A New Giant Titanosauria (Dinosauria: Sauropoda) from the Late Cretaceous Bauru Group, Brazil.

Kamila L N Bandeira,Felipe Medeiros Simbras,Elaine Batista Machado,Alexander W A Kellner,Gustavo R Oliveira,Diogenes De Almeida Campos,Ulrich Joger

doi:10.1371/journal.pone.0163373

Kamila L N Bandeira, Felipe Medeiros Simbras + Show 5 more

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https://doi.org/10.1371/journal.pone.0163373

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Abstract

Titanosaurian dinosaurs include some of the largest land-living animals that ever existed, and most were discovered in Cretaceous deposits of Argentina. Here we describe the first Brazilian gigantic titanosaur, Austroposeidon magnificus gen. et sp. nov., from the Late Cretaceous Presidente Prudente Formation (Bauru Group, Paraná Basin), São Paulo State, southeast Brazil. The size of this animal is estimated around 25 meters. It consists of a partial vertebral column composed by the last two cervical and the first dorsal vertebrae, all fairly complete and incomplete portions of at least one sacral and seven dorsal elements. The new species displays four autapomorphies: robust and tall centropostzygapophyseal laminae (cpol) in the last cervical vertebrae; last cervical vertebra bearing the posterior centrodiapophyseal lamina (pcdl) bifurcated; first dorsal vertebra with the anterior and posterior centrodiapophyseal laminae (acdl/pcdl) curved ventrolaterally, and the diapophysis reaching the dorsal margin of the centrum; posterior dorsal vertebra bearing forked spinoprezygapophyseal laminae (sprl). The phylogenetic analysis presented here reveals that Austroposeidon magnificus is the sister group of the Lognkosauria. CT scans reveal some new osteological internal features in the cervical vertebrae such as the intercalation of dense growth rings with camellae, reported for the first time in sauropods. The new taxon further shows that giant titanosaurs were also present in Brazil during the Late Cretaceous and provides new information about the evolution and internal osteological structures in the vertebrae of the Titanosauria clade.

Highlights

Titanosaurs are considered a cosmopolitan group of dinosaurs and represent one of the most abundant and diverse clade within Sauropoda [1, 2]
The specimen Museu de Ciências da Terra (MCT) 1628-R represents a new sauropod dinosaur from Brazil, named here Austroposeidon magnificus gen. et sp. nov. It can be classified within Titanosauria based on the lack of hyposphene-hypanthrum, single neural spine of the cervical and dorsal vertebrae and the camellate internal structure. It can be separated from all other titanosaurs by several autapomorphies, which include the columnar-like centropostzygapophyseal laminae in the last cervical vertebrae and the presence of a bifurcated posterior centrodiapophyseal lamina
The new species comprises the largest dinosaur known from Brazil so far, with an estimated length from head-to-tail of around 25 meters

Summary

Introduction

Titanosaurs are considered a cosmopolitan group of dinosaurs and represent one of the most abundant and diverse clade within Sauropoda [1, 2]. The record of those dinosaurs has increased greatly in recent decades, in South America due to discoveries made in Argentina and Brazil (e.g., [3,4,5,6,7,8]). Regarding South America, Brazil and Argentina show a similar dinosaur fauna during the Late Cretaceous [26, 27]. There are nine recognized titanosaur species from Brazil, one from the Early Cretaceous Areado Group (Sanfranciscana Basin; Tapuiasaurus macedoi Zaher et al, 2011) and eight from the Late Cretaceous Bauru Group (Paraná Basin; Gondwanatitan faustoi Kellner & Azevedo, 1999; Trigonosaurus pricei Campos et al, 2005; Baurutitan britoi Kellner et al, 2005; Maxakalisaurus topai Kellner et al, 2006; Adamantisaurus mezzalirai Santucci and Bertini, 2006; Uberabatitan ribeiroi Salgado and Carvalho, 2008; “Aeolosaurus” maximus Santucci and Arruda-Campos, 2011, and Brasilotitan nemophagus Machado et al, 2013)

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