Pneumatization of an immature azhdarchoid pterosaur

• Description of the postcranial anatomy in a juvenile azhdarchoid pterosaur.
• Damage permits the calculation of air space proportions within the postcrania.
• Azhdarchoid pterosaurs have air space proportions similar to sauropod dinosaurs.
• Pneumatic invasions penetrate some of the smallest bones, even in young animals.
• Cortex thickness can be as low as 0.03 mm in pneumatic elements.

The partial skeleton of an immature azhdarchoid pterosaur from the Santana Formation (Early Cretaceous) of NE Brazil is described, where breaks across several of the three dimensionally preserved postcranial elements have permitted the thickness of the cortex to be accurately measured. Air-space proportions (ASP) are shown to be comparable to those observed in sauropod dinosaurs. The pterosaurian pneumatic system, prevalent throughout these animals, is shown to be well developed in even non-adult animals and is inferred to have penetrated into even the smallest of bones.