Among the scanty mammals of the Lower Eocene formation we have the perissodactyle Ungulata represented by Coryphodon, Hyracotherium, and Pliolophus.

The Coryphodon appears to have been allied to the Miocene and later Tapirs, while Pliolophus, in its skull and dentition, curiously partakes of both artiodactyle and perissodactyle characters; the third trochanter upon its femur, and its three-toed hind foot, however, appear definitely to fix its position in the latter division.