Taphonomy and biochronology of the Late Pleistocene mammalian fauna at Baolai cave, in Bubing Basin, southern China

This paper reports a mammalian fauna collected from the excavation of Baolai cave, southeast of Bubing Basin, in 2004. The fauna mainly consists of extant species and only a few typical members of 'Ailuropoda-Stegodon fauna' (Stegodon, Ailuropoda and Rhinoceros). According to results of the U-series dating from flowstones overlying and below the fossil beds (54-24 Ka), the Baolai fauna represents the mammalian assemblage in the Late Pleistocene. Compared with the faunas of Middle and Late Pleistocene in southern China and Southeast Asia, extant species dominate the Baolai fauna, mostly consistent with modern fauna of southern China during the Holocene. Modern fauna emerged later in southern China than in Southeast Asia, presenting successive characteristics. Significant bias for small or tiny fossils in Baolai cave reveals a special taphonomic process. Baolai cave is located at the same horizontal level as Upper Wuyun cave and Ganxian cave which yield Middle Pleistocene deposits with mammalian fossils. However, the Baolai fauna is much younger. Based on the gnawing marks on tooth roots, rodents may be the main taphonomic agent, or the fossils were brought in by flow-water through the karstic system above.