Hyaenodon Skull (Hyaenodon cruentus)Hyaenodon is an extinct genus of carnivorous mammals that first appeared in the fossil record about 42 million years ago during the middle of the Eocene Epoch and persisted until about 25 million years ago near the end of the Oligocene Epoch. Hyaenodon cruentus was a, medium to large sized creodont (extinct carnivorous mammal) that lived during the Oligocene to early Miocene in North America, appearing similar to a large, robust dog. A dominant