Using the principle of faunal succession, if an unidentified fossil is found in the same rock layer as an index fossil, the two species must have existed during the same period of time (Figure 4).

Using the principle of faunal succession, if an unidentified fossil is found in the same rock layer as an index fossil, the two species must have existed during the same period of time (Figure 4).

The Role of Stratigraphy in Dating Fossils Stratigraphy involves studying rock layers (strata) to determine the relative ages ...

The situation on land is far hazier. Only a handful of places around the world have rock layers containing fossils from land ecosystems at the end of the Permian and beginning of the Triassic.