This session highlights the central role of isotopic data in advancing interdisciplinary research on the ecological dynamics of humans and megafauna during the Quaternary period. We feature studies that use isotopic analysis to reconstruct key phenotypic traits—including mobility, dietary specialization, and behavioral adaptations to environmental change—and explore their integration with paleogenomic data to assess long-term patterns of population structure, adaptation, and extinction. We encourage submissions that combine isotope geochemistry with habitat suitability modeling and Indigenous science to provide spatiotemporal context for these ecological responses. Contributions that connect these past dynamics to present-day challenges—such as conservation planning and sustainable land-use practices, are encouraged. We welcome case studies, modeling efforts, and theoretical contributions that demonstrate innovative cross-disciplinary integration.