Index Fossils and Their Significance

The video tutorial explains how to identify index fossils, which are used to define geologic periods. Two criteria must be met for a fossil to be considered an index fossil: it must be found in only one type of rock layer and be abundant. The tutorial provides examples of analyzing different fossils to determine if they meet these criteria. Students are instructed to work through their diagrams, identifying index fossils by circling them or marking a box.

What is the primary purpose of index fossils?

• To measure the size of fossils

• To find the depth of fossils

• To determine the color of rocks

• To identify the age of rock layers

Which of the following is a criterion for a fossil to be an index fossil?

• It must be the largest fossil in the layer

• It must be the oldest fossil in the layer

• It must be found in only one type of rock layer

• It must be found in multiple rock layers

What is the first step in determining if a fossil is an index fossil?

• Check if it is found in only one type of rock layer

• Check if it is the most colorful fossil

• Check if it is the oldest fossil

• Check if it is the largest fossil

Why is it important for an index fossil to be abundant?

• To verify it is the only fossil in the layer

• To confirm it lived for a long period

• To prove it is the most colorful fossil

• To ensure it is easily found in multiple locations

What is the significance of finding multiple fossils of the same type in a layer?

• It means the fossils are the largest in the layer

• It suggests the fossils are from different periods

• It indicates the fossils are not index fossils

• It confirms the fossils are abundant

In the diagram, why is the gray fossil not considered an index fossil?

• It is found in multiple rock layers

• It is not abundant in its layer

• It is the smallest fossil

• It is not a fossil at all

What makes the orange fossil in the diagram an index fossil?

• It is the oldest fossil

• It is abundant and found in one layer

• It is found in multiple layers

• It is the most colorful fossil

Why is the yellow fossil not an index fossil?

• It is the most colorful fossil

• It is not abundant

• It is the largest fossil

• It is found in two types of rock

What should students do once they identify an index fossil in their diagram?

• Remove it from the diagram

• Circle it or mark it in the box

• Color it differently

• Ignore it

What should students do after completing their diagram analysis?

• Continue with the activity

• Start a new diagram

• Submit their work

• Erase their marks