Introduction

The major catarrhine radiation documented in the early Miocene of Africa produced a variety of intriguing primate forms, including the earliest known members of the Cercopithecoidea. In terms of taxonomic and ecological diversity, Old World monkeys (OWM) are the most successful group of anthropoid primates, and currently occupy a variety of broad ecological zones and more specific habitat types throughout Asia, Africa, and, until recently, Europe. In examining the fossil record for this group, however, it becomes apparent that although cercopithecoids are known for the last 20 million years (Myr), the modern high level of diversity is a relatively recent phenomenon.

This chapter provides a review of the distribution of east African fossil cercopithecoids in time and space. Except for two early Miocene north African sites, eastern Africa provides all of the evidence for cercopithecoid evolution in the Old World prior to about 8.5 million years ago (Ma), and for the whole of Africa prior to about 5 Ma. Consequently, most of the evolutionary events that we know about in the lineage are documented from sites in this region. Our aim is simply to summarize geological data which form a basis for hypotheses of faunal change and diversification within the superfamily. We provide a catalog of the major east African Neogene sites at which monkeys are found along with a brief account of the geological context, particularly the relative stratigraphic position and absolute dating of fossil sites when available.