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Understanding the ecological factors that contributed to the late-Pleistocene large mammal extinction event (~10,000 years ago) has been particularly challenging due to the lack of a modern comparative framework. However, existing research suggests that changes in landscapes and the distribution of vegetation likely contributed to the downfall of megaherbivores. In this study, we create a dietary model for late-Pleistocene herbivores using enamel carbon (δ13C) and oxygen (δ18O) isotope values from extant white-tailed deer (Odocoileus virginianus). More specifically, we investigate the isotopic signature of enamel during the formation of M1, M2 and M3 as a means of considering annual variation in diet as well as variation across the life of the individual. The δ13C value of enamel apatite reflects the δ13C value of ingested foodstuffs, offset by a diet-tissue fractionation factor. Based upon this scheme, herbivorous mammals can be divided into three different dietary categories: C3 browsers (3/C4 mixed-feeders (>-8‰ to 4 grazers (>-1‰). Variability in δ18O values within a single tooth are indicative of seasonal changes in precipitation or temperature given the relationship between enamel δ18O values and ingested water. Higher δ18O values are suggestive of elevated evaporation or decreased precipitation, frequently induced by warm/dry conditions. With this information, we will be able to better understand existing isotopic data collected from mammoth (Mammuthus columbi) and long-horned bison (Bison latifrons) in southeastern North America. Finally, these data (particularly oxygen isotopes) will be valuable for considering modern and ancient changes in rainfall across southeastern North America.


File nameDate UploadedVisibilityFile size
19 Jul 2022
56.7 MB



  • Subject
    • Biology

  • Institution
    • Dahlonega

  • Event date
    • 17 April 2020

  • Date submitted

    19 July 2022

  • Additional information
    • Acknowledgements:

      David Patterson, Jessica Patterson