1. Small Mammal Exploration in Yushe Basin, Shanxi Province

Yushe Basin is an intermontane basin at the eastern edge of the Loess Plateau in northern China. Its fluvial, lake and superposed loess deposits accumulated during the last 7 myr and contain many fossiliferous horizons. Small mammal fossils occur throughout, and some fossil horizons produce diverse assemblages that appear to faithfully represent the micromammal component of Yushe paleocommunities. Yushe Basin includes assemblages that represent the late Baodean age (latest Miocene) microfaunas of North China, and document contrasting younger assemblages that characterize a distinct Pliocene Yushe chronofauna. Pliocene fossils represent two successive microfaunas that distinguish the Gaozhuangian and Mazegouan land mammal stage/ages. These are in turn distinct from the Pleistocene assemblages of Yushe that correlate with Nihewan and later faunas. The Sino-American project, especially in the interval of 1987–1991, developed the small mammal biostratigraphy of the Yuncu subbasin of Yushe Basin. Small mammal fossils occur in every Yuncu formation, from the Baodean age Mahui Formation, through the Pliocene Gaozhuang and Mazegou formations, to the early Pleistocene Haiyan Formation. Important elements of later Pleistocene faunas occur in overlying loess. Field teams collected specimens exposed on eroded surfaces and followed indications of small mammal concentrations to excavate bulk samples and process them for fossils by wet screening. Wet screening revealed a rich component of micromammal diversity to complement the wealth of larger species that previously had been known as surface finds.