A giant tooth from the Late Cretaceous (middle Campanian–lower Maastrichtian) of Patagonia, Argentina: An enormous titanosaur or a large toothed titanosaur?
Introduction
Titanosaurs are a group of herbivorous dinosaurs that comprise nearly half of all sauropod genera. This group of neosauropods developed a highly specialized dentition that could be related to a distinct and specialized feeding behavior (Calvo, 1994; García and Cerda, 2010a). The numerous cylindrical chisel-like teeth, with acute wear facets allow to infer a specialized mechanism of consumption of plant material. The titanosaur dentition restricted to the front of the snout is practically constant (Pm 4, M 7–8/D 10–13), not only among different taxa, but also with respect to its ontogeny (García and Cerda, 2010a, b; García et al., 2010). Despite its morphological specialization and its large tooth development (four replacement teeth and several generations of teeth) their dentition and the feeding mechanisms are poorly understood.
In this paper, the biggest titanosaur tooth yet discovered is described. This record sheds light on titanosaur diversity, at least with respect to skull and dentition size.
Section snippets
Geological context
The unit that yielded the tooth is the Allen Formation, whose age was estimated by Ballent (1980) as middle Campanian–lower Maastrichtian. This geologic unit is widely exposed at Río Negro and Neuquén Provinces but the quarry of the MML-PV 1030 teeth is in Salitral de Santa Rosa area, approximately 120 km west from Lamarque city, Río Negro Province.
Systematic paleontology
Dinosauria Owen, 1842
Saurischia Seeley, 1888
Sauropoda Marsh, 1878
Titanosauria Bonaparte and Coria, 1993
Gen. et sp. Indet.
Fig. 1, Fig. 2A, B
Description
The MML-PV 1030 tooth (Fig. 1A) is a cylindrical and thick chisel-like tooth, bearing a slight lingual curvature. Its total length is 75 mm. though the base of the root is incomplete. The dental crown length is 56 mm. The labial side is slightly more curved than lingual side, similarly to that of other titanosaur tooth (Kellner, 1996; Upchurch, 1998; García and Cerda, 2010a). The crown has the margins mesiodistally parallel, one of the main differences with the mesiodistally expanded crown of
Discussion and conclusion
The largest titanosaur tooth that has been reported is the second upper left tooth of Nemegtosaurus mongoliensis Nowinski (Wilson, 2005). The MML-Pv 1030 tooth is 32% greater in length, 9.1% greater mesiodistally and 40% greater labiolingually than that of the Asian taxon. Meanwhile with taxa as Rapetosaurus, Tapuiasaurus, Pitekunsaurus, Petrobrasaurus and Bonitasaura the difference is 38–46% greater in length (Curry Rogers and Forster, 2004; Zaher et al., 2011; Filippi and Garrido, 2008;
Acknowledgments
Funds from The Jurassic Foundation (to the Author) provided financial support for different aspects of the research. I gratefully acknowledge the logistics assistance of the Daniel Cabaza and Museo Municipal de Lamarque. María Soledad Fernandez, Julio Varela and Jose O'Gorman, are thanked for field support. Luis M. Chiappe and Sebastian Apesteguía substantially improved this work with useful comments and critical reviews.
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Histology of teeth and tooth attachment in titanosaurs (Dinosauria; Sauropoda)
2016, Cretaceous ResearchCitation Excerpt :However, compared to mammals, the teeth of titanosaurs and most reptiles (except some crocodylomorphs; e.g.O'Connor et al. 2010) are simple in terms of external morphology, and are generally less diagnostic. As with all sauropods dinosaurs, titanosaurs were a group of obligate herbivorous dinosaurs (Calvo, 1994; D'Emic et al. 2013; Sereno & Wilson, 2005; Upchurch & Barrett, 2000), with particular dentitions (morphologies, dental compositions, tooth replacement rate) that probably reflect specialized adaptations to their modes of feeding (Díez Díaz et al. 2012; García, 2013; García & Cerda, 2010a; Nowinski, 1971). Although, their tooth implantation has always been regarded as thecodont (i.e. an attachment type whereby teeth are placed within a socket by a complex of tissues including cementum, periodontal ligament, and alveolar bone; Gaengler, 2000), this claim has only been superficially justified at the histological level.