Eucyon (Greek for "original dog"); pronounced YOU-sigh-on
Plains of North America
Late Miocene (10-5 million years ago)
Size and Weight:
About 3 feet long and 25 pounds
Medium size; enlarged sinuses in snout
To simplify matters just a bit, the late Miocene Eucyon was the last link in the chain of prehistoric dog evolution before the appearance of Canis, the single genus that encompasses all modern dogs and wolves. The three-foot-long Eucyon was itself descended from an earlier, smaller genus of dog ancestor, Leptocyon, and it was distinguished by the size of its frontal sinuses, an adaptation linked to its diverse diet. It's believed that the first species of Canis evolved from a species of Eucyon in late Miocene North America, about 5 or 6 million years ago, though Eucyon itself persisted for another few million years.