Leptomeryx

Leptomeryx is an extinct genus of artiodactyl that lived in North America during the middle Eocene through early Miocene. One of the earliest ruminants, it belongs to the extinct family Leptomerycidae, which is related to today's chevrotains. Most fossils were found in the badlands of the Midwestern United States in sedimentary rocks of the White River Group, in the Brule and Chadron formations. Additional remains have been reported from southern Canada and Mexico. The genus was scientifically described in 1853 by Joseph Leidy and includes several species.

Leptomeryx was a cat-sized animal with a short neck and long and slender limbs. The hind limbs were much longer than the forelimbs. The upper canine tooth was not enlarged, in contrast to chevrotains. The animal probably lived in herds and feed on soft plants. During the late Eocene, the genus probably lived in forests. During the early Oligocene, it adapted to the open habitats hat became prevalent at that time and became one of the most common artiodactyls.