Protictis paralus Holtzman, 1978

Lofgren, Donald, Mckenna, Malcolm, Honey, James, Nydam, Randall, Wheaton, Christine, Yokote, Bryan, Henn, Lexington, Hanlon, Whitney, Manning, Stephen & Mcgee, Carter, 2014, New records of eutherian mammals from the Goler Formation (Tiffanian, Paleocene) of California and their biostratigraphic and paleobiogeographic implications, American Museum Novitates 2014 (3797), pp. 1-60 : 6-8

Protictis paralus Holtzman, 1978

HOLOTYPE: SMM P77.6.64, right dentary with canine and p4–m2 from the Judson Locality, Tongue River Formation, North Dakota.

REFERRED SPECIMEN: RAM 6927, right dentary fragment with c, p1–2, p4, and partial m1 from RAM locality V200001, member 4a ( fig. 2C–D ).

DESCRIPTION: The canine of RAM 6927 is large. Its apex extends anteriorly and its root curves posteriorly underneath p1. A wide diastema separates the canine and p1, which has a tall and narrow anterior cusp, and a small and low posterior accessory cusp ( fig. 2C–D ). The diastema separating p1 and p2 is short, and p1 and p2 are similar in morphology, with p2 a larger version of p1, but with a relatively tall anterior cusp. Two alveoli filled with sediment mark the position of the missing p3, which indicates the p2–p3 diastema was short and the p3–p4 diastema was absent. A mental foramen is positioned below the anterior root of p3.

A well-developed anterior cuspule and large main cusp and two small posterior cuspules are present on p4. The apex of the anterior cuspule is conical and separated from the main cusp by a broad carnassiform notch. The first posterior cuspule is positioned on the posterior slope of the main cusp, with a small carnassiform notch separating them. A third carnassiform notch separates the first posterior cuspule from the slightly lower second posterior cuspule. A small talonid basin is developed between the posterior cuspules that opens lingually and cusps and cuspules of p4 are aligned in a slight arc that opens lingually in occlusal view.

The m1 of RAM 6927 has a tall and well-preserved trigonid and a low and damaged talonid. The protoconid is the tallest cusp, with a distinctly smaller metaconid that is taller and slightly larger than the paraconid. Part of the talonid is missing and only a small hypoconid is present whose position is significantly lingual to the protoconid, suggesting that the talonid was small. Depth of the mandible below p2 is 1.09 mm, and 2.01 mm below m1.

DISCUSSION: The presence of a sectorial main cusp, a smaller but well-developed anterior cuspule, small posterior cuspules developed on the posterior flank of the main cusp, and a small talonid basin, are features of the p4 of RAM 6927 that indicate it represents Protictis . Torrejonian and Tiffanian species of Protictis from the Bighorn and Clark’s Fork basins, including P. schaffi , P. agastor , P. dellensis , P. haydenianus , P. laytoni , and P. paralus , were noted by Gingerich and Winkler (1985) as usually differentiated by size. Later, Polly (1997) removed P. schaffi , P. dellensis , P. laytoni from Protictis by synonymizing P. schaffi with Viverravus politus , Protictis dellensis with Didymictus proteus, and Protictis laytoni with Viverravus bowni . More recently, two Torrejonian species of Protictis , P. simpsoni and P.minor from the San Juan Basin of New Mexico, were described by Meehan and Wilson (2002). Protictis agastor , P. minor , P. simpsoni , and P. haydenianus are larger than P. paralus ( Gingerich and Winkler, 1985: tables 4–5, 8; Meehan and Wilson, 2002: table 2; Holtzman, 1978: table 31). Direct comparison of the holotype of P. paralus (SMM P77.6.64) and RAM 6927 indicates that the p4 of RAM 6927 is nearly identical in all respects to the p4 of the holotype, except the anterior accessory cusp of RAM 6927 is slightly larger. The p4 of both the holotype and RAM 6927 have a small talonid basin and are similar in size ( table 2).

The m1 of RAM 6927 has a metaconid that is slightly taller and larger than the paraconid. In the m1 of the holotype, the paraconid is slightly larger than the metaconid, but a second m1 (SMM P77.8.190) of P. paralus from the type locality has a paraconid and metaconid equal in size and height, indicating that some variation can be expected in m1 trigonid cusp morphology in P. paralus . These three m1s (RAM 6927, SMM P77.6.64, SMM P77.8.190) have identical trigonid widths ( table 2). Based on nearly identical p4s, little difference in m1 trigonid cusp development, and close similarity in size between RAM 6927 and the holotype of P. paralus, RAM 6927 is confidently referred to this rarely reported small species of Protictis .

Figures

FIGURE 2. Mandibles and teeth of Protictis, Bessoecetor, and Taeniodonta. A. Occlusal view of RAM 9099, right dentary fragment with m2–3 of Bessoecetor septentrionalis from RAM locality V200510; B. labial view of RAM 9099. C. Lingual view of RAM 6927, a right dentary fragment with c, p1–p2, p4, and partial m1 of Protictis paralus from RAM locality V200001 (with partial imprint of dentary); D. occlusal view of p1–2, p4–m1 of RAM 6927. E. Lingual view of partial m1 of RAM 7246, left dentary fragment with partial m1 of Protictis cf. P. agastor from RAM locality V200001; F. labial view of partial m1 of RAM 7246; G. occlusal view of RAM 7246. H. Posterior view of RAM 15328, partial lower canine of a taeniodont from RAM locality V200612; I. anterior view of RAM 15328. Scale bar for C–D also applies to E–G.