Oreodont

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Sometimes called a prehistoric "ruminating hog," the oreodont was a sheep-sized, cud-chewing plant-eater with a short face, tusk-like canine teeth, heavy body, long tail, short feet, and four-toed hooves.

The now-extinct suborder Oreodonta was distantly related to pigs, hogs, camels, hippopotamuses, and the pig-like peccaries. Indeed, some scholars place the oreodont family Oreodontidae (also known as Merycoidodontidae) within the pig-related suborder Suina (a.k.a. Suiformes). Still other experts put the oreodonts together with the short-lived cainotheres in the taxonomic suborder Ancodonta comprising these two groups of extinct ancodonts.

Scholars agree, however, that the oreodont was an early form of even-toed ungulate, belonging to the order Artiodactyla among the placental mammals. Over 50 species of Oreodonta have been described in the paleozoological literature. Of these, by far the most well-known oreodont genus is Merycoidodon, formerly and popularly known as Oreodon.

However, some other oreodont genera common in the fossil record are Brachycrus, Eporeodon, Leptauchenia, Merychyus, Mesoreodon, Promerycochoerus, and Protoreodon. And still other genera are Desmatochoerus, Diplobunops, Eucrotaphus, Hadrohyus, Paradesmatochoerus, Phenacocoelus, Pseudodesmatochoerus, Sespia, and Ustatochoerus. In informal discussion, all these genera are sometimes referred to (incorrectly) as Oreodon.

This stocky prehistoric mammal grazed amid the grasslands, prairies or savannas of North and Central America throughout much of the Cenozoic era. First appearing 48 million years ago (m.y.a.) during the warm Eocene epoch of the Paleogene period, the oreodonts dominated the American landscape 34 to 23 m.y.a. during the dry Oligocene epoch of the late Paleogene. But they mysteriously disappeared 4 m.y.a. during the colder Pliocene epoch of the late Neogene period, long before the arrival of humans in the New World.

Today, fossil jaws and teeth of the Oreodonta are commonly found amid the Oreodon beds of the White River badlands in South Dakota, Nebraska, and Wyoming. Many oreodont bones have also been reported at the John Day Fossil Beds National Monument in Oregon.