Homacodon sp.

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 : 36

Homacodon sp. , cf. H. vagans Marsh, 1872a

Figure 14 , Table 4

Referred specimen. From UCM 92189: partial Rp3, UCM 95810.

Description. The partial p3 has the anterior portion of the crown broken off near the anterior half of the protoconid. It has a tall, central protoconid and a central posterior ridge with minor irregularities (bumps) that descends posteriorly from the protoconid apex to join a centrally positioned, distinct cuspid (hypoconulid?) at the posterior edge of the talonid. A second posterior ridge is present that is lower in height than the central posterior ridge. This second ridge rapidly descends posteriorly from the posterolingual edge of the protoconid then continues along the lingual border and then turns labial to join the central talonid cuspid. A third low, short ridge is present that extends labially from the central talonid cuspid to the labial edge of the tooth. A metaconid is lacking.

Remarks. Stucky (1998) briefly proposed that more than one species of Homacodon may be present in the Bridger Formation. However, besides relative size differences, he did not elaborate much on what other characters can be used to distinguish them, and his proposal has not yet been supported by a subsequent publication. The holotype of Homacodon vagans came from the Twin Buttes Member (Br3, Bridger D) at Henry's Fork ( West, 1984; Stucky, 1998). Although broken, UCM 95810 agrees well in size and occlusal morphology with the p3 of H. vagans , including two posteriorly descending ridges from the protoconid (one centrally and one lingually positioned) that join a centrally positioned talonid cuspid and the absence of a metaconid. The p3 of H. vagans has a small, but distinct paraconid present. Whether UCM 95810 possessed a paraconid cannot be determined because the anterior portion of the tooth is broken off. UCM 95810 probably represents H. vagans , but because its incomplete state does not allow further comparison, we refer it to Homacodon sp. , cf. H. vagans .

Figures

FIGURE 14. Homacodon sp., cf. H. vagans from TBM. Partial Rp3 (UCM 95810) in occlusal (1), lingual (2), and labial (3) views. Scale bar equals 1 mm.