Prodiacodon crustulum Novacek, 1977

Clemens, William A., 2015, Prodiacodon crustulum (Leptictidae, Mammalia) from the Tullock Member of the Fort Union Formation, Garfield and McCone Counties, Montana, USA, PaleoBios 32 (1), pp. 1-17 : 3

Prodiacodon crustulum Novacek, 1977

Figs. 2–8

Holotype — UCMP 114990, UCMP loc. V74122, left upper molar (M1 or M2).

Revised diagnosis— Postcanines are smaller than those of Prodiacodon puercensis . Differing from P. puercensis , upper molars of P. crustulum have relatively wider stylar shelves, variable presence of a small stylocone, smaller hypocones, shorter and smaller (in basal dimensions) metacones relative to paracones. Also, the paraconule and smaller metaconule are well developed and situated on the pre- and postprotocrista closer to the apex of the protocone than to the bases of the paracone and metacone. Differing from the type and paratype of P. puercensis , on only a few upper molars a small cuspule is present anterolabial to the paraconule. In both species, on P5 and the upper molars the precingulum is crenulated by series of folds and/or cuspules as is the transversely longer postcingulum. Unlike P. puercensis , in which it is salient, the mesial end of the crown of p5 is blunt with a small cusp present lingual to the paraconid. Talonids of m1 and m2 differ from those of the paratype of P.puercensis in usually having only three cusps; the majority lacks an entoconulid. An entoconulid is present on the talonids of most m3s.

Hypodigm— Other than a fragment of a dentary with p2, a fragment of p4 and p5, UCMP 224048, the hypodigm consists of isolated teeth ( Table 1). Identification of the positions of the isolated teeth in the dentition has been based primarily on comparisons with the paratype of P. puercensis ( Novacek 1977, fig. 8; 1986, fig. 4; Matthew 1918, figs. 6-9; 1937, plate 55, figs. 1-8) and more recent leptictids. Dimensions of the postcanines are given in Table 2.

Description

Dentary, p2, p4, and p5 — A right dentary (UCMP 224048, Fig. 2) preserves p2, a fragment of p4, and p5. The p2 has a single central cusp (protoconid). A crest extends mesially from the protoconid to a miniscule cusp

p 5: V73080, 186622, 224048; V73082, 192149; V74119, 224052; V74122, *114978; V 74123, *114993.

?dp 5: V73080, 224050; V73082, 192148, 218894; V74120, 224051; V75193, 218895.

m 1-2: V72125, 192072; V72128, 192073-192075; V72129, 192076-192080; V72134, 224055; V73080, 186604, 186643, 189420, 192081-192090, 224053; V73082, 192091, 192093; V73096, 110534, 224054; V74119, 192095; V74122, *114981, *114986, 192096-192099; V74123, *114991, *114992, V74127, 192103; V75193, 192101, 192102, 218896; V99438, 192094, 192104, 192095, 192107-192110, 218897, 218898, 224056, 224057.

m 3: V72131, 224058; V74112, *114985; V75193, 224061; V75194, 224062; V78082, 189518; V73080, 224059, 224060; V99438, 218899, 224063.