If a fossil cannot be dated directly, how is its age typically bracketed using absolute dating methods?

Answer

By applying absolute dating techniques to igneous rock layers immediately above or below the fossil-bearing layer.

Fossils themselves are often too altered for direct absolute dating, so scientists date associated, datable igneous layers to establish an age range that encompasses the fossil.

If a fossil cannot be dated directly, how is its age typically bracketed using absolute dating methods?
Geologyrockfossilpreservationlayer