Microtomarctus is an extinct genus of the Borophaginae and a small terrestrial canine which inhabited most of North America during the Whitneyan stage (20.6 Mya) of the Early Miocene subepoch through the Barstovian stage (13.6 Mya) of the Middle Miocene subepoch. Microtomarctus existed for approximately 7 million years. Like other Borophaginae it had powerful, bone crushing jaws and teeth.