Dental Morphology of Vintana Sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar

Abstract

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 2.0.1.4. 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.

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

ACKNOWLEDGMENTS

I thank J. Groenke (Vertebrate Fossil Preparation Laboratory, Stony Brook University [SBU]) for expertly preparing the teeth and alveoli of UA 9972; J. Thostenson and M. Hill (AMNH Microscopy and Imaging Facility, New York) and J. Diehm and B. Ruether (Avonix Imaging, Plymouth, Minnesota) for providing outstanding and expert assistance in μCT scanning of UA 9972; S. Hoffmann, J. Nestler, and J. Groenke (Department of Anatomical Sciences, SBU) for countless hours of assistance with postprocessing of the μCT data sets; J. Groenke for information on scanning parameters; A. Pritchard for curatorial and other assistance; J. Neville (Media Services Division, SBU) for taking the photographs in Figures 1 and 2; P. O'Connor (Ohio University) and J. Groenke for assembling the two interactive 3D PDFs provided here as Supplemental Data; and L. Betti-Nash (Department of Anatomical Sciences, SBU) for reconstructing the molariform teeth digitally for Figure 2B, for drafting Figure 3, and for assistance in arranging and labeling the other figures. I also thank F. Goin (MLP), D. Pol (MPEFCH), and M. Pérez (MPEFCH) for providing comparative materials of Sudamerica and Gondwanatherium; G. Wilson (University of Washington) for providing casts of Bharattherium teeth; J. Groenke (SBU), S. Hoffmann (SBU), W. v. Koenigswald (Universität Bonn), J. Nestler (SBU), and J. Schultz (Universität Bonn) for discussion; and D. Croft and Y. Gurovich for insightful reviews of the submitted manuscript. This research was supported by grants from the National Geographic Society (8597-09) and the National Science Foundation (EAR-0446488, EAR-1123642).

Handling editor: Jeffrey A. Wilson.