Zinc Isotope Systematics in Terrestrial Food Webs: Implications for the Trophic Ecology of Tropical Hunter-Gatherer of Late Pleistocene Southeast Asia

This thesis explores the use of “non-traditional” stable isotopes in archeology and paleontology, specifically isotopes of the trace element zinc (Zn) from tooth enamel to obtain dietary information from fossil specimens. Throughout this thesis, the use of zinc stable isotopes is explored through methodological and application perspectives, addressing some analytical challenges and developing study designs that are optimized for extracting robust dietary data from fossil materials. In particular, this method allows assessing the trophic level of a consumer, i.e., its relative dietary reliance on plant or animal resources. While nitrogen stable isotope (δ15N) analysis of bone or dentin collagen is an established method for trophic level assessment, such method is limited by protein preservation. Trophic level assessment of fossils beyond the Late Pleistocene, or coming from adverse taphonomic settings such as tropical and subtropical environments, are mostly unfeasible with this conventional method. However, the 66Zn/64Zn ratio (expressed as δ66Zn value) in bioapatite shows promise as a proxy to infer trophic and dietary information from fossil vertebrates, even under adverse taphonomic conditions. Indeed, zinc is incorporated as a trace element in the enamel bioapatite and thus has a better long-term preservation potential of diet-related isotope compositions than collagen-bound nitrogen. The first part of this thesis aims at giving an overview of zinc isotope analysis in paleodietary reconstructions, outlining principles of zinc isotope systematics and highlighting the potential and challenges of this analysis for archeology and paleontology. The lack of a strongly defined interpretative framework and comparative data are key obstacles to using zinc stable isotopes for paleodietary reconstructions. The second part of this thesis examines the preservation potential of pristine diet-related zinc isotope ratios under tropical conditions with poor collagen preservation, such as the studied depositional context in ...