Abstract
The vertebrate faunas which have been collected from east of Lake Rudolf include hominid remains and the earliest dated stone artefacts known. It is now possible to recognize faunal units and to establish a tentative chronology for observed faunal events. It is suggested here that the faunal sequence at East Rudolf may extend from 4.5 m.y. to about 1.3 m.y. with a significant break between about 4.0 and 2.6 m.y.