Temnocyon Cope, 1878

TYPE SPECIES: Temnocyon altigenis Cope, 1878 .

INCLUDED SPECIES: Temnocyon altigenis Cope, 1878; T. subferox, new species; T. ferox

Eyerman, 1896; T. percussor Cook, 1909; T. fingeruti, new species; T. macrogenys, new species .

DISTRIBUTION: Early Arikareean, Oregon and California; late Arikareean, Oregon and western Nebraska; latest Arikareean, southeastern Wyoming.

DIAGNOSIS: A paraphyletic genus distinguished from other temnocyonines by presence of a metaconid on m1; by plesiomorphic form and proportions of M1–2, m2 (with labially situated proto-and hypoconids), upper and lower carnassials, and premolars (P4–M1 ratios A/B, C/D, table 6). See tables 1–5.

DISCUSSION: The genus includes stem temnocyonines that preserve the plesiomorphic form of the cheek teeth, only slightly modified in the younger and larger derivative species of the genus. T. subferox apparently evolved from T. altigenis, the earliest and smallest temnocyonine species. Larger and more dentally derived T. ferox, T. percussor, and T. fingeruti retain a number of primitive dental features and represent larger species evolved from within the T. altigenis – T. subferox group. The enormous T. macrogenys, the last representative of the genus, is most likely derived from T. percussor . The genus ranges in time from the earliest to latest Arikareean.