Pneumatisation in a nanoid Saltasaurid Titanosaur from the Upper Cretaceous of western São Paulo State, Brazil.
[sciencythoughts.blogspot.com]
The Dinosaurs were (and are) and exceptionally diverse group of Animals, and developed a wide range of novel innovations over their long evolutionary history. One of these inovations was the pneumatisation of the post-cranial skeleton, a trait found in both Sauropods and Theropods (including the living Birds). In these Dinosaurs the axial skeleton is infiltrated by a system of diverticula (pouches) which derive from the lungs. Although the pneumatisation of the post-cranial skeleton has been known about in non-Avian Dinosaurs for a long time, the phenomenon has not been widely studied, as traditionally the only way to do this was through the observation of macroscopic structures, which could not usually be observed without cutting into the bone, and which were not always preserved anyway. More recently, the advent of computed tomography has enabled the non-destructive study of a wider range of bones, and led to a better understanding of the distinctive bone histologies associated with pneumatisation.