Sciuravus nitidus Marsh, 1871

Kelly, Thomas S. & Murphey, Paul C., 2016, Mammals from the earliest Uintan (middle Eocene) Turtle Bluff Member, Bridger Formation, southwestern Wyoming, USA, Part 1: Primates and Rodentia, Palaeontologia Electronica 7 (8), pp. 1-55 : 21

Sciuravus nitidus Marsh, 1871

Figure 7.1 , Table 4

Referred specimen. From UCM Locality 92189: partial P4, UCM 68430.

Description. The partial P4 is moderately well worn with the enamel abraded away along the lingual aspect of the metacone. It has a transversely elongate oval occlusal outline. The anterior cingulum is strong, slightly lower in height than the metaloph, and extends labially from the protocone to join the anterolabial corner of the paracone. The protocone is moderately large and connected to the paracone by a complete protoloph. The metacone is nearly as large as the paracone. A hypocone is lacking. The metaloph extends lingually from the metacone to join an indistinct metaconule (slight swelling) and terminates just short of the posterior cingulum. The posterior cingulum is robust and extends from the protocone to the posterolabial corner of the metacone.

Remarks. Based on its occlusal outline and lack of a distinct hypocone, UCM 68430 can be confidently identified as a P4. In size and occlusal morphology, UCM 68430 is indistinguishable from the P4s of S. nitidus ( Troxell, 1923b; Wilson, 1938b, Dawson, 1961) and is referred to the species.

Figures

FIGURE 7. Larger Sciuravidae from TBM. 1, Sciuravus nitidus, RP4, UCM 68430. 2-4, Taxymys lucaris: 2, RM1 or 2, UCM 68307; 3, LM1 or 2, UCM 95762; 4, LM3, DMNH 75336. 5-7, Tillomys senex: 5, Lm1 or 2, DMNH 75328; 6, Rm1 or 2, DMNH 75279; 7, Rm1 or 2, SDSNH 110363. 8-9, Tillomys? parvidens: 8, Rm1 or 2, SDSNH 110379; 9, Lm3, DMNH 75288. All occlusal views. Scale bar equals 1 mm.