A GLIMPSE AT THE ECTOTHERMS OF THE EARLIEST FAUNA FROM THE EAST AFRICAN RIFT (LOKONE, LATE OLIGOCENE OF KENYA)

We describe here an ichthyological and herpetological assemblage that was obtained from washing-screening sediments from the early late Oligocene locality of Lokone, Kenya. This provides original information on the hitherto oldest known fauna from the East African Rift since it started to open from north to south during the Oligocene. The description of the fossil remains allows the identification of crocodiles (crocodylids), squamates (lacertid and Serpentes), turtles (pelomedusoids cf. Erymnochelys group), dipnoan (?Protopterus sp.), and actinopterygian fishes (Polypterus sp., Heterotis sp., Gymnarchus sp., Hydrocynus sp., Sindacharax sp. and other alestids, a claroteid, a cichlid, possibly a Distichodus, and other indeterminate fish). The preservation of this material testifies to a certain level of hydrodynamism, and the ecology of these ectotherm vertebrates suggests that freshwater environment was developed in this area. Moreover, the assemblage corresponds to herpeto- and ichthyofaunas that prefigured the modern African diversity as early as the Oligocene, before the Miocene invasion by Asian fish. It thus testifies to connections between the newly formed hydrographical system in the Turkana Basin with the Lokone main hydrographical system beginning at a very early stage of the Eastern Rift development.