ABSTRACT

Here we report a new cricetid s.l., Caecocricetodon yani, gen. et sp. nov., discovered in the early Oligocene of the Caijiachong Formation in Yunnan Province, China. The new cricetid differs from all known cricetids or stem muroids by its particular molar pattern displaying numerous crests and spurs. Our phylogenetic analysis based on a matrix including 42 taxa and 72 characters indicates that the new species has a close relationship with Paracricetodontinae, forming a monophyletic clade with Paracricetodon and Trakymys. The new cricetid also has a likely close relationship with Pappocricetodon. However, the genus Pappocricetodon is polyphyletic in our analysis. Considering the similarity of the brachydont lophodont teeth of Caecocricetodon and glirids, we propose that the new species underwent convergent evolution with dormice, possibly adapting to an arboreal ecological niche in Oligocene of southern China.