A primitive relative of rodents from the Chinese Paleocene

ABSTRACT

A new genus and species of basal gliriform mammal, Sinomylus zhaii, is described from the late Paleocene Tujinshan Formation of southern China. The new species is based on a fragmentary rostrum bearing a possible alveolus for a right PI (DPI) or C (DC), well-preserved left P3–M2, and broken incisors and other cheek teeth. There is one pair of upper incisors. The incisor enamel has one layer of radial enamel microstructures and lacks Hunter-Schreger bands. P2 is small and conical. Both P3 and P4 consist of two main cusps. The molars are unilaterally hypsodont and have the typical eurymylid tooth pattern. Collectively, these features place the new genus as the sister-taxon to the clade comprising eurymylids and rodents.