Index Fossils Pre-Flashcard

Front

What are the two main traits of the best index fossils?

Back

Widespread geographically and short lifespan.

Front

What is one of the oldest organisms discovered?

Back

Trilobite.

Front

Which fossil is considered the best index fossil?

Back

Fossil 2.

Front

According to the law of superposition, where are the oldest fossils found?

Back

Near the bottom of the rock layers.

Front

What can we say about all of the fossil 2s?

Back

They are all about the same age.

Front

Define index fossil.

Back

A fossil that is used to define and identify a particular time period in the geological time scale.

Front

What is the significance of widespread distribution in index fossils?

Back

It indicates that the organism lived in many places, helping to correlate the age of rock layers.

Front

Why is a short lifespan important for index fossils?

Back

It allows for precise dating of the rock layers in which they are found.

Front

What does the law of superposition state?

Back

In undisturbed rock layers, the oldest layers are at the bottom and the youngest are at the top.

Front

Give an example of an index fossil.

Back

Trilobite.