Ashley W Poust, PhD (IMAGE) PeerJ Caption Dr. Ashley Poust, a post-doctoral researcher at The Nat, has just described what is now the earliest known cat-like predator in North America, west of the Rocky Mountains. The fossil in his hand belonged to Diegoaelurus, a bobcat-sized carnivore that lived around 42 million years ago. Diegoaelurus was much smaller than the commonly known Smilodon, or sabre-tooth cat, seen in the background. Smilodon evolved roughly 40 million years after Diegoaelurus went extinct, but both animals were saber-toothed, hyper-carnivorous predators, meaning their diets consisted almost entirely of meat. Diegoaelurus and its few relatives, from Wyoming and China, were the first predators to evolve sabre-teeth, though several other unrelated animals developed this adaptation much later in time. Credit Credit: San Diego Natural History Museum. Usage Restrictions Credit: San Diego Natural History Museum. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.