Dental Morphology of Vintana Sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar
ABSTRACT—The cranium of Vintana sertichi preserves the first associated upper dentition of a gondwanatherian mammal. Gondwanatherians are known almost exclusively from isolated teeth, particularly molariforms. As such, referral of V. sertichi to the Gondwanatheria, differentiation of V. sertichi from other gondwanatherians, and determination of the relationships of V. sertichi to other gondwanatherians must rely heavily on dental morphology. The hypsodont nature, gross morphology, enamel microstructure, and wear pattern of its molariform teeth serve to unequivocally identify the cranium of V. sertichi as that of a sudamericid gondwanatherian. Based on available morphology, V. sertichi appears to have had an upper dental formula of 18.104.22.168. There are two long, curved alveoli in each premaxilla for enlarged, buccolingually compressed, procumbent incisors that were well separated from the cheek teeth by a long diastema. There is no evidence of a canine. The single premolariform tooth appears to have been small and two-rooted, but neither the left nor the right crowns are preserved. Of the eight upper molariform alveoli, four are preserved with teeth in situ, three in the left maxilla (antepenultimate, penultimate, and ultimate) and one in the right (penultimate). The molariform cheek teeth have several salient characteristics: large size, hypsodont crowns, roughly quadrangular outlines, occlusal surfaces worn essentially flat, numerous cementum-filled infundibula, cementum-filled furrows that invaginate from the buccal side but do not extend to the base of the crown, and multiple, short root apices. The relative amounts of wear on the molariform cheek teeth of V. sertichi indicate a mesial-to-distal eruption sequence.
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