A ZALAMBDODONT INSECTIVORE OF THE FAMILY APTERNODONTIDAE (INSECTIVORA, MAMMALIA) FROM THE MIDDLE EOCENE OF MONGOLIA

Abstract

A new Asian zalambdodont insectivore of the family Apternodontidae, Asiaptemodiis mackennai gen. et sp. nov., from the Middle Eocene of Mongolia (Khaychin Formation, Khaychin-Ula 2 locality) is described. In Asiaptemodiis, P4 is nonmolariform and the protocone on the upper molars is very large, clearly distinguishing the new genus from Oligoryctes and Aptemodus found in the Eocene-Oligocene of North America. Regarding the structure of the lower molars, Asiaptemodiis is most similar to Paraptemodus from the Lower Eocene of North America. The dental structure, relatively large zygomatic process of the maxilla, and the structure of the ascending ramus of the lower jaw suggest IhalAsiaptemodus is more primitive than the previously described North American apternodontids.