Mesonychidae ("Middle Claws") is an extinct family of small to large-sized omnivorous-carnivorous mammals closely related to artiodactyls (even-toed ungulates) which were endemic to North America and Eurasia during the Early Paleocene to the Early Oligocene.
The mesonychians were a group of mammals that evolved shortly after the K-T extinction. They were small and medium carnivores but eventually the became some of the largest meat-eaters of the Paleogene. They were never very numerous, but because they were related to the ancestors of whales (i.e. Ambulocetus), they are considered to be evolutionary important.
The mesonychians looked slightly like modern wolves or hyenas, but they were more closely related to hoofed animals, mostly the even-toed ungulates, like pigs and deer.
In Walking with... SeriesEdit
Andrewsarchus was one of the main characters of this episode. (It is also the only mesonychian to figure in an IP production). It was depicted as a solitary scavenger and a predator, hunting sea turtles and scavenging dead brontothere calves. It died out at the end of the Eocene.