A very difficult science question calling all smart people!!!?

[Albert]

Trilobites are index fossils. Paleontologists find a trilobite fossil in a rock layer at the top of a hill in South America. Then they find the same kind of fossil in a rock layer at the bottom of a cliff in Africa. What could the paleontologist conclude about the two rock layers?

 

[Michelle :P]

The fossils were "made" at the same time.