[citation needed] This animal shared a period and ecology with a variety of bear dogs, giant mustelid genera, and the genus of bone-crushing Canidae, Cynarctoides.

As the bear dogs and giant mustelids became extinct, Tomarctus were a hyena-like fruit-eating canidae.

Tomarctus brevirostris, synonymous with Aelurodon francisi, was named by Edward Drinker Cope in 1873.

Fossil specimens have been found as far south as Panama, east to Plum Point, Maryland, west to California, and north to Montana.

[2] Tomarctus hippophaga was first described by Matthew and Cook in 1909 from the Trojan Quarry, Olcott Formation, Nebraska.