Crayfish lived in the shallow, near-shore water of Fossil Lake. Procambarus is known only from the Eocene deposits of Fossil Lake. Its closest living relative, Austrocambarus, is found in Mexico. National Park Service photo.
Armadillosuchus, a crocodyliform which lived in the late cretaceous period. Armadillosuchus and the family it belongs to, Sphagesaurid, were very mammal-like. Armadillosuchus is believed to be not only terrestrial, but possibly have a fossorial lifestyle.