Tomarctus ("cutting bear") is an extinct canid of the subfamily Borophaginae which inhabited most of North America during the late Early Miocene subepoch to the Early Barstovian age of the Middle Miocene subepoch (23—16 mya). Tomarctus existed for approximately . Tomarctus is derived from the Nothocyon and gave rise to Borophaginae, a short-face, heavy-jawed canine usually massive in size. This animal shared a period of time and ecology with a variety of other bear dogs like the giant mus… (More on Tomarctus)