Fossil flying squirrels (Petauristinae, Sciuridae, Rodentia) from the Yumidong Cave in Wushan County, Chongqing, China

Flying squirrels are important forest environment indicators. There have been many reports on them from fossil localities of the Late Cenozoic in southwest China, but relatively few detailed studies have been carried out on them. Numerous flying squirrel fossils of the Mid-Late Pleistocene were unearthed from the Yumidong Cave in Wushan County, Chongqing Municipality, China, providing excellent materials for morphological comparison and further research on this group. Four species have been recognised from this locality, including Pteromys volans, Trogopterus xanthipes, Belomys pearsonii and Aeretes melanopterus. P. volans and A. melanopterus are Palearctic species, which adapted to the cold environment and had been completely extinct in the study area since the Holocene Megathermal period. Based on the analyses of paleozoogeography and paleoecology of these four species, it could be concluded that the Yumidong Cave area was dominated by subalpine evergreen coniferous forest or coniferous and broad-leaved mixed forest during MIS 2 and MIS 4 periods, which were colder and had more coniferous forest than now, while the vegetation landscape of MIS 3 and MIS 5 periods were similar to that of nowadays.