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| Ibirania parva Navarro, Ghilardi, Aureliano, Díaz, Bandeira, Cattaruzzi, Iori, Martine, Carvalho, Anelli, Fernandes & Zaher, 2022 |
Abstract
Titanosaurian sauropods are known to exhibit remarkable body size disparity, with some taxa famed for nearing the zenith of terrestrial vertebrate body size. Here, we describe a new titanosaurian – Ibirania parva gen. et sp. nov. – from the Upper Cretaceous (Santonian–Campanian) São José do Rio Preto Formation of Bauru Basin, n which represents one of the smallest sauropods known to date. The new taxon is diagnosed by seven autapomorphies and had an estimated body length of 5.7 m. Histological and μCT scan analyses showed that this new taxon is represented by skeletally mature individuals, which had attained somatic maturity prior to death. Phylogenetic analyses recovered the new taxon deeply nested within Saltasaurinae, a clade previously known by small-sized forms. Ibirania parva gen. et sp. nov. brings new information indicating that the body size reduction in some titanosaurians could be driven by recurrent ecophysiographical settings, present in South America prior to the diversity peak attained by the group during the Campanian–Maastrichtian.
Keywords: Bauru Basin, Growth Patterns, Histology, Nanism, Saltasauridae, São José do Rio Preto Formation
Bruno A. Navarro, Aline M. Ghilardi, Tito Aureliano, Verónica Díez Díaz, Kamila L. N. Bandeira, André G. S. Cattaruzzi, Fabiano V. Iori, Ariel M. Martine, Alberto B. Carvalho, Luiz E. Anelli, Marcelo A. Fernandes and Hussam Zaher. 2022. A New nanoid titanosaur (Dinosauria: Sauropoda) from the Upper Cretaceous of Brazil. Ameghiniana. 59(5); 317-354. DOI: 10.5710/AMGH.25.08.2022.3477
