STABLE ISOTOPE RECORD OF CLIMATE AND ECOLOGIC CHANGE IN THE TURKANA BASIN

The Turkana Basin in northern Kenya provides a superb record over the last 7 million years of mammalian evolution along with a history of ecologic and climatic change. Carbon isotopes document major dietary changes during this interval in several mammal families, including elephantids, giraffids, and suids. We also find long term trends in stable oxygen isotopes in a variety of materials: lacustrine carbonates, soil carbonates, and the enamel of hippopotamids, equids, rhinocerotids, bovids, suids, and elephantids. Each of these sources records an increase in d¹⁸O of about 0.5 permil per million years. Such long term trends indicate important climate changes taking place in East Africa perhaps related to changes in the Inter-Tropical Convergence Zone ((ITCZ).