Dogs The Size of Grizzly Bears Roamed Prehistoric Earth

You may think Great Danes or St. Bernards are pretty massive, but ancient dogs have our current canines beat. The largest dog to ever live was about the size of a grizzly bear—and hunted in the same way as a modern-day fox, say scientists.

Called the Epicyon haydeni, this prehistoric dog lived about 16 million years ago. According to an article published in Scientific Reports, it was a relative of the first-ever species of dog, Hesperocyon gregarious. Both prehistoric pooches pounced on their prey the way coyotes and foxes do, CT scans revealed.

Scientists at the universities of Edinburgh and Vienna scanned fossils and modern skeletons from a group of mammals known as carnivorans, which includes foxes, wolves, cougars, and leopards, as well as extinct species.

The research was conducted in an effort to better understand the inner ears of 36 types of these mammals, as inner ear structure helps determine which ancient carnivorans are closer in relation to dogs (Canoidea) or cats (Feloidea). The inner ear structure also revealed the hunting styles of each animal, as this structure adapts overtime to accommodate balance and stability in different hunting situations.

The takeaway: The next time a big dog leans on you with his full weight, just remember to be grateful he’s not from prehistoric times!