Mammacyon Loomis, 1936

Hunt, Robert M., 2011, Evolution Of Large Carnivores During The Mid-Cenozoic Of North America: The Temnocyonine Radiation (Mammalia, Amphicyonidae), Bulletin of the American Museum of Natural History 2011 (358), pp. 1-153 : 57

Mammacyon Loomis, 1936

TYPE SPECIES: Mammacyon obtusidens Loomis, 1936 .

INCLUDED SPECIES: Mammacyon obtusidens Loomis, 1936 ; M. ferocior , new species.

DISTRIBUTION: Early Arikareean of Oregon; early to mid-Arikareean of South Dakota; mid- or early late Arikareean of southeastern Wyoming.

DIAGNOSIS: Distinguished from Temnocyon by absence of the m1 metaconid and different M1 and P4 proportions (table 6, ratios A/B, C/D); from Temnocyon , Rudiocyon , and Delotrochanter by a more elongate m2 (ratio E/F); and from Delotrochanter by M1 proportions (ratio A/B), by P3/p3 without posterior accessory cusp, by p4 with labially (not centrally) placed posterior accessory cusp, by a sinuous (not straight) labial cingulum on m1, and by proportions of p2–4 (short broad p 2–3 in Delotrochanter , longer narrow p 2–3 in Mammacyon ). Mammacyon evolves the most extreme form of crushing P4–M1 of the subfamily. See tables 1–5.

DISCUSSION: The genus includes temnocyonines that abandon the plesiomorphic form of the cheek teeth and adopt a durophagous crushing dentition involving not only premolars but also the carnassialmolar battery. The large Mammacyon ferocior apparently evolved from the somewhat smaller M. obtusidens , both species represented by skulls and some postcrania. The genus seems restricted to the Oligocene and ranges in time from the early to midArikareean, possibly continuing into the early late Arikareean but is not known in early Miocene faunas.