Prehistoric Animals
Extinct Animals
Fossils

How do you know how old a fossil is?

Answer

Wiki User
03/29/2014

Fossils are dated based on the layer of rock they are found in. They can be dated relatively, by comparing them to the ages of layers that are above and below. The rock layer could be dated by using radiometric dating. Also, index fossils (widespread organisms that existed for a short period of time) can be used to date a rock layer.