New material of dipodid rodents (Dipodidae, Rodentia) from the early Miocene of Gashunyinadege, Nei Mongol, China

ABSTRACT

Dipodid rodent fossils from Gashunyinadege at ∼17 Ma, one of the oldest Neogene localities in central Nei Mongol, China, include six genera (Heterosminthus, Plesiosminthus, Litodonomys, Sinodonomys, gen. nov., Omoiosicista, gen. nov., and Sicista) and nine species, including four new species (P. vegrandis, sp. nov., L. minimus, sp. nov., S. simplex, sp. nov., and O. fui, sp. nov.). The high diversity and abundance of dipodid rodents in Gashunyinadege indicate the evolution of basal dipodids was centered in Nei Mongol. Omoiosicista is described on the basis of eight isolated teeth and characterized by possessing one autapomorphy. This new taxon shares seven synapomorphies with Sicista, suggesting Sicista is the closest relative.

ACKNOWLEDGMENTS

I express my deepest gratitude to Z.-D. Qiu for exceptional opportunities he has given me and important comments on the manuscript. I sincerely thank W.-Y. Wu for allowing us to access to undescribed specimens of Litodonomys, B.-Y. Wang for valuable discussion of early dipodids, and R. Beaver for taking SEM images of specimens. This article reports a part of my Master's thesis at Southern Methodist University, advised by L. Jacobs, Y. Tomida, D. Winkler, and A. Winkler, to whom I greatly appreciate. I am grateful to X.-M. Wang and Q. Li who taught me their field technique. Comments by H. de Bruijn, A. V. Lopatin, and R. Asher greatly improved the manuscript. I thank de Bruijn for sharing his contribution to the Neogene of the Old World database regarding Dipodidae with me. Financial support was provided by the Institute for the Study of Earth and Man, the Geological Society of America, the Graduate Student Assembly of Southern Methodist University, and the Municipal Museum of Mikasa, Hokkaido.