Mio-Plio-Pleistocene geology and palaeobiology of Etosha Pan, Namibia
Résumé
Etosha Pan, northern Namibia, at nearly 5,000 km', is one of the largest in the world. A major hurdle to understanding the geological history of Etosha Pan has been the lack of dated horizons in the local stratigraphic record. We here report the discovery of fossil plants, invertebrates and vertebrates at several distinct horizons within the pan and its immediate vicinity, which reveal the presence of deposits ranging in age from Late Miocene to Late Pleistocene. Most of the floor of the pan consists of Late Miocene deposits whereas in islands and ridges within the pan and along its margins there occurs a discontinuous deposit of Pliocene, Pleistocene sediments up to 20 metres thick. Finally, there are discontinuous patches of green silts on Pelican Island at an altitude of ca 1093 metres, some 8-10 metres above the floor of the pan, which attest to a Late Pleistocene lacustrine episode. Similar aged deposits at the western end of Oshigambo Peninsula has yielded a rich and diverse mammalian fauna containing remains of the aquaphile bovid Tragelaphus spekei (the sitatunga). The discovery of Mio-Pliocene fossils in Elosha is important as it helps to fill whal used to be a large geographic gap in the African palaeonlological map of this epoch. Laie Miocene sites in particular, are poorly represented over much of the continent, being concentrated in the rift valleys of East Africa, the Chad basin, the Maghreb and north African littoral zone.