Quetecsaurus was diagnosed based on three autapomorphies, i.e. unique traits, by its describers. The intercentrum of its atlas shows a prominent anteroventral border and enlarged posteroventral processes. Its humerus is uniquely shaped, with strongly sigmoid (S-shaped) proximal border, rounded proximomedial border, and angular proximolateral corner. Like lognkosaur titanosaurs, it possess lateral expansions on the neural spines of its rear cervical vertebra, however they are incipient and relatively reduced.
Phylogeny
Quetecsaurus was assigned to the Titanosauria, and considered to be most closely related to Mendozasaurus and Futalognkosaurus, members of Lognkosauria, based on the presence of these lateral laminae on its neural spines. A preliminary phylogenetic analysis supported this assignment, placing Quetecsaurus as a sister taxon of the clade formed by Mendozasaurus and Futalognkosaurus.[1]
