Metamynodon is an extinct genus of amynodont perissodactyls whose known species lived in North America (White River Fauna) during the early Oligocene, although the questionable inclusion of M. mckinneyi could extend their range back in time, to the Middle Eocene.They were large, displaying a suit of semiaquatic adaptations similar to those of the modern hippopotamus despite their closer affinities with rhinoceroses.