Gomphotheres from Linxia Basin, China, and their significance in biostratigraphy, biochronology, and paleozoogeography

Gomphothere proboscideans are abundant in the Early to Middle Miocene deposits in Linxia Basin, China, and are a biostratigraphically informative group. We review the gomphothere fauna of Linxia Basin, and report three fossil assemblages of different ages. Of these, the lowermost Gucheng assemblage (∼19–17 Ma) is represented by “Choerolophodon” guangheensis, “Protanancus” brevirostris, Gomphotherium cf. G. angustidens, and G. inopinatum, and is comparable to an assemblage from the upper member of the Chitarwata Formation, South Asia (∼20–18 Ma), and Wadi Moghara, North Africa (∼18–17 Ma). The middle Shinanu assemblage is represented by “Pr.” wimani, Platybelodon tongxinensis, and G. tassyi (∼17–15 Ma), and is similar to Early/Middle Miocene boundary faunas from West Asia and East Africa such as Maboko, Loperot, and Belometchetskaja (ranging ∼17–15 Ma), but also differs (choerolophodontids are absent, and Protanancus and Platybelodon coexist). The highest Zengjia–Laogou assemblage in the Middle Miocene (∼15–13 Ma) is characterized by Pl. grangeri and G. tassyi, and is unique in the predominance of Platybelodon, which is otherwise almost confined to northern China during this age (although some congeners also occur in the slightly later (∼13–11 Ma) Clarenodonian of North America (Pl. barnumbrowni and the G. productum complex)). Comprehensive study of gomphotheres from Linxia Basin improves our understanding of proboscidean evolution and migration during the Early and Middle Miocene across the Northern Hemisphere, and relevant northern China biostratigraphy.