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Temporal range: Late Oligocene–Early Miocene
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Merycoidodontidae
Subfamily: Eporeodontinae
Genus: Eporeodon
  • Eporeodon major
  • Eporeodon occidentalis
  • Eporeodon pygmyus

Eporeodon is an extinct genus of oreodont belonging to the subfamily Eporeodontinae during the Oligocene and early Miocene epoch (33.3—20.6 mya) existing for approximately 12.7 million years.[1]

The species of the genus are among the largest members of the family Merycoidontidae. About the size of a cow, its fossils are some of the largest found in the Badlands. It was much larger than Merycoidodon and Miniochoerus, its contemporaries in the Late Oligocene. On the other hand, Eporeodon was a rare oreodont, as its fossils only make up about one percent of all oreodont fossils found in the Badlands.


Eporeodon was named by Marsh (1875). It was synonymized subjectively with Eucrotaphus by Cope (1884). It was assigned to Merycoidodontidae by Marsh (1875), Scott (1890), Thorpe (1921), Thorpe (1937), Stevens and Stevens (1996) and Lander (1998). It's synonymized with Hypselochoerus and Pseudodesmatochoerus.[2]


Eporeodon was a tremendous oreodont, growing to be about cow sized. Their skulls were much shorter and squatter than those of Merycoidodon, but were longer than those of Miniochoerus.

A single specimen was examined by M. Mendoza for body mass and estimated to have a weight of 118.3 kg (260.8 lbs).[3]


E. occidentalis (syn. E. davisi, E. leptacanthus, E. longifrons, E. perbullatus, Eucrotaphus pacificus), E. pygmyus.



  1. ^ PaleoBiology Database: Eporeodon, basic info
  2. ^ M. R. Thorpe. 1921. John Day Eporeodons, with descriptions of new genera and species. American Journal of Science
  3. ^ 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