On the occurrence of lateral openings and fossae (pleurocoels) in the thoracic vertebrae of neornithine birds and their functional significance

Abstract The occurrence of lateral openings and pleurocoels (lateral fossae) in the corpus thoracic vertebrae extant fossil neornithine birds is reviewed, with both features having been identified as osteological correlates avian pulmonary system. Openings mainly occur larger species a high overall bone pneumatization but do not seem to serve for passage lung or air sac diverticula. Pleurocoels, on other hand, are directly related pneumatic constitute plesiomorphic trait that was widespread Mesozoic non-neornithine birds. It noted an inverse correlation exists between humerus, being found taxa, which humerus pneumatized by diverticula clavicular sac. Here it hypothesized primarily increase structural resistance vertebral body were reduced multiple times In some their reduction may be development furcula, assists ventilation cervical sacs thereby contribute both, vertebrae. If so, birds, had rigid furcula massive shafts well non-pneumatic humeri pronounced pleurocoels, likely have differed functional aspects system from