New contributions to the presacral osteology of Saltasaurus loricatus (Sauropoda, Titanosauria) from the Upper Cretaceous of northern Argentina

Saltasaurus loricatus is a derived form of sauropod dinosaur from the Upper Cretaceous of northern Argentina. In this work, we expand the information of the presacral vertebral column of Saltasaurus loricatus, including a detailed description of neural laminae, fossae and pneumatic foramina of the neural arch, and establish a comparative analysis with closely related taxa (Neuquensaurus australis and Rocasaurus muniozi). Our data does not support previous phylogenetic hypothesis in which S. loricatus is more closely related to R. muniozi than N. australis. A conservative pattern of distribution of pneumatic foramina in the neural arch of cervical vertebrae cannot be recognized. Although variation in the pneumatic foramina distribution is also present in dorsal vertebrae, these structures are more commonly observed in certain regions (within the postzygapophyseal spinodiapophyseal fossa and spinoprezygapophyseal fossa + prezygapophyseal spinodiapophyseal fossa and in the dorsal border of the spinodiapophyseal lamina). Our data reveal that, despite its value in paleobiological and systematic studies, the presence and distribution pattern of pneumatic foramina in neural arches of presacral vertebrae appears to be underestimated in previous anatomical studies.