Amphicyon ingens was the largest of the bear dogs.
Bear dogs (Amphicyonids) were caniform carnivorans that were either closely related to modern bears or derived from basal caniforms. They first evolved in Eurasia, where they started out as smaller animals that actually resembled hybrids between dogs and bears.
The largest members of the bear dog family were in the genus Amphicyon, and Amphicyon ingens was the largest of that genus and of the entire family. It lived in North America from 13 to 20 million years ago, and like most of its genus, it was a sort of combination between a very large bear and a big cat.
It weighed as much as 1,300 pounds, and it likely preyed on the various ancient North American megafauna in much the same way lions or tigers prey on things like gaur and giraffe. Keep in mind that this animal was more than twice the size of a typical adult male tiger, so it would have been preying on really large megafauna. With the exception of the modern era, North America has usually had mammalian megafauna, and these “big cat bears” would have been well-positioned to prey on these large beasts.
