Kanyimangin: a new 1 million years old sit in West-Turkana, Kenya

The Early to Middle Pleistocene Transition (EMPT 1250-750 ka) is a period characterised by major environmental changes. These changes are reflected in the archaeological and faunal records which are marked by behavioural, cognitive (Acheulean specialisation/expansion) and morphological (encephalisation) innovations within the genus Homo. Unfortunately, the EMPT African hominin fossil record is scarce and poorly correlated with the archaeological record. Here we present faunal and chronometric data of a newly discovered EMPT site in West Turkana: Kanyimangin.In August 2017, the Trans-Evol Project started fieldwork in the floodplain of the Kerio River (Turkana Basin, Kenya), identifying a new palaeontological and archaeological locality. Kanyimangin is located within the Kalabata river (a tributary of the Kerio river) circular anomaly, where ca. 15-meter-deep sediments are preserved from erosion by a series of five sandstones. Although there has been almost no focussed local palaeontological and geochronological study, sediments in that area were believed to be older than 3.7 Ma. However, using combined palaeomagnetism and bio-chronological approaches, we obtain an age estimate between 0.90 and 1.19 Ma. Kanyimangin has yielded substantial lithic (n=344) and faunal (n=2155) assemblages originating partly from buried contexts. The latter comprises 212 individual specimens (NISP) distributed across 20 taxa. The faunal spectrum is composed of both aquatic and terrestrial taxa, including: Palaeoloxodon (Elephas) recki cf. recki, Panthera sp., Hyaena hyaena, Equus grevyi, Rhinocerotidae, Kolpochoerus (limnetes) heseloni, Phacocoerus sp., Hippopotamus amphibius, Syncerus caffer, Aepyceros melampus, Alcephalus buselaphus, cf. Nanger granti and a Renducini as well as the narrow-snouted Euthecodon brumpti, a broad-snouted crocodile, turtles/tortoises, snakes, fish and amphibians. Palaeomagnetic results reveal a normal polarity for the archaeology-bearing sandstone and evidence for a subsequent period of reverse polarity. Together with the presence of Palaeoloxodon recki cf. recki recovered from the same sandstone, this suggests a Matuyama age for the site after the Olduvai subchron. To date, most faunal remains were recovered from survey, which limits their biostratigraphic potential; however, the presence of well-fossilised Phacochoerus sp. and Alcephalus buselaphus specimens recovered on the surface of the archaeology-bearing sandstone equally suggests a Jaramillo (1.06–0.90 Ma) or Cobb Mountain (1.19 Ma) age for the site