Hyracodon ('hyrax tooth') is an extinct genus of perissodactyl mammal.

Temporal range: Middle Eocene–Late Oligocene
Hyracodon nebraskensis.jpg
Skeleton in Natural History Museum of Los Angeles
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Hyracodontidae
Subfamily: Hyracodontinae
Steinmann & Doderlein, 1890
Genus: Hyracodon
Leidy, 1856[1]
  • H. browni
  • H. leidyanus
  • H. medius
  • H. nebraskensis
  • H. petersoni
  • H. affinis
  • H. eximus
  • H. modestus
  • H. primus
  • H. princeps
  • H. priscidens
Restoration by Charles R. Knight.

It was a lightly built, pony-like mammal of about 1.5 m (5 ft) long. Hyracodon's skull was large in comparison to the rest of the body. Hyracodon's dentition resembled that of later rhinoceroses, but it was a much smaller animal and differed very little in appearance from the primitive horses of which it was a contemporary (32–26 million years ago). It had a short, broad snout and its long, slender limbs had three digits.[2]

Restoration by Heinrich Harder.

Like the primitive horses, hyracodonts inhabited open forests and wooded steppes and turned from browsing foliage to grazing grass. They died out without leaving any descendants and they mark the end of the phylogenetic branch of hornless, running rhinoceroses.

This small, fast-running creature was a close relative of the largest land mammal that ever lived, the 20-ton Paraceratherium.


  1. ^ McKenna, M. C; Bell, S. K. (1997). Classification of Mammals above the Species Level. Columbia University Press. ISBN 0-231-11012-X.
  2. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 283–284. ISBN 1-84028-152-9.


  • Benes, Josef (1979). Prehistoric Animals and Plants. Prague, CZ: Artua. p. 220.