Dissacus sp.

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 : 40

Dissacus sp.

REFERRED SPECIMEN: RAM 6507, talonid of m1 (possibly m2) from RAM locality V94014 , member 4a (fig. 12D).

DESCRIPTION AND DISCUSSION: Mesonychids are among the rarest mammals in North American Paleogene faunas ( O’Leary and Rose, 1995) and the only specimen recovered from the Goler Formation (RAM 6507) is a well-preserved talonid of a lower molar of Dissacus , probably an m1 (fig. 12D), which is 5.50 mm in width. Based on size, RAM 6507 cannot be referred to a specific species with confidence as Dissacus navajovius , D. argenteus , D. willwoodensis , and D. serior are about the same size, and D. praenuntius is only about 15% larger than the other four ( O’Leary and Rose, 1995). The only morphological feature present in RAM 6507 that may be taxonomically significant is the nearly symmetrical shape of the talonid caused by equal sloping of its labial and lingual surfaces (as seen in distal view). This condition is similar to m1s of D. navajovius ( O’Leary and Rose, 1995: fig. 3 ).

Figures

FIGURE 3. Occlusal views of mandibles of Nannodectes lynasi, new species. A. RAM 9044, holotype of Nannodectes lynasi, right dentary fragment with damaged i1, alveolus of p2, p3–m3 from RAM locality V200510. B. RAM 9429, right dentary fragment with i1 root and p3–m3 from RAM locality V200706. C. RAM 10029, right dentary fragment with damaged p4–m3 from RAM locality V200804.