Correlation between the oxygen isotope ratio of North American bison teeth and local waters: Implication for paleoclimatic reconstructions

The oxygen isotope ratios of tooth enamel carbonate from 64 North American bison (Bison bison) from eleven locations were measured. The mean enamel oxygen isotope ratios for bison populations ranged from 28.3 to 15.9 ‰ SMOW and correlated well with the annual mean oxygen isotope ratios of local surface waters and precipitation. The standard deviation of oxygen isotope values among different individuals within each bison population averaged 1.0 ‰, and ranged from 0.7 to 1.4 ‰. The variability of enamel oxygen isotope ratios was not significantly different among different populations and did not correlate with changes in temperature, precipitation, or relative humidity. These results demonstrate that the average oxygen isotope values of bison tooth enamel can be used for use as a quantitative proxy for reconstructing the values of surface waters, and therefore may provide valuable paleoclimatic information. This study provides a baseline comparison for analyses of the oxygen isotope ratios of bison and other large herbivores from across North America.