INVESTIGATING THE ECOLOGY OF EXTINCT PROBOSCIDEANS FROM THE CINCINNATI REGION USING STABLE ISOTOPES
Based on tooth morphology and previous isotopic work, we expected that mammoths and mastodons would have differing δ13C values, indicating C4 grazing and C3 browsing niches, respectively. We compared 87Sr/86Sr ratios in waters and proboscideans tooth enamel to identify local residents and potential migrants. We then used δ18O values to pinpoint possible origins for migrant individuals. As anticipated, mammoths have significantly higher δ13C values than mastodons. This suggests that mammoths may have consumed more C4 grasses, although one mammoth has δ13C values suggesting a C3-based diet. Overall, strontium isotope ratios for proboscideans and local waters are indistinguishable. However, one Mammut molar has significantly higher 87Sr/86Sr ratios, suggesting this animal immigrated into the area from somewhere outside of the Midwest. Combined 87Sr/86Sr and δ18O values suggest this animal may have migrated from the southern Appalachians. These results will supply a foundation for future work on proboscideans and other extinct megafauna from the Midwestern United States.