Your Daily Fossil

Epicyon haydeni - the largest dog 

When: Mid to Late Miocene (~20 to 5 million years ago) 

Where: Throughout much of  North America, excepting northern Canada. 

What: Epicyon haydeni is the largest canid known. It is estimated to have weighed in at roughly 375 lbs (~170 kg).  Even though it was the size of a bear, it still retained the relatively long legs and resulting fast speed that characterizes dogs. These dogs were not just ‘scaled up’ wolves, they were much more solidly built in general and had teeth more adapted for bone crunching. While they were top predators, and perhaps hunted in packs, they were no doubt also scavengers - able to crush bone in order to eat what had been left behind by other hunters. 

Epicyon is a genus in the clade Borophaginae. This is one of the three major subclades of the dog family. The last common ancestor of the borophagines and the modern canines lived over 30 million years ago. While this subclade is characterized by large bone crushing dogs, it also contained dogs which more more resemble living forms such as the wolf. In the reconstruction image the large dog is Epicyon haydeni and the smaller is another member of the same genus.   On the whole, borophagines were more omnivorous than their canine relatives.