PLEASE HELP!! Which type of fossils are used to identify specific time periods?
A) index fossils
B) all fossils
C) body fossils
D) trace fossils

Index

Explanation:

An index fossil can be used to identify a specific period of time. Organisms that make good index fossils are distinctive, widespread, and lived briefly. Their presence in a rock layer can be used to identify that period of time over a large area.

An index fossil

Explanation:An index fossil can be used to identify a specific period of time. Organisms that make good index fossils are distinctive, widespread, and lived briefly. Their presence in a rock layer can be used to identify that period of time over a large area.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

age range would be the answer