Summary

1. The Hominidae and the genus Theropithecus overlap chronologically, geographically, and ecologically, and therefore provide an appropriate case study in comparative primate evolutionary biology.

2. By comparing the fossil histories of the various taxa of baboons and hominids – the African terrestrial primates (ATP) – it is possible to draw inferences about evolutionary process and pattern.

3. For baboons and hominids there is a strong relationship between generic diversity and date of origin; there is no relationship between generic duration and diversity.

4. Both baboons and hominids show a successional pattern of evolution with genera replacing each other during the Pleistocene.

5. Overall species longevity of the ATP is very similar to that of other mammalian genera. The earlier taxa of Theropithecus – are more longlasting.

6. While there is no clear trend of complete replacement of Theropithecus by Papio, the latter do become numerically dominant in the Pleistocene.

7. From a biogeographical perspective East Africa seems to be the focus for most evolutionary novelty and diversity, while other areas of Africa display some characteristics of refugia.

8. There is a close relationship between the frequency of climatic oscillations during the last five million years and species diversity, especially for Theropithecus. Other climatic variables do not show such a strong relationship.

Introduction

It has long been recognized that the evolutionary history of Theropithecus overlaps with that of the hominids. Jolly (1970) was the first to explore in detail the similarities in functional biology of the two groups, and to use Theropithecus as an analogue model for early hominid adaptation, and the underlying functional principles as a basis for interpreting hominid features.