Merycoidodontoidea, previously known as "oreodonts" or "ruminating hogs,"[citation needed] are an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth.

As their name implies, some of the better known forms were generally hog-like, and the group has traditionally been placed within the Suina (pigs, peccaries and their ancestors), though some recent work suggests they may have been more closely related to camels.

put the oreodonts together with the short-lived cainotheres in the taxonomic suborder Ancodonta comprising these two groups of extinct ancodonts.

All scholars agree, however, that the oreodont was an early form of even-toed ungulate, belonging to the order Artiodactyla.

The last researchers to fully review oreodont taxonomy, C. Bertrand Schultz and Charles H. Falkenbach,[5] have been criticized for erecting excessive numbers of genera, based in part on apparent anatomical differences between different specimens that were actually taphonomic deformations due to postburial forces.

[3][6][7] This diverse group of stocky prehistoric mammals grazed amid the grasslands, prairies, or savannas of North and Central America throughout much of the Cenozoic era.

[citation needed] Oreodonts underwent a huge diversification during the Oligocene and Miocene, adapting to a number of ecological niches, including: The family Merycoidodontidae is divided into eleven subfamilies, with four genera not included in any subfamily (incertae sedis) because they are either regarded as basal oreodonts, or their status within the family remains uncertain.