Abstract:

The Hualongdong site in Dongzhi County, Anhui Province, represents the most comprehensive Paleolithic site in China since Zhoukoudian, yielding abundant hominin fossils alongside stone tools and other evidence of human activities. Notably, it has also produced a substantial assemblage of mammalian fossils. As a key species in China's Quaternary mammalian fauna, the Pleistocene gaur [Bos (Bibos) sp.] shares close phylogenetic relationships with its extant counterparts. However, systematic understanding of this fossil Bos (Bibos) sp. species remains limited due to fragmentary fossil materials and methodological constraints. The dental fossils of Bos (Bibos) sp. from Hualongdong site provide crucial materials for investigating its dietary habits, ecological niche, paleoenvironment and ecosystem. This study employs multidisciplinary approaches including CT three-dimensional modeling, phytolith analysis, and stable isotope analysis to systematically investigate Bos (Bibos) sp. dental fossils. CT modeling precisely identified dental calculus locations, enabling subsequent phytolith extraction and morphological characterization from calculus deposits. Concurrently, carbon stable isotope analysis was conducted on tooth enamel. Results reveal that the late Middle Pleistocene Hualongdong site Bos (Bibos) sp. feed on herbaceous plants of varying heights. Carbon isotope data indicate a primary reliance on C₃ plants from the site and surrounding areas, supplemented by limited C₄ plant consumption (δ¹³C values: -10.3‰ to -4.6‰). Phytolith analysis specifically indicates frequent ingestion of Poaceae and Zingiberales species. These findings collectively indicate that Bos (Bibos) sp. primarily foraged in warm environments dominated by C₃ vegetation during the late Middle Pleistocene. The diverse phytolith assemblages and isotopic signatures reflect rich regional vegetation heterogeneity, providing ample food resources. Furthermore, the common occurrence of Pleistocene Bos (Bibos) sp. fossils in alluvial plains, mountain valleys, and karst caves suggests their preference for open forest areas with grassy patches. This ecological pattern aligns with their mixed dietary strategy of feeding on both C₃ and C₄ plants. This research establishes novel phytolith and isotopic records for understanding Bos (Bibos) sp. paleodietary ecology while contributing to Middle-Late Pleistocene paleoclimatic and paleoecological reconstructions in Anhui Province. The integrated methodology demonstrates the efficacy of combining Plant microfossils and geochemical proxies in paleodietary studies, offering insights into herbivore-environment interactions during the Pleistocene.

Key words: Pleistocene, Hualongdong site, Bibos sp., phytoliths, diet