Late Middle Pleistocene micromammals of the Bianfudong paleolithic site, Heqing, western Yunnan

Abstract

Bianfudong (pinyin for Bat Cave) is a paleolithic site that was recently discovered in Heqing, Yunnan in southwestern China. Several hominin fossils, stone artifacts and more than 69,000 mammal fossils were unearthed in 2019. The hominin fossils and stone artifacts were excavated from the upper part (layers 1–12) of the section with an age range of 180–70 ka BP. Some large mammal fossils and micromammalian remains were collected from the lower part of the section (layers 22–30), which has an age >180 ka BP. This paper describes the micromammalian fossils collected from layers 25–30 and analyzes the fauna composition and paleohabitats. A total of 638 micromammal specimens represent 12 species, including 11 extant species i.e. Euroscaptor longirostris, Blarinella wardi, Anourosorex squamipes, Crocidura vorax, Eothenomys (Anteliomys) chinensis, E. (A.) proditor, Apodemus chevrieri, Ap. draco, Ap. latronum, Micromys minutus, and Niviventer confucianus, and one extinct species Anourosorex qianensis. The two arvicolid Eothenomys species dominate, both in the number of identified specimens and the minimum number of individuals. The composition of the Bianfudong micromammalian fauna can be compared with the faunas of Sanjiacun in Chenggong of Yunnan Province, Mawokoudong in Bijie and Xinglongdong in Fengjie, Guizhou Province. Using the random forest model with modern meteorological data, we calculated the mean annual precipitation (MAP) and the mean annual temperature (MAT) for all 11 living species in the Bianfudong. The MAP was inferred as 1008.04 mm, close to modern data in the Heqing area, while the MAT was slightly lower at 12.84 °C. The dominance of Eothenomys also supports a slightly cooler climate during the late Middle Pleistocene in the Heqing area.