PALEOECOLOGY OF THE ARABIAN PENINSULA DURING THE LATE MIOCENE FROM FOSSIL TOOTH ENAMEL AND PLANT WAX BIOMARKERS

The Baynunah Formation (Al Gharbia, western Abu Dhabi Emirate) contains the only known late Miocene terrestrial fossils from the Arabian Peninsula. Mammalian taxa from the Baynunah Fm. have also been reported from coeval sites in East and Central Africa and the Siwaliks of South Asia. Bio- and magnetostratigraphy suggest an age of ca. 8 to 6 Ma, a time period notable for significant ecological change marked by the spread of C₄ grasslands in Africa and South Asia. Thus, reconstructing mammalian diets and the paleoenvironment of the Arabian Peninsula can provide insight into the terrestrial ecology of this important biogeographic crossroads during a time of global ecological change. Based on renewed field work since 2002, we present paleoenvironmental and dietary reconstructions from carbon isotope data from plant wax biomarkers and carbon and oxygen isotope data from fossil tooth enamel. Carbon isotope and molecular abundance data from n‑alkanes indicate C₃-, mixed C₃-C_4, and C₄-dominated ecosystems. Similarly, carbon isotope data from fossil teeth indicate a range of C₃-, mixed C₃-C_4, and C₄ diets. In particular, equids, proboscideans, and rhinos all show distinctly variable diets that differ from their coeval African counterparts. Tooth enamel data include intratooth isotope profiles of equid teeth to evaluate seasonality. Intratooth oxygen isotope profiles indicate a highly seasonal hydroclimate regime whereas carbon profiles demonstrate large seasonal changes in the proportion of C₃ and C₄ vegetation in equid diets. The organic and isotopic data imply that the highly seasonal ecosystem supported an herbivore community with a diverse range of diets.