Andrewsarchus

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