Fossils themselves, and the sedimentary rocks they are found in, are very difficult to date directly. Instead, other methods are used to work out a fossils age. These include radiometric dating of volcanic layers above or below the fossils or by comparisons to similar rocks and fossils of known ages.

Is it a rock or fossil?

Fossils are not the remains of the organism itself! They are rocks. A fossil can preserve an entire organism or just part of one. Bones, shells, feathers, and leaves can all become fossils.