Guess what its closest modern relative is. Go on. Guess.
It's a goddamn twelve foot long Eocene death-sheep.
(Text from Wikipedia- http://en.wikipedia.org/wiki/Andrewsarchus_mongoliensis)
Andrewsarchus was a primitive, heavily-built, wolf-like, hoofed mammal that lived during the Eocene Epoch, roughly between 45 and 40 million years ago. It walked on four short legs and had a long body, a long tail, and feet with hoofed toes. It had a long snout with large, sharp teeth and flat cheek teeth that may have been used to crush bones; however, since Andrewsarchus is only known from a skull and a few bones found, whether it was an active predator or merely a large scavenger is open to debate, as is its exact time range.
It is assumed that it had hoofed toes similar to those of Mesonyx or Sinonyx, and is regarded as a relative of artiodactyl ungulates.
(Read- relative of giraffes, deer, antelopes, cattle, and- yup- sheep.)
Best animal evar? I quite think so.