Their bones also were frequently found in association with our human and primate ancestors.
In the past, relative dating methods often were the only ones available to paleoanthropologists.
As a result, it was difficult to chronologically compare fossils from different parts of the world.
However, the assumption of contemporaneity may not always be correct.
This is due to the fact that one or both of the objects may have been moved or redeposited into a different location.