Pharsophorus tenax Ameghino
P. tenax Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 504.
Fig. 140. Left upper jaw—½ natural size;
A, molars 3 and 4 from above;
B, molars from external side.
The species was based on a fourth premolar which was 10 mm. long as compared with 13 mm. in P. lacerans. We found on the Chico del Chubut, west of Puerto Visser, both an upper and lower jaw belonging to this species, which give us the knowledge of the upper dentition for the genus. The species is distinguished by the smaller size, relatively heavy jaws, and plump teeth, indicating a heavier built animal than P. lacerans. The following measurements distinguish the species.
Fig. 141. Right mandible—½ natural size.
| Specimen 3192 | |||||
|---|---|---|---|---|---|
| Upper dentition, | length premolar 1 to molar 3 | 76 mm. | |||
| Upper dentition, | premolar 3, | length | 10.5 mm., | width | 6 mm. |
| Upper dentition, | molar 1, | length | 11.5 mm., | width | 8.5 mm. |
| Upper dentition, | molar 2, | length | 12 mm., | width | 9 mm. |
| Upper dentition, | molar 3, | length | .55 mm., | width | 12 mm. |
| Specimen 3004 | ||||
|---|---|---|---|---|
| Lower dentition | ||||
| Distance from premolar 1 to molar 3 | 76 mm. | |||
| Molar 1, | length | 11 mm., | width | 6 mm. |
| Molar 2, | length | 13 mm., | width | 6 mm. |
| Molar 3, | length | 13 mm., | width | 7 mm. |
| Distance from premolar 1 to molar 3 | 30 mm. | |||