The osteology of Matutinia (Simplicidentata, Mammalia) and its relationship to Rhombomylus

Abstract New dental, cranial, and postcranial specimens of the eurymylid Matutinia nitidulus from the early Eocene Lingcha Formation, Hengyang Basin, Hunan Province, China, are described. These materials are among the best of basal gliroid mammals from Asia. Matutinia is similar to Rhombomylus in general tooth and cranial morphologies, including an expanded hypocone shelf on the upper cheek teeth and a complex zygomatic arch. These features distinguish the two genera from other eurymylids such as Heomys and Eurymylus. Matutinia differs from Rhombomylus in having lower crowned and less lophate cheek teeth, fewer bony septa in the mastoid chamber, a lower promontorium, and a carotid foramen in the ear region. Based on the new material, we consider Matutinia a valid genus, not a junior synonym of Rhombomylus.