of many dinosaur

skeletons

13

Brown discovered his fi rst T rex in 1902 He

then discovered an even better skeleton in 1908

He assembled both in the Museum of Natural History Years later, the fi rst skeleton Brown discovered was moved to the Carnegie Museum

in Pittsburgh, Pennsylvania

The fossils revealed that the T rex

had a huge jaw that helped it devour nearly any food it wanted It was between fi fteen and twenty feet tall and almost forty feet long It weighed between fi ve and seven tons

Barnum Brown also discovered the duck-billed Corythosaurus from the Cretaceous period He found its skeleton

in the Red Deer River in Alberta, Canada

Putting together the skeleton of a giant, extinct reptile such as the Allosaurus

is a challenging job You must know anatomy and the bone structure of similar animals in order to put each part in the right place.

Reconstructing Fossils

Tyrannosaurus rex

reconstructing an Allosaurus skeleton

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John R Horner had trouble in

school as a boy because of a learning

disability Yet he has collected and

cataloged fossils since he was seven

years old

In 1978, he found the fi rst nest of

baby dinosaurs in Montana He named

this new dinosaur the Maiasaura The

babies were about the size of a crow

The next year he found the remains of a herd of

more than ten thousand Maiasaurs He also has found

eggs and more nesting grounds Horner’s discoveries

show that some dinosaurs were cared for by their

parents, instead of having to fend for themselves as

soon as they hatched

John R Horner

model of a Maiasaura nest John R Horner

15

Horner explains that hunting for dinosaur fossils is not a simple or exact science It is not just collecting and organizing fossil bones You have to look carefully at the clues you collect

Then you need to consider many possibilities about how these animals lived

Men and women have been hunting and collecting dinosaur fossils for more than 200 years

Yet they still don’t know the complete history of dinosaurs

They know that these giants once lived on each of the Earth’s

continents They know what some of them looked like and how they lived But they don’t know exactly why they suddenly became extinct

Some scientists say we have only found and collected a small number of the fossilized remains of dinosaurs We don’t know the full story yet We have

to keep digging There is still much work for fossil detectives to do

The Archaeopteryx was both a bird and a reptile.

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Glossary

the Mesozoic era that ended 66.4 million years ago

Mesozoic era when dinosaurs lived

or blasted out