Delotrochanter, new genus

TYPE SPECIES: Delotrochanter oryktes, new species .

INCLUDED SPECIES: Delotrochanter petersoni, new species; D. oryktes, new species; D. major, new species .

DISTRIBUTION: Mid- and late Arikareean of northwest Nebraska; latest Arikareean of Nebraska-Wyoming boundary in vicinity of the Niobrara River .

ETYMOLOGY: From the Greek, delos, for ‘‘evident,’’ and trochanter, ‘‘runner,’’ to emphasize the cursorial nature of these carnivores.

DIAGNOSIS: Distinguished from Temnocyon by absence of the m1 metaconid; by a centrally placed m2 protoconid and hypoconid; and by proportions of P4 and M1 (table 6, ratios A/B, C/D); from Mammacyon by a short, less elongate skull, by shorter broad p2–3 and less elongate m2 (ratio E/F); and from Rudiocyon by a more elongate m2 (ratio E/F). See tables 1–5.

DISCUSSION: The genus includes temnocyonines that abandon the plesiomorphic form of the cheek teeth and adopt a crushing durophagous dentition different from that of Mammacyon in proportions of the carnassial-molar battery. Delotrochanter petersoni appears to be a mid-sized ancestral species evolving to the large D. oryktes and the even larger D. major . The genus ranges in time from the midto latest Arikareean but is not certainly known in the early Arikareean interval.