THE CRANIAL MORPHOLOGY OF AN EARLY EOCENE DIDYMOCONID (MAMMALIA, INSECTIVORA)

An early Eocene didymoconid skull with perfect basicranial region from Hubei Province of China is described. Important cranial features incl ude a small orbit, a broad temporal region, a maxilla-frontal contact in the orbit, absence of the jugal-lacrimal contact, a broad dorsal pr ocess of the alisphenoid, an extensive squamosal, absence of the postg lenoid foramen, a transversely elongate glenoid fossa, a fully ossifie d bulla, an external auditory canal floored by the squamosal and masto id of the petrosal, a greatly expanded mastoid of the petrosal, and a large foramen for the epitympanic sinus in the tympanic roof. In addit ion, the internal carotid artery may be reduced, although the stapedia l artery is well developed. Analyses of the cranial features reveal th at this skull is already highly specialized. The analyses also indicat e that the North American genus Wyolestes and the Asiatic didymoconids form a paraphyletic group and that derivation of both Wyolestes and d idymoconids from a Paleocene Yantanglestes-like mesonychid is not supp ortable. Instead, on the basis of cranial evidence, a didymoconid-inse ctivore relationship is suggested.