The paleocene epoch left a thin layer of rock that is extremely rich in fossils.

1.fish
2.mammal
3.fern
4.none of the above

Mammal

The Paleocene epoch was ruled primarily by mammals. By this time period, dinosaurs were found in water bodies and large aviary creatures also existed. Due to the climate shifts, these organisms were spread throughout the globe. 

Mammals began to become more abundant during this epoch, which means that by the time this epoch ended, the mammals died and their fossils occupied the top layer of the soil.

The answer is texture