Scenopagus curtidens ( Matthew, 1909 )

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 : 6-10

Scenopagus curtidens ( Matthew, 1909)

Figure 3.1-8 , Table 2

Referred specimens. From SDSNH Locality 5841: Ldp4, SDSNH 110344. From UCM Locality 92189: LM1, UCM 68966; partial Rm1 or 2, UCM 70677; Rm1 or 2, UCM 95684; Lm1 or 2, UCM 95685; Rm3, UCM 68968.

Taxon/Specimen number Position ap tr tra trp Scenopagus priscus

UCM 95683 m 1 or 2

SDSNH 110345 m 3

Scenopagus curtidens

UCM 68966 M1

SDSNH 110344 dp4

UCM 70677 p. m1 or 2

UCM 95684 m 1 or 2

UCM 95685 m 1 or 2

UCM 68968 m 3

Sespedectinae , genus undet.

SDSNH 110343 p. m1 or 2

Entomolestes westgatei n. sp.

UCM 68540 p4

UCM 95686 p4

m1

UCM 95687 (holotype) p4

m1

UCM 67884 p. m1

m2

m3

UCM 78746 p. m1

UCM 68423 m 2

UCM 68973 m 2

Centetodon bemicophagus

UCM 68681 P4

SDSNH 110347 M3

SDSNH 110391 p4

UCM 68899 m 1 or 2

UCM 71128 m 1 or 2

DMNH 75256 m 1 or 2

DMNH 75257 m 3

Centetodon pulcher

UCM 67889 p4

UCM 68534 p4

UCM 95767 p4

m1

1.40 - 1.02b 1.05

1.35 - 0.85 0.67

1.77 2.49 - -

1.60 - 0.91 1.00

1.88 - 1.32 -

1.80 - 1.49 1.51

1.74 - 1.46 1.49

1.60 - 1.12 0.94

1.36b - 1.44 -

0.90 - 0.67 0.62

0.95 - 0.71 0.58

1.56 - 0.93 0.95

0.90 - 0.72 0.62

1.59 - 0.94 0.95

- - 0.90 0.88

1.41 - 0.93 0.93

1.08 - 0.64 0.57

- - 0.93 -

1.39 - 0.91 0.93

1.36 - 0.95 0.87

1.46 1.49 - -

0.93 1.90 - -

1.21 - 0.67 0.67

1.49 - 1.00 0.85

1.34 - 0.77 0.70

1.50 - 0.85 0.70

1.46 - 0.85 0.70

1.55 - 0.92 0.87

1.59 - 0.93 0.87

1.79 - 0.93 0.93

2.01 - 1.28 1.18

TABLE 2 (continued).

Description. To the best of our knowledge, the dp4 of Scenopagus curtidens has not been previously described. It exhibits an anteriorly inclined trigonid that is about twice as tall as the height of the talonid, a relatively tall paracristid, a centrally positioned hypoconulid and is lacking a distinct paraconid, characters that are typical of Scenopagus . It is further characterized by the following: 1) molariform; 2) a rounded protoconid and metaconid, about equal in height; 3) a robust, deeply basined talonid with a distinct entoconid, hypoconid, and hypoconulid, all nearly equal in height; 4) a moderately tall cristid obliqua, extending from the anterior edge of the hypoconid to terminate at the posterior wall of the trigonid, just lingual of the protoconid apex; 5) a deep lingual talonid notch; and 6) a shallow ectoflexid.

The lower molars are very similar morphologically to those referred above to Scenopagus priscus , but differ by being significantly larger in size and by having a slightly stronger anterior cingulid and a slightly straighter paracristid and postprotocristid. Otherwise, the above description of the lower molars of S. priscus also applies to those referred above to S. curtidens .

Based on a well-preserved partial maxilla with P3-M3 from the Aycross Formation of the Absaroka Range, Wyoming, Bown (1982) described in detail the upper cheek teeth of S. curtidens . The referred M1 (UCM 68966) from the TBM is nearly identical in size and occlusal morphology to that of S. curtidens from the Aycross Formation. The TBM M1 differs from that of the Aycross specimen only by having a slightly larger hypocone and slightly less developed anterior cingulum, differences that can be attributed to individual variation.

Remarks. The five molars from the TBM are indistinguishable in size and occlusal morphology to those of Scenopagus curtidens (Bown, 1982) and are referred to the species. One isolated tooth, which is identified as a dp4, is tentatively referred to the species because it is compatible in size and general occlusal morphology to the cheek teeth of S. curtidens .

Figures

FIGURE 3. Sespedectidae from TBM. 1-8, Scenopagus curtidens: LM1 (UCM 68966) in occlusal view (1); Ldp4 (UCM 110344) in occlusal (2) and labial (3) views; Lm1 or 2 (UCM 95685) in occlusal (4) and labial (5) views; Rm1 or 2 (UCM 95684) in occlusal (6) and labial (7) views; partial Rm3 (UCM 68968) in occlusal view (8). 9-11, Scenopagus priscus: Rm1 or 2 (UCM 95683) in occlusal (9) and labial (10) views; Rm3 (SDSNH 110345) in occlusal view (11). 12- 13, Sespedectidae, genus undetermined, partial Lm1 or 2 (SDSNH 110343) in labial (12) and occlusal (13) views. Scale bar equals 1 mm.

FIGURE 4. Entomolestes westgatei new species from TBM. 1-2, partial dentary with Lp4-m1 (UCM 95687, holotype) in labial (1) and occlusal (2) views. 3-5, partial dentary with partial Rm1 and m2-3 (UCM 67884) in occlusal (3), labial (4), and lingual (5) views. Scale bar equals 1 mm.

FIGURE 5. Entomolestes westgatei new species from TBM. Specimens showing position of mental foramen (MF) and alveoli for antemolars anterior of p4. See text for proposed alveolar homologies. 1-2, partial dentary with Lp4-m1 (UCM 95686, m1 not shown) in occlusal (1) and labial (2) views. 3-4, partial dentary with Lp4-m1 (UCM 95687, holotype, m1 not shown) in occlusal (3) and labial (4) views. Scale bar equals 1 mm.

FIGURE 6. Geolabididae from TBM. 1-4, Centetodon bembicophagus: LP4 (UCM 68681) in occlusal view (1); partial Lm1 or 2 (UCM 68899) in occlusal view (2); Lm1 or 2 (DMNH 75256) in occlusal view (3); Lm3 (DMNH 75257) in occlusal view (4). 5-10, Centetodon pulcher: partial dentary with Lp4-m1 (UCM 95767) in occlusal (5) and labial (6) views; Rm1 or 2 (UCM 95768) in occlusal view (7); partial dentary with Lp1 and p4-m3 (UCM 68963) in occlusal (8), labial (9), and lingual (10) views. Scale bar equals 1 mm.

FIGURE 7. Nyctitherium gunnelli new species from TBM, associated Lp4-m2 (SDSNH 110393, holotype): Lp4 in occlusal (1), labial (4), and lingual (7) views; Lm1 in occlusal (2), labial (5), and lingual (8) views; Lm2 in occlusal (3), labial (6), and lingual (9) views. Scale bar equals 1 mm.

FIGURE 8. Nyctitheriidae from TBM. 1-6, Nyctitherium velox: RM2 (DMNH 75292) in occlusal view (1); RM2 (UCM 95771) in occlusal view (2); RM2 (UCM 68581) in occlusal view (3); RM3 (DMNH 75291) in occlusal view (4); partial Lm2 (DMNH 75317) in occlusal view (5); partial Lm2 (SDSNH 110409) in occlusal view (6). (7), Pontifactor bestiola, RM1 (UCM 71129) in occlusal view. 8-10, Nyctitherium gunnelli new species, LP4 (UCM 95769) in occlusal (8), labial (9), and lingual (10) views. Scale bar equals 1 mm.