An age for Kajong, a Miocene fossil site east of Lake Turkana, Kenya

Abstract The Kajong Formation in Marsabit District, northern Kenya has yielded a Miocene mammalian fauna consisting of nine taxa. It is capped by a basalt 40 Ar/ 39 Ar dated at 19.1 ± 0.1 Ma, and a volcanic clast from a conglomerate within the formation yielded an age of 20.3 Ma, only slightly older. The entire fauna from this site thus lies close to the base of the Miocene Epoch and is older than 19.2 Ma. The site has yielded some of the oldest examples of Archaeobelodon filholi , Prodeinotherium hobleyi , and Gomphotherium sp. in east Africa.