PALEODIETARY RECONSTRUCTION OF MIOCENE FAUNAS FROM PASALAR, TURKEY USING STABLE CARBON AND OXYGEN ISOTOPES OF FOSSIL TOOTH ENAMEL

Miocene-age (similar to 15 Ma) deposits at Pasalar in northwest Tur kev contain abundant and well-preserved dental remains from a variety of herbivores. We used the carbon and oxygen isotopic compositions of inorganic carbonate in enamel from these teeth to reconstruct the paleodiet and sources of body water, respectively, of Miocene mammals. The delta(13)C (PDB) values of carbonate in the enamel fall between -13.5 and -9.0 parts per thousand, indicating a diet dominated by C-3 plants for all mammals. Some species are distinctly different isotopically from others, likely reflecting on variation in the delta(13)C values of the plants being consumed. Giraffokeryx and Caprotragoides display the most depleted delta(13)C values, probably indicating they were feeding upon C-3 plants experiencing low water stress and/or CO2 recycling, such as in a forest. Hypsodontus and Conohyus, on the other hand, consistently display the most enriched delta(13)C values. They were therefore consuming isotopically enriched C-3 plants or a small quantity of C-4 grasses. In either case, a more open habitat is indicated, The other species we measured, including Griphopithecus, yielded intermediate values. The delta(18)C (PDB) values of the carbonate in fossil enamel also differ substantially between some taxa, and probably show that mammals such as Giraffokeryx, like East African giraffes today, were drawing their water from sources enriched in O-18, such as from the top of a forest canopy.