Trogolemur storeri, Perry & Dutchak & Theodor, 2023

Perry, Jonathan M. G., Dutchak, Alex R. & Theodor, Jessica M., 2023, New primates from the Eocene of Saskatchewan: Revision of the primates from the Cypress Hills Formation with description of new taxa, Palaeontologia Electronica (a 20) 26 (2), pp. 1-19 : 7-8

Trogolemur storeri n. sp.

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Type. Left upper first molar discovered by K. A. Prufrock in matrix collected by John Storer and crew, RSM P3450.1466 (fig. 2A, 2E) .

Horizon and type locality. Interbedded conglomerate and coarse sandstone of Uintan middle Eocene age, Swift Current Creek locality, southwestern Saskatchewan, Canada ( Russell, 1965a, 1965b, 1972; Storer, 1978, 1996).

Diagnosis. Approximately 30% smaller in linear dimensions than Trogolemur leonardi ; buccal notch much shallower; greater development of lingual cingulum. Differs from Trogolemur myodes in M1 being wider relative to length, more pronounced lingual cingulum, much shallower buccal notch. Differs from Trogolemur amplior in being considerably smaller. Differs from Trogolemur myodes in m3 having much more taper distally, with long and narrow hypoconulid lobe. Differs from Trogolemur fragilis in having a less distinct paraconid on m3 that sits closer to the metaconid, slightly longer and narrower hypoconulid lobe.

Etymology. ‘storeri’ named for John E. Storer who described the first primates from the Swift Current Creek locality and in honor of his extensive contributions to Canadian paleontology.

Hypodigm. Lm3, RSM P3450.1467; Rm3, RSM P3450.1468.

Summary of Changes

The following list summarizes suggested changes to the record for the genus Trogolemur . • Trogolemur myodes USNM 417396 is an M1, not an M2. • Trogolemur leonardi RSM P 1899.1014 and RSM P1899.1016 are M3s, not M2s. • Trogolemur leonardi RSM P 1899.1007 is an M2, not an M1. • Trogolemur leonardi RSM P 1899.1002, RSM P1899.1003, and RSM P1899.1004, all identified as m1 or m2, are likely m1s.

New records of Trogolemur include a left M1 (RSM P3450.1466), a left m3 (RSM P3450.1467), and a right m3 (RSM P3450.1468). These are described as a new species, Trogolemur storeri . With very little morphological difference between Trogolemur storeri and Trogolemur leonardi apart from size, and with little geographic separation, it seems likely that the former is a phyletic antecedent to the latter.

New Discoveries – Walshina

An upper molar resembling Trogolemur leonardi , but approximately 50% larger in linear dimensions, was discovered in the SCC matrix ( Figure 5 ). Slight erosion along the buccal and distal margins has altered the outline of the tooth. Nevertheless, this tooth (RSM P3450.1469) is recognizable as a primate right M1 (or possibly M2). The tooth has a broad basin distal to the protocone; this is distinctive of trogolemurin omomyoids. It greatly resembles CM 15635 (LM1) from the Uintan Badwater Creek, Wyoming. That tooth was originally described as Phenacolemur mcgrewi by Peter Robinson, then allocated to Ignacius by Bown and Rose ( Robinson, 1968; Bown and Rose, 1976). Subsequent analysis by López-Torres and colleagues has shifted this material from the Paromomyidae (Plesiadapiformes) to the Trogolemurini ( Omomyidae ), renaming the relevant material as Walshina mcgrewi (López-Torres, et al., 2018). We provisionally refer the new tooth to Walshina mcgrewi .

Given the rarity of primate material at SCC, it is interesting that there are two known species of trogolemurin omomyid at this locality. Thus, diversity of trogolemurins is slightly higher here than in contemporaneous faunas in Wyoming or southern California. Despite the enormous geographic separation, trogolemurins existed simultaneously in all these places. This speaks to the similarity in climate across much of North America in the middle Eocene, and/or to the adaptability of these tiny primates.

Figures

FIGURE 4. New lower third molars of Trogolemur from Swift Current Creek. A: Lm3, RSM P3450.1467. B: Rm3, RSM P3450.1468. Compare with m3s of Trogolemur myodes AMNH 12599 (Matthew, 1909, fig. 5), USNM 417355 (Emry, 1990, fig. 6D-F), and USNM 417356 (Emry, 1990, fig. 6A-C). Scale bar is 1 mm long.