OLIGORYCTIDAE Asher, McKenna, Emry, Tabrum, and Kron, 2002

Murphey, Paul C. & Kelly, Thomas S., 2017, Mammals from the earliest Uintan (middle Eocene) Turtle Bluff Member, Bridger Formation, southwestern Wyoming, USA, Part 2: Apatotheria, Lipotyphla, Carnivoramorpha, Condylartha, Dinocerata, Perissodactyla and Artiodactyla, Palaeontologia Electronica (Cambridge, England: 2003) 20 (2), pp. 1-51 : 23-25

Family OLIGORYCTIDAE Asher, McKenna, Emry, Tabrum, and Kron, 2002

unnamed apternodontid sp.

Figure 10.1-4 , Table 2

Referred specimens. From SDSNH Locality 5841: partial LM1 or 2, SDSNH 110348; partial Rm1 or 2, SDSNH 110349. From UCM Locality 92189: partial dentary with Rm1-2, UCM 68965.

Description. The partial M1 or 2 is broken, missing the parastylar lobe of the stylar shelf and the labial portion of the anterior cingulum. Even in its broken state, certain characters can still be distinguished. It is zalambdodont with a sharp, tall, large paracone and lacking a metacone. The protocone is robust with a sharp apex, but is significantly lower in height than the paracone. The anterior cingulum is moderately strong and extends labially from the protocone to the point where the tooth is broken off. The ectoflexus is deep with a distinct concave labial border. A paraconule and metaconule are lacking.

The partial dentary with m1-2 was not available at the time of our study (G.F. Gunnell, personal communication, 2015). The partial m1 or 2 is missing most of the tip of the paraconid, but the following characters can still be distinguished. The trigonid is very tall and compressed anteroposteriorly with the metaconid only slightly lower in height than the protoconid. The talonid is extremely reduced, only represented by an incipient entoconid and narrow shelf (unbasined) that does not extend to the labial corner of the tooth. The anterior cingulid is moderately strong, extending lingually from the anterolabial base of the protoconid and terminating near the anterior base of the paraconid.

Remarks. Asher et al. (2002) provided a brief description and illustration of a very small, unnamed apternodontid from the middle Eocene of the western Interior (see also McKenna et al., 1962; Emry, 1990), including specimens from the Bridger Formation at Tabernacle Butte and the TBM. Based on their cladistic analysis, Asher et al. (2002) found the new unnamed apternodontid was most closely related to Oligoryctes Hough, 1956 . The TBM specimens agree well in size and occlusal morphology with this unnamed taxon.

Figures

FIGURE 10. Oligoryctidae and unnamed lipotyphlan from TBM. 1-4, unnamed apternodontid sp.: partial LM1 or 2 (SDSNH 110348) in occlusal (1) and anterior (2) views; partial Rm1 or 2 (SDSNH 110349) in occlusal (3) and labial (4) views. 5-6, unnamed lipotyphlan sp., partial dentary with Rp4 (DMNH 75258) in occlusal (5) and labial (6) views. Scale bars equals 1 mm.