Andrewsarchus

Andrewsarchus mongoliensis (Andrews + Greek ἀρχός, "ruler"), was a predatory artiodactyl, closely related to entelodonts, hippos,whales and Mesonychids

Andrewsarchus Temporal range: Eocene
The only skull of Andrewsarchus, on display at the American Museum of Natural History in New York City.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Genus:	†Andrewsarchus Pao, 1923
Species
A. mongoliensis Pao, 1923 (type)

Andrewsarchus lived during the Eocene, about 45 to 36 million years ago. Because Andrewsarchus is only known from a skull and a few other bones, the animal's full appearance is unknown, but based on what is known of it and its relatives, it was most likely a stocky hoofed entelodont-like animal. It had a long snout with large, sharp teeth and flat cheek teeth that may have been used to crush bones. Because Andrewsarchus is only known from a skull and a few other bones, whether it was an active predator or merely a large scavenger is open to debate, as is its exact time range.

Hypothetical reconstruction, with basis from better-known relatives.