The "Marsupial Sabertooth" possessed enormous canines that extended over the top of its head.

The Thylacosmilus atrox, an unusual animal with canine teeth similar to those of a saber-toothed cat and the wide-set eyes of a cow, lived in South America some 5 million years ago. It adapted to view the world in a unique way, with its canine teeth that jutted downward from its mouth being so large that their roots wrapped over the top of its skull. Researchers think it was a hypercarnivore, with a diet that was about 75% meat and eyes on the side of its head like a horse. Eyes don't remain in the fossil record, but eye sockets in skulls can help researchers determine more about the visual physiology of extinct creatures.