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Temporal range: 35–5 Ma
Late Eocene to Miocene[1]
Merychyus elegans, Harrison, Nebraska, USA, Middle Miocene - Royal Ontario Museum - DSC00103.JPG
M. elegans fossil, Royal Ontario Museum
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Suborder: Tylopoda
Family: Merycoidodontidae
Genus: Merychyus

Merychyus is an extinct genus of terrestrial herbivore of the family Merycoidodontidae (oreodont), endemic to North America during the Oligocene-Pliocene subepochs (24.8—4.9 mya) existing for approximately 19.9 million years.[2]

Merychyus was a cud-chewing plant-eater with a short face, tusk-like canine teeth, heavy body, long tail, short feet, and four-toed hooves.


Restoration of a herd of Merychyus

Merychyus was named and assigned to Merycoidodontidae by Joseph Leidy (1858) and Lander (1998); and to Merychyinae by Parris and Grandstaff (2003).[3]


Four specimens were examined by M. Mendoza for body mass and estimated to have a weight of:

  • Specimen 1: 98.4 kg (216.9 lbs).
  • Specimen 2: 81.5 kg (179.6 lbs).
  • Specimen 3: 83.1 kg (183.2 lbs).
  • Specimen 4: 112.3 kg (247..5 lbs).[4]

Fossil distribution[edit]

Fossils are widespread through the central and western United States.


M. arenarum (syn. M. delicatus, M. euryops), M. crabilli, M. elegans (syn. M. jahnsi) (type species), M. major (syn. Merycochoerus californicus), M. medius, M. minimus (syn. M. calaminthus, M. paniensis, M. verrucomalus), M. novomexicanus (syn. Ustatochoerus skinneri), M. relictus, M. smithi (syn. M. calimontanus, Ticholeptus tooheyi), Ustatochoerus leptoscelos


  1. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 270. ISBN 1-84028-152-9. 
  2. ^ PaleoBiology Database: Merychyus, basic info
  3. ^ B. Lander. 1998. Oreodontoidea. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary mammals of North America 402-425
  4. ^ M. Mendoza, C. M. Janis, and P. Palmqvist. 2006. Estimating the body mass of extinct ungulates: a study on the use of multiple regression. Journal of Zoology