Teams of scientists are
digging fossils at each of the
four locations shown in the
diagram. How are the index
fossils useful to the
scientists?
![Teams of scientists are digging fossils at each of the four locations shown in the diagram How are the index fossils useful to the scientists class=](https://us-static.z-dn.net/files/db4/3dbb1c3118e8044065cdff304b10f564.png)