Subhyracodon

Subhyracodon; Temporal range: Late Eocene to Late Oligocene, 38.0–26.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Subhyracodon occidentalis skeleton
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Family:	Rhinocerotidae
Genus:	†Subhyracodon; Brandt, 1878
Type species
	Subhyracodon occidentalis;
Species
	†S. kewi; †S. mitis; †S. occidentalis;
Synonyms
	†Anchirodon Forbes, 1881; †Anchisodon Cope, 1879; †Caenopus Cope, 1880; †Leptaceratherium Osborn, 1898;

Subhyracodon (Latin: "below the genus Hyracodon"^[5]) is an extinct genus of hornless rhinocerotids. With a length of 2.4 m (7 ft 10 in) and an estimated weight of 381 kg (840 lb) in S. mitis,^{[citation needed]} it was a tapir-sized herbivore on the plains of early Oligocene South Dakota 33 million years ago. It coexisted with other perissodactyls such as horses, brontotheres, and chalicotheres.^[6] Subhyracodon had no horns, relying more on its speed to escape from predators, but a species found at Wind Cave National Park had a pair of bony nasal ridges.^{[citation needed]} The genus Caenopus and species originally referred to as Aceratherium were synonymized into Subhyracodon.^[7] It has been suggested to be one of the oldest known members of the subfamily Elasmotheriinae by some studies,^[8] though other studies place it firmly outside the Rhinocerotinae-Elasmotheriinae split,^[9] with a 2025 study placing it as one of the most basal rhinoceroses.^[10] In terms of dentition, Subhyracodon was similar to other White River rhinoceroses, bearing no canines or third incisors. The incisor formula of Subhyracodon is 22.^[11]