NEW DATA ON THE SKULL AND DENTITION IN THE MONGOLIAN LATE CRETACEOUS EUTHERIAN MAMMAL ZALAMBDALESTES

Abstract

Abstract Exquisitely preserved specimens of the Late Cretaceous eutherian Zalambdalestes recently collected from the Djadokhta Formation (Early Campanian) of the Gobi Desert by the Mongolian Academy of Sciences–American Museum of Natural History Expeditions are the centerpiece of a thorough redescription of this taxon's craniodental morphology. Resolved and amended are uncertainties and errors in prior descriptions based on poorer preserved specimens collected by earlier expeditions to the Gobi. Preserved and described for the first time in Zalambdalestes is the basicranium, including an ectotympanic bone and portions of the hyoid arch. Zalambdalestes with a skull length of nearly 50 mm is large compared with other Cretaceous eutherians. It is also highly specialized with a long, thin, tubular snout, large diastemata in the anterior upper dentition, and an elongated mesial lower incisor with restricted enamel. These specializations, though less extreme, are also present in the zalambdalestids Barunlestes ...