Which statement explains why ammonites are a good example of an index fossil?(1 point)

Question

Responses

Ammonites existed only in the oceans.
Ammonites existed only in the oceans.

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

Ammonites existed long before the dinosaurs.
Ammonites existed long before the dinosaurs.

Ammonites existed in a small geographic area

Answer 1

The statement that best 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 in geology to help date strata and correlate them across different locations. For a fossil to be an effective index fossil, it should have a short vertical range (limited time of existence), be widespread geographically, and be easily identifiable. Ammonites fit these criteria well.