Pronghorn (Antilocapra americana) enamel phosphate δ18O values reflect climate seasonality: implications for paleoclimate reconstruction

Stable oxygen isotope compositions from vertebrate tooth enamel are commonly used as biogeochemical proxies for paleoclimate reconstructions. However, the utility of enamel isotopic values across species varies due to differences in rates of enamel deposition and mineralization as well as sources of ingested water, body water residence times, and species’ physiology. We evaluate the use of stable oxygen isotope compositions from pronghorn (Antilocapra americana Gray, 1866) enamel for the amplitude reconstruction of terrestrial paleoclimate seasonality. We serially sampled the third lower molars of pronghorn from Wyoming for oxygen isotope composition in phosphate (δ18OPO4) and compared patterns to: (1) interpolated and (2) measured yearly variation in central Wyoming environmental waters (δ18Ow) as well as to (3) δ18O values from sagebrush leaves and stems in the same region. Although we recognize the numerous factors influencing the composition of mammal body water, our null hypothesis...