Question

A scientist wants to determine the age of a rock. The rock contains an index fossil and an ancient relative of a living organism. Which is more useful for dating the rock, and why?

Answer: an ancient relative of a living organism would be more useful for dating the rock because fossils in a rock layer represent what lived during the period the rock was deposited.

Answer 1

I really don't know enough about this topic to help you, but you can compare your answer to the information here:

http://www.nature.com/scitable/knowledge/library/dating-rocks-and-fossils-using-geologic-methods-107924044

Answer 2

For dating a rock, it would be more useful to use index fossils because it indicates the relative age of the rock in which it is found. Index fossils come from species that were widespread but existed for a relatively brief period of time.