Andrewsarchus. Illustration and photo-reconstruction Andrewsarchus mongoliensis (bone cruncher), the largest carnivorous land mammal that lived during the Eocene epoch between 32 to 60 million years ago. 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 single enormous skull (83 cm long and 56 cm wide), whether it was an active predator or a large scavenger is open to debate, as is its exact time range. Though scientists can't be sure, the huge skull suggests the animal may have been twice as big as a grizzly bear, making it the largest carnivorous land mammal of all time. It is believed that Andrewsarchus fed on turtles, because the only Andrewsarchus fossil was found in a prehistoric coastal area. Some scientists think Andrewsarchus is a close relative of whales, since they share a similar jaw structure.