4 Fossil Detectives

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Scott Foresman Science 4.8

Genre Comprehension Skill Text Features Science Content

Nonfiction Summarize • Captions

• Labels

• Text Boxes

• Glossary

Rocks and

Minerals

ISBN 0-328-13882-7

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Extended Vocabulary

anatomy

Cretaceous

extinct

Jurassic

paleontologyprotruding

quarry

Vocabulary

igneous rock

luster

metamorphic rock

mineral

sedimentsedimentary rock

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ISBN: 0-328-13882-7

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

by Joyce A. Churchill



2

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 figure 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 reflects from the surface of rocks. A mineral’shardness 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 rockigneous 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 belowEarth’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. Scientistsmust be good

detectives to find

and figure out

the clues.

fossil of a

dinosaur footprint



4

Layers of CluesDo you like to spend hours solving riddles, playing

games, and fitting 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 andreptiles 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 first 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 figured out what some dinosaurs looked

like and how they lived. But before they can figure all

that out, they first have to find the pieces and put

them together!

fossilized fish

How a Fossil Is Formed

After millions ofyears of erosion andweathering, thebones appear at thesurface. They pokethrough the soil,where they arediscovered.

The hard parts of theanimal, such as thebones, are preservedin the layers. Eggs,skin, and evenfootprints of dinosaursharden as they slowlybecome fossils.

Fossils are theremains of plantsand animals thatonce lived. When adinosaur died, itsbody was slowlycovered by layers ofsedimentary rock.



6

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 identified 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 flippers and a long jaw with sharp teeth.

This was the first 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 findings. Finally, after

Anning’s many years of hard work, they recognized

the importance of her discoveries.

Tools for Fossil HuntingUncovering 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

brushpick



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 find

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 foundwas linked to the Iguanodon, a large,

plant-eating dinosaur.

Gideon Mantell

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 field 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 finds

Othniel Charles Marsh

Keeping Records



10

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 find 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 find, document,and name new species. This was called the Bone War.

Edward Drinker Cope

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,

first 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-storybuilding!

Werner Janensch

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



12

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 field 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 YorkCity, where Brown was the curator for many years.

Barnum Brown

Barnum Brown

Barnum Brown supervised the

assembly of many dinosaur

skeletons.

13

Brown discovered his first 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 first

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 fifteen and twenty feet tall

and almost forty feet long. It weighed

between five 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, extinctreptile 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



14

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 first 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 theirparents, 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 thecomplete 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.



16

Glossaryanatomy the science of the parts of living things

Cretaceous a period of time at the end of

the Mesozoic era that ended

66.4 million years ago

extinct no longer existing

Jurassic a period of time in the middle of the

Mesozoic era when dinosaurs lived

paleontology the science of studying fossils

protruding sticking out from its surroundings

quarry a place where stone is dug, cut,

or blasted out

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?

4. The people in this

book enjoyed the study of fossils. Explain

on your own paper why you think

someone would want to become apaleontologist. 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?

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4 Fossil Detectives