How pneumatic were the presacral vertebrae of dicraeosaurid (Sauropoda: Diplodocoidea) dinosaurs?

This article focuses on the study of skeletal pneumaticity—the invasion of bone by air sacs—in the presacral vertebrae of two dicraeosaurid sauropods, Amargasaurus cazaui and Brachytrachelopan mesai. Using computed tomography (CT) scans, the researchers identified a 'procamerate' internal pneumatization pattern in these taxa, characterized by simple fossae penetrating the vertebral centra without complex internal branching, indicating a reduced degree of pneumaticity compared to other eusauropods. The study also notes that basal dicraeosaurids generally exhibit higher pneumaticity, with Pilmatueia faundezi showing the greatest degree among Gondwanan dicraeosaurids, while Amargasaurus, Brachytrachelopan, and Dicraeosaurus share similarly low levels of pneumatic invasion. These findings suggest that pneumaticity in dicraeosaurids correlates with their relatively smaller body size and shorter necks, and that cervical air sacs were present but did not extensively invade the vertebrae.