Skeletal pneumaticity

It is generally produced during development by excavation of bone by pneumatic diverticula (air sacs) from an air-filled space, such as the lungs or nasal cavity.

Examples include the hyoid in howler monkeys Alouatta, and the dorsal vertebrae in the osteoglossiform fish Pantodon.

[5] Slight pneumatization of the centra and rib heads by dorsal diverticula in the lungs of land tortoises has also been documented.

By invading the bones, the pneumatic diverticula would replace marrow with air, reducing the overall body mass.

[7] Pneumatizing the vertebral column of sauropods would reduce the weight of these organisms, and make it easier to support and move the massive neck.