Fossil Canids of the National Park Service

We've been taking a tour of Mammalia for the past two annual "Fossil [Group] of the National Park Service", and this year we'll make it three in a row with man's best friends, the Canidae. The dog record starts up in the Eocene with the hesperocyonines, who held court through the Oligocene but then petered out in the Miocene. Turning up in the Oligocene are the borophagines, or "bone-crushing dogs," and the canines, which include wolves, foxes, domestic dogs, and close relatives. Borophagines, as the nickname suggests, had robust jaws and teeth, which doesn't mean they should be typecast as slavering hypercarnivorous brutes (canids in general have been pretty flexible about diet over their history). They drop out of the record at about the end of the Pliocene, leaving the field clear for the canines, which had been a fairly minor component of the canid radiation until about the Late Miocene. If you're interested in paleontological nitty-gritty on these two groups, check out Wang et al. (1999) on borophagines and Tedford et al. (2009) on canines. Canids, incidentally, are a North American invention, and unlike some other groups that originated in North America (camels, horses, rhinos), they have never gone extinct on the continent.