>>16703033 (OP) The largest member of the dog family (Canidae) to ever roam the Earth was the prehistoric predator Epicyon haydeni. Also known as the "bone-crushing dog," this colossal canid lived in North America between 16 and 5 million years ago. It rivaled a modern brown bear in size, measuring up to 8 feet long and weighing well over 300 pounds.