HYAENODON

extinct genus of early, primitive mammalian carnivores that first appears in the fossil record in late Eocene time and persists through the Oligocene (the Oligocene Epoch, which followed the Eocene, began 36.6 million years ago and lasted 12.9 million years). Hyaenodon, a creodont (see Creodonta), was a large and efficient predator. Its skull was long and narrow, with teeth that were well adapted to a predaceous mode of life; they were large and able to bite or crush.