A Chalicotheres.
Chalicotheres (from Greek chalix, "gravel" + therion, "beast") were a group of herbivorous, odd-toed ungulate (perissodactyl) mammals spread throughout North America, Europe, Asia, and Africa during the Early Eocene to Late Pliocene subepochs living from 55.8 mya—3.5 million years ago, existing for approximately 55.02 million years.[not in citation given]
They evolved around 40 million years ago from small, forest animals similar to the early horses. Many chalicotheres, including such animals as Moropus and Chalicotherium, reached the size of a horse. By the late Oligocene, they had divided into two groups: one that grazed in open areas and another that was more adapted to woodlands. They died out around 3.5 million years ago. They are related to the extinct brontotheres, as well as to modern day horses, rhinoceroses, and tapirs.