New Material of the Zalambdalestid Zhangolestes (Mammalia, Zalambdalestidae) from the Late Cretaceous Changchunsaurus Fauna of Jilin, China

We report new material of the zalambdalestid, Zhangolestes jilinensis, from the Quantou Formation (lower Upper Cretaceous, Cenomanian to Turonian), Gongzhuling City, Jilin Province, NE China. Using micro-CT-scan, the material is shown to include dentocranial and postcranial elements recovered from the same matrix block containing the holotype specimen. The CT-images also show the labial and internal structures of the holotype fragment of the lower jaw of Z. jilinensis. Based on the preservation, relative size, and tooth wear, the new material and the holotype lower jaw likely belong to the same individual animal, whereas the hypodigm mandibular fragment assigned to Z. jilinensis in the original study is thought now to belong to a different individual, potentially representing a different species, which, if true, would increase the eutherian diversity in the Late Cretaceous Changchunsaurus Fauna. Furthermore, the new CT-images show that the incisor morphology is diverse within zalambdalestids and probably evolved independently from the enlarged incisors in placental mammals, such as Glires.