Visitor Center diorama, Agate Fossil Beds National Monument, 2016.

Reconstructed skeletons of Miocene age mammals aid in understanding the early 1900s excavations. Mammals found at Agate Fossil Beds National Monument date from the early Miocene Epoch (19-21 million years ago). Scientists describe the Miocene Epoch as the period of time from 5-23 million years ago.