Summary

1. The Ternifine Theropithecus, referred to T. oswaldi leakeyi, is here described for the first time.

2. Published analyses of the site and its fauna suggest that it may date to about 700 Ka, that the paleoenvironment was quite open and arid around the central spring-fed lake, and that the bone accumulation was partly of human cultural origin.

3. Three well-preserved specimens of the male mandible document all of the morphology of this element, revealing minor differences from described Olduvai jaws.

4. The dental sample includes 68 teeth (not counting definite antimeres), of which five are deciduous.

5. The degree of sexual dimorphism in lower canine length and width is strong, as known for other populations of this subspecies; this is one additional line of evidence supporting the interpretation of male gender for the holotype of ‘Simopithecus Jonathan’ from the Olduvai Masek Beds – its P3 mesial flange was small because it received a small C1.

6. In both cheek tooth width (length is a poor comparator because it decreases greatly with advanced wear) and canine length and width, the Olorgesailie sample has the highest mean among all T. o. leakeyi populations, and its variation range encompasses all of them.

7. Molar size does not increase monotonically with time, but varies somewhat, with a possible decrease in the youngest fossils (e.g. Masek and Thomas Quarries).

Introduction

The largest sample of Theropithecus from North Africa is that collected from Ternifine (once Palikao, now Tighenif), Algeria, by Gamille Arambourg and Hoffstetter in 1955–6.