They soon faced formidable foes like the saber-toothed cat as well as bear dogs. The last of the entelodont went extinct between 19 and 16 million years ago. Since then, these fearsome ancient ...

In "Prehistoric World: Over 1,200 Incredible ... recent discoveries that many people may not have heard of before. "Bear-dogs are some of my personal favorite carnivores," Woodruff said.