Time for Giants: Titanosaurs from the Berriasian–Santonian Age

GALLINA, P. A.; GONZÁLEZ RIGA, B. J.; ORTIZ, H.

South American Sauropodomorph Dinosaurs

Springer Nature

Año: 2022; p. 299 - 340

Titanosaurian sauropods were the most diverse and successful groupof large-bodied terrestrial herbivores. Two aspects regarding their evolutionaryhistory stand out, namely their great morphological diversity and their extensiverecord from various continental masses. In South America, and particularly inArgentina, the group has the richest record worldwide. This is mainly due to theconjunction of two factors: the extensive paleontological investigation carried outby South American researchers since the beginning of the twentieth century andthe well-exposed outcrops of Cretaceous continental strata. With the exception ofTapuiasaurus from Brazil, the entire record of South American named titanosaursdiscovered in the Berriasian–Santonian interval comes from Argentina, specificallyfrom Patagonia, including the south of Mendoza, Neuquén, Río Negro, andChubut Provinces. With a number of 22 valid taxa, the Early and ‘Mid’-Cretaceoustitanosaur record of South America includes basally branching (‘basal’) forms (e.g.,Andesaurus, Ninjatitan), basal and derived lithostrotians (e.g., Sarmientosaurus,Tapuiasaurus, and Epachthosaurus), and most of the colossosaurs (mainly the giantlognkosaurs Mendozasaurus, Futalognkosaurus, Patagotitan, and Notocolossus).After their origin in the Early Cretaceous, titanosaurians experienced a rapid increasein taxonomic diversity, which is maintained toward the Late Cretaceous. However, during the Berriasian–Santonian interval, the size of titanosaurs reached its climax,representing the largest vertebrate animals ever to inhabit the earth. Some SouthAmerican titanosaurs from this time have been widely used to define new clades(e.g., Colossosauria, Lognkosauria, Rinconsauria) that clarified the main phylogeneticrelationships at lower level. Moreover, studies in some key paleobiologicalaspects related with the estimation of size contributed to better understanding thebiology of some species in the context of the process of gigantism.