The late Middle Pleistocene Zhongshan cave fauna from the Bubing Basin, southern China

The karstic caves in the Bubing Basin, Guangxi, southern China, contain abundant Quaternary mammalian fossils. These cave sites are located at varying altitudes that have been roughly correlated with chronological age (higher caves are older, lower caves are younger). A growing number of recent studies have established a regional biochronological sequence for these Bubing caves from the Early to the Late Pleistocene. Here, we describe a new mammalian assemblage from the Zhongshan Cave, that dates to the late Middle Pleistocene - Marine Isotope Stage 6 (191–130 ka). The age is supported by minimum ages derived from U-series dating of the deposits, and the ESR/U-series dating of one Rhinoceros tooth (∼184 ka). The Zhongshan mammalian assemblage, comprising 33 taxa of large-sized mammals, belongs to the Middle Pleistocene “Ailuropoda-Stegodon” faunal unit and, in this respect, most closely resembles the Ganxian fauna (362–168.9 ka). The high diversity and abundance of ruminant Artiodactyla (versus Perissodactyla) in the Zhongshan fauna suggest a diversity of forest to more open habitats in the Bubing Basin during this period.

The Zhongshan fauna fills a gap in the biochronological framework of southern China, offering new insights into the evolutionary history of some mammalian lineages in the Bubing Basin. Overall, data indicate major changes in the Early to Late Pleistocene faunal sequence, particularly with more turnover during the Early-Middle Pleistocene transition compared to the Middle-Late Pleistocene transition.

Comparison between faunas from the Bubing Basin with those from sites in the Chongzuo area, also in Guangxi, southern China, highlights two major phases in the general decline of large-sized mammals during the Middle to Late Pleistocene transitional period. In that respect, our results provide an updated biochronological background for further analyses of the region.