Nothocyon ("spurious dog"[1]) is an extinct genus of carnivoran in the family Subparictidae which inhabited North America during the late Oligocene.

The species Canis geismarianus was originally described by Edward Drinker Cope in 1878, based on a jaw fragment with a single m1 that came from the John Day Formation in Oregon.

[8] However, in 1992, a thorough re-description of the holotype was published by Wang & Tedford, who matched it with associated upper and lower teeth from the same locality, and re-assigned the 1881 and 1883 canid material to the species Cormocyon copei, and placing Nothocyon geismarianus as a stem arctoid.

[9] A further study in 1999 reassigned Nothocyon lemur and N. roii to Cynarctoides, N. latidens and N. annectens to Phlaocyon, N. regulus as a synonym of Desmocyon thomsoni.

[10] Another two species assigned at one time to Nothocyon, "N." gregorii and "N." vulpinus, and the variant N. geismarianus var mollis, have been reassigned to the genus Leptocyon.