Stable isotope records of inland California megafauna -- New insights into Pleistocene paleoecology and paleoenvironmental conditions

Paleodietary studies of California megafauna have focused primarily on the coastal late Pleistocene Rancho La Brea tar seeps (RLB) in Los Angeles, while other sites remain understudied. This study examined two Pleistocene fossil localities from inland California (San Joaquin Valley) and report ?13C and ?18O values measured from tooth enamel of mammalian megafauna at both sites. The late Pleistocene McKittrick tar seeps in Kern County have a similar fauna to RLB. The middle Irvingtonian (~700,000 year old) Fairmead Landfill site, near Chowchilla, contains a megafaunal assemblage dominated by Equus, Camelops and Mammuthus.\nThis study uses stable isotope values measured in carnivore and herbivore tooth enamel to investigate paleodietary and paleoecological patterns at both sites. The ?13C values of tooth enamel are controlled by diet and can be used to investigate resource usage and partitioning among and between taxa. In large mammals ?18O ratios are controlled by drinking water, and by proxy, climate. Ontogenetic serial tooth ?18O and ?13C reveal seasonal trends in resource usage, from which we can infer patterns of forage availability.\nStable carbon values from 16 taxa, reveal significant differences both between taxa and between localities. Faunal ?13C differ significantly (p<0.001) between Fairmead and McKittrick, ranging from -13.5??? to -8.2??? and -11.8 to -0.7???, respectively. No significant differences were detected in ?18O between sites (p=0.7).