CRICETID RODENTS FROM THE EARLY MIOCENE XIACAOWAN FORMATION, SIHONG, JIANGSU

This paper describes the cricetid material collected from the Xiacaowan Formation at Sihong, Jiangsu Province in the 1980s. The cricetid assemblage consists of 5 species and 5 genera, including 1 new genus and 4 new species. These hamsters are assigned to 4 subfamilies of Cricetidae, e.g. Alloeumyarion sihongensis gen. et sp. nov. of Eumyarioninae, Cricetodon wanhei sp. nov. of Criceto-dontinae, Primus pusillus sp. nov. and Democricetodon suensis sp. nov. of Copemyinae, and Megacricetodon sinensis Qiu et al., 1981 of Megacricetodontinae. The assemblage represents the most diverse and abundant group of mammals in the Sihong Fauna, having 3 genera (Cricetodon, Democricetodon and Megacricetodon) in common with some Early/Middle Miocene faunas of northern China, as well as Europe and West Asia, sharing Primus, Democricetodon and Megacricetodon with Early/Middle faunas from Indian Subcontinent. The new genus Alloeumyarion shows affinities with Eumyarion of Europe and western Asia. The cricetid community, occurring in the modern "Transitional Zone" of zoogeographic regions between the Oriental Region and the Palaearctic Region, provides evidence for the study of Miocene zoogeographic provinces. This association argues for an age of Early Miocene for the Xiacaowan Formation, corresponding to Shanwangian of Chinese Land Mammal Age, or correlated, in European terms, with MN4.