An ecological snapshot of the early Pleistocene at Kokiselei, Kenya

Fauna from hominin-bearing Pliocene and Pleistocene sites in the Omo-Turkana Basin have long been valuable in assessing how the climate of East Africa over the past 5 Ma has changed. Stable C and O isotope ratios in the enamel of fossil herbivores at a Paranthropus boisei-bearing Pleistocene archaeological site on the west side of Lake Turkana give insight on vegetation coverage and moisture conditions for this area between 1.87 and 1.80 Ma; samples were from a faunal assemblage associated with excavations at two sites at Kokiselei. Average δ13C enamel values of -1.6 ± 3.6 / (n=80) indicate a C4-dominated landscape. Equids, suids, hippopotamids, and most bovids have C4-dominated diets; tragelaphines have mixed C3- C4 diets; Giraffa and Deinotherium have a C3-dominated diet. Average δ 18O values of +0.2 ± 1.7‰ indicate the presence of water relatively less enriched in 18O than modern Turkana Basin waters that have been measured. Low δ18O values in evaporation-sensitive taxa such as Giraffa indicate less aridity than modern Turkana grassland and shrubland. Overall results suggest that during the early Pleistocene, P. boisei inhabited dominantly open wooded grassland that experienced a significantly different moisture regime from that of the present day.