Variation in the postcranial pneumaticity in derived titanosaurs (Dinosauria: Sauropoda)

Abstract

Currently, only birds have a pneumatic system, but in the past, this was common among several ornithodirans.Within Titanosauria, it was the saltasaurines that showed a high degree of postcranial pneumaticity. Theobjective of this work is analysing the extent of postcranial pneumaticity in saltasaurines and compare it withother derived titanosaurs. To carry out this work, presacral vertebrae, dorsal ribs, scapulae, coracoids and iliaof saltasaurines were analysed. The presacral vertebrae present a high degree of pneumatisation witha highly variable distribution of foramina, with some ‘foramina zones’, there is a homoplastic pattern ofpneumaticity: presence of foramina connected to camellated tissue. With respect to the ilia, camellatedtissue was recorded in all taxa. Instead, scapulae and coracoids, present camellated tissue in Saltasaurus andthey cannot be pneumatised in Neuquensaurus. Comparing with other titanosaurs, we observe that there are‘foramina zones’ for presacral and caudal vertebrae. It is also possible to establish that the pneumatisation ofthe dorsal ribs has a conservative pattern, not only in saltasaurines but also in the Saurischia clade, and thepresence of pneumaticity in the ilia is frequent in the Lithostrotia and even outside, in rebbachisaurs.