Merycochoerus (Greek: "ruminant" (merux)-like "swine" (khoiros)) is an extinct genus of oreodont of the family Merycoidodontidae, endemic to North America. They lived during the Early Oligocene 33.9âÂÂ30.8 mya, existing for approximately . Fossils are widespread through the western United States.
Merycochoerus was a cud-chewing plant-eater with a long face, tusk-like canine teeth, heavy body, long tail, short feet, and four-toed hooves. The long animals are thought to have been amphibious, as members of the genus possessed an elongated, barrel-shaped body and short limbs that are typical adaptations found in semi-aquatic mammals.