Chalicotheres (from Greek chalix, "gravel" and therion, "beast") are an extinct clade of herbivorous, odd-toed ungulate (perissodactyl) mammals that lived in North America, Eurasia, and Africa from the Middle Eocene until the Early Pleistocene, existing from 46.2 mya to 781,000 years ago. They are one of the five major radiations of perissodactyls, with three groups living (horses, plus the extinct paleotheres; rhinoceroses; tapirs), and two extinct (brontotheres and chalicotheres).