Which statement explains why ammonites are a good example of an index fossil.

Question

Which statement explains why ammonites are a good example of an index fossil.

Ammonites existed in a small geographic area
Ammonites existed for a relatively limited period of time
Ammonites existed only in the oceans
Ammonites existed long before the dinosaurs

Answer 1

The statement "Ammonites existed for a relatively limited period of time" explains why ammonites are a good example of an index fossil.

Answer 2

The statement that explains why ammonites are a good example of an index fossil is:

"Ammonites existed for a relatively limited period of time."

Index fossils are used by paleontologists to date and correlate rock layers. They are organisms that were widespread geographically and existed for a relatively short period of time. Ammonites fit these criteria as they were abundant and diverse during the Mesozoic Era, particularly during the Jurassic and Cretaceous periods, but became extinct at the end of the Cretaceous, about 66 million years ago.

Answer 3

The statement "Ammonites existed for a relatively limited period of time" explains why ammonites are a good example of an index fossil. Index fossils are used in geology to determine the relative age of rock layers. They are species that existed for a short period of time but were widespread. This allows scientists to correlate rock layers from different locations that contain the same index fossil. In the case of ammonites, they existed during the Mesozoic Era, from approximately 240 million to 65 million years ago. This relatively short time span makes them a useful indicator of the age of the rocks in which they are found.