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| Thanos simonattoi
Delcourt & Iori, 2019
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ABSTRACT
Abelisaurid theropods are well-know from the Cretaceous of several parts of the Southern Hemisphere, including South America, Madagascar, and Africa, but also in India and Europe. Abelisaurids are high-diverse among other theropods with several cervicocephalic specializations reaching medium/large sizes. In the present contribution, we describe a new abelisaurid (Thanos simonattoi, gen. et sp. nov.) from the São José do Rio Preto Formation, Bauru Group, Brazil (Upper Cretaceous). Thanos differs from other theropods by having a well-developed keel becoming wider and deeper posteriorly on the ventral surface; two lateral small foramina separated by a relative wide wall on each lateral surface of the centrum, and well-developed and deep prezygapophyseal spinodiapophyseal fossae. The closed sutures between the axis and odontoid suggest that Thanos had reached a subadult/adult stage before death. Thanos is phylogenetically related to Brachyrostra abelisaurid. The keel on the ventral axial centrum in abelisauroids is here interpreted as a homoplastic condition that became more pronounced towards the phylogeny. The presence of well-developed keel in Thanos suggests that this taxon could be more derived than other abelisaurids. Finally, even though abelisaurids could reach large sizes, Thanos shared the environment with a larger theropod that was probably close to Megaraptora.
KEYWORDS: Theropods, Brachyrostra, vertebra, axis, Thanos simonattoi
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| Figure 4. An interpretative picture of the paleoenvironment of São José do Rio Preto Formation (Santonian, Upper Cretaceous). The picture shows two specimens of Thanos simonattoi (on the right side) and titanosaur sauropods (on the mid and left sides).
Art by Deverson da Silva (Pepi).
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Systematic palaeontology
Dinosauria Owen, 1842
Theropoda Marsh, 1881
Ceratosauria Marsh 1884
Abelisauroidea Bonaparte and Novas, 1985
Abelisauridae Bonaparte and Novas, 1985
Brachyrostra Canale et al. 2009
Thanos simonattoi gen. et sp. nov.
Etymology: Genus name from the Greek thánato, meaning death and from the Marvel’s character Thanos, the Conquer, created by Jim Starlin. Species name in honor of Sérgio Simonatto, the discoverer of the specimen.
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In the present contribution, we have described a new abelisaurid from the São José do Rio Preto Formation, Upper Cretaceous of Brazil. Thanos simonattoi is distinguished from other abelisaurids by having a combination of features: a well-developed keel on the ventral surface becoming wider and deeper posteriorly; two lateral small foramina separated by a relative wide wall and two welldeveloped and deep prezygapophyseal spinodiapophyseal fossae. The keel on the ventral axial centrum of Thanos is interpreted as a homoplastic condition that became more pronounced towards the phylogeny, suggesting that this taxon could be more derived than other abelisaurids. The presence of a medium-sized abelisaurid in the São José do Rio Preto Formation increases the record of theropods, suggesting a complex carnivorous fauna during the Upper Cretaceous of Bauru Group. More findings are needed to better understand the morphology and the internal relationships of Thanos simonattoi.
Rafael Delcourt and Fabiano Vidoi Iori. 2019. A New Abelisauridae (Dinosauria: Theropoda) from São José do Rio Preto Formation, Upper Cretaceous of Brazil and Comments on the Bauru Group Fauna. Historical Biology: An International Journal of Paleobiology. DOI: 10.1080/08912963.2018.1546700
Méndez AH, Novas FE and Iori FV. 2014. New Record of Abelisauroid Theropods from the Bauru Group (Upper Cretaceous), São Paulo State, Brazil. Revista Brasileira de Paleontologia. 17(1). Citeseer: 23–32.
