Studying Fossils

It's All In The Rocks

Authors: JoAnne Dombrowski and Aleta Sullivan
Woodrow Wilson Biology Institute

Target age or
ability group:
Middle School Science and High School Biology
Class time
One 55 minute class period.
Materials and
Student Handouts
Summary of
Students think critically to determine fact or inference when examining sedimentary layers with embedded fossils. This lesson could be used as an introduction to geology as well as in evolutionary biology.
concepts or
necessary to
complete activity:
Geology Paleontology Sedimentary Rock Formation Fossil Formation
Teacher Instructions Place students in cooperative groups, allowing them to interact and complete the activity.
Answers to Part A:Facts: 1, 3, 7
Answers to Part B:Facts: 1, 4
Ask the students individually to write a story about either diagram and share the stories as time permits.

It's All In The Rocks

Part A- Stories In The Bones

Paleontologists, archaeologists and other scientists digging into the past base conclusions about their finds on partial evidence. They have to be able to tell the difference between a fact and an inference. Here's your chance to practice scientific reasoning. Suppose you are in charge of a group of paleontologists digging at a fossil site. Someone screams "Eureka!" When you go over to investigate, you observe the fossilized bones pictured in Diagram A. Based upon your observations of the bones, which of these statements is a fact and which is an inference?




1.The fossil find includes a jaw bone.

2.The person who screamed "Eureka" uncovered a fossil find.

3. This animal had sharp, dagger-like teeth.

4. This animal ate other animals.

5. This animal used its sharp claws to kill prey.

6. This animal walked on land.

7. This animal was a vertebrate.

8. This animal had fur or other body covering to keep warm.

Part B- Stories in the Rocks

Geologists and paleontologists rely on what they find in rocks to confirm their theories. But rocks can't talk, so sometimes the conclusions must be inferred.

Examine the rock sample shown in Diagram B. It was removed from the ground exactly as illustrated (the top portion of the rock was nearest the surface). Classify each of the following statements as an inference or a fact.




1. The rock sample has seven layers.

2.The oldest layer is found at the bottom.

3. The youngest layer is found at the top.

4. This sample is a sedimentary (or layered) rock type.

5. Dinosaurs probably existed when these fossilized organisms were alive.


What events could alter this rock arrangement? How might the changes confuse our study?

On to Where Should We Place Archaeopteryx
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