Vertebrate faunas from the Awash Group, Middle Awash Valley, Afar, Ethiopia

Abstract

ABSTRACT We present a preliminary report on vertebrate faunas from the Middle Awash Valley in the Afar Depression, from the newly described Adu-Asa, Sagantole, Matabaietu, and Wehaietu Formations. These units, together with the well-known hominid-bearing Hadar Formation and the Chorora Formation, comprise the Awash Group, which is over one kilometer thick, spans the late Neogene, and contains vertebrate fossils throughout. Significantly, periods are represented—the late Miocene to early Pliocene and Middle to late Pleistocene—that are poorly or incompletely known elsewhere in East Africa. At least 24 mammalian families and 170 species are represented in the Awash Group. In the newly described stratigraphic units, faunal change is documented for a number of mammalian groups. This is especially true for Proboscidea, specifically anancine gom-photheres (Gomphotheriidae: Anancinae) and elephants (Elephantidae: Stegotetra-belodontinae and Elephantinae), the Artiodactyla, particularly suids (Suidae), bovids (Bovidae) and hippopotamids (Hippopotamidae), and Primates (Cercopithecidae: Cercopithecinae and Colobinae). Available radiometric dates and biostratigraphy indicate that the time span represented by the Adu-Asa and Wehaietu Formations is at least 5.0–6.0 m.y. long, making the Middle Awash sequence one of the most extensive faunal records in the African Neogene.