Mesonyx

Mesonyx is an extinct genus of mesonychid, a group of hoofed mammals that lived during the Eocene epoch. Mesonyx was a relatively small mesonychid, with most specimens measuring around 1.5 meters (5 feet) in length. It possessed a wolf-like body with a long tail and a narrow skull. Its teeth were adapted for shearing flesh, indicating a carnivorous or omnivorous diet. The toes of Mesonyx ended in small, hoof-like nails, a characteristic feature of mesonychids that reflects their evolutionary relationship to ungulates (hoofed mammals).

Fossils of Mesonyx have been found in North America, primarily in the Bridger Formation of Wyoming. These deposits date back to the Eocene, approximately 55 to 34 million years ago. Mesonyx likely inhabited riparian environments, preying on fish, small mammals, and possibly scavenging carrion. Its skeletal structure suggests it was a moderately agile animal. The discovery of Mesonyx has contributed significantly to understanding the early diversification of mammals and the evolutionary lineage that eventually led to modern ungulates, although the exact placement of mesonychids within this lineage has been a subject of debate among paleontologists. Recent studies have placed them as an early offshoot of the ungulate evolutionary tree, rather than direct ancestors to cetaceans as was once hypothesized.