Chalicotheres (from Greek chalix, gravel + therion, beast) were a group of herbivorous, odd-toed ungulates (perissodactyl) mammals spread throughout North America, Europe, Asia, and Africa during the Early Eocene to Early Pleistocene subepochs living from 55.8 mya—781,000 years ago, existing for approximately . 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 t… (More on Chalicothere)