New lower jaw and teeth referred to Maxakalisaurus topai (Titanosauria: Aeolosaurini) and their implications for the phylogeny of titanosaurid sauropods.

Marco A.G França,Max C Langer,Douglas Riff,Júlio C De A Marsola,Annie S Hsiou

doi:10.7717/peerj.2054

Marco A.G França, Max C Langer + Show 3 more

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https://doi.org/10.7717/peerj.2054

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Abstract

Sauropod dinosaurs compose a diversified, well known, and worldwide distributed clade, with a stereotyped body plan: deep trunk, elongated neck and tail, columnar limbs and very small skull. In Brazil, the group is represented by ten formally described Cretaceous species, mostly titanosaurs. This is the case of Maxakalisaurus topai, known based on an incomplete and disarticulated skeleton, unearthed from deposits of the Adamantina Formation in Minas Gerais. Here, we report a partial right dentary, including five isolated teeth, collected from the same site as the type-series of M. topai and tentatively referred to that taxon. The bone is gently curved medially, the functional teeth are set on an anterolingual position, and two replacement teeth are seen per alveoli. New morphological data gathered from that specimen was employed to conduct a comprehensive phylogenetic analysis of Titanosauria (with 42 taxa and 253 characters), based on previous studies. The Aeolosaurini clade was recovered, with Gondwanatitan and Aelosaurus as sister taxa, and Maxakalisaurus, Panamericansaurus, and Rinconsaurus forming a basal polytomy.

Highlights

Sauropodomorpha is a clade of herbivorous dinosaurs that originated during the Late Triassic and were prevalent, both in diversity and biomass, in terrestrial biomes during the Middle-Late Mesozoic, with at least 175 valid taxa currently known (Young, 1951; Dodson, 1990; Galton, 1986; Langer et al, 1999; Barret & Upchurch, 2005; Martinez & Alcober, 2009; Mannion et al, 2011; Novas et al, 2011). them, Sauropoda is the most diverse clade, but the second most representative dinosaurian group - c. 18% of the non-avian dinosaur diversity (Curry Rogers & Wilson, 2005)
How to cite this article França et al (2016), New lower jaw and teeth referred to Maxakalisaurus topai (Titanosauria: Aeolosaurini) and their implications for the phylogeny of titanosaurid sauropods
The regions of alveoli 1–3 and 7–10 are straighter in dorsal/ventral view, whereas that of alveoli 4–6 holds the curvature. This morphology is similar to that seen in Brachiosaurus (Janensch, 1935–36), Euhelopus (Poropat & Kear, 2013),and Tapuiasaurus (Zaher et al, 2011), but somewhat different from that seen in Rapetosaurus (Curry Rogers & Forster, 2004) and Nemegtosaurus (Nowinski, 1971), in which the curvature is placed more posteriorly, encompassing alveoli 5–6, or in Brasilotitan, in which the dentary is L-shaped, with a right angle between the posterior and anterior regions (Machado et al, 2013)

Summary

Introduction

Sauropodomorpha is a clade of herbivorous dinosaurs that originated during the Late Triassic and were prevalent, both in diversity and biomass, in terrestrial biomes during the Middle-Late Mesozoic, with at least 175 valid taxa currently known (Young, 1951; Dodson, 1990; Galton, 1986; Langer et al, 1999; Barret & Upchurch, 2005; Martinez & Alcober, 2009; Mannion et al, 2011; Novas et al, 2011). them, Sauropoda is the most diverse clade, but the second most representative dinosaurian group - c. 18% of the non-avian dinosaur diversity (Curry Rogers & Wilson, 2005). Them, Sauropoda is the most diverse clade, but the second most representative dinosaurian group - c. Within Macronaria, Titanosauria represents the most speciose clade, corresponding to one of the most abundant Cretaceous dinosaur groups, successful in Gondwana, mainly in the South America mainland (Salgado, Coria, & Calvo, 1997; Wilson, 2002). The group includes early splits (e.g., Phuwiangosaurus) and the Lithostrotia lineage, including early splits and clades like Nemegtosauridae, Saltasaurinae, Opisthocoelicaudinae, and Aeolosaurini (Apesteguia, 2004; Wilson & Upchurch, 2003; Upchurch, Barrett & Dodson, 2004; Santucci & Arruda-Campos, 2011)

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