PNEUMATIC FOSSAE OF APATOSAURUS FROM THE MORRISON FORMATION

In the Mygatt-Moore Quarry of the Jurassic Morrison Formation near Grand Junction,CO, one of the most common dinosaurs found is Apatosaurus, a sauropod. Sauropods were some of the largest animals ever to walk the earth. They were so large, it is thought that they had vertebral pneumatic cavities, which may have helped lessen the skeletal weight or possibly have served a mechanical function like an avian lung. Pneumatic cavities are pockets of air in the vertebrae. Of the three basic types of pneumatic cavities, fossae, camera, and camella, the only one that can be seen and recorded from the outside are fossae. There have been studies of individual sections of the vertebral column, but very few, if any studies, encompass the entire column. My research focuses on how the pneumatic fossa varies from the cervical vertebrae of the neck, into the dorsal vertebrae of the body, and finally the caudal vertebrae of the tail. Of the 117 specimens viewed, nearly all of the vertebrae were disarticulated, probably indicating that the Apatosaurus vertebrae come from ~5 different specimens. Some results are that the fossae ofthe cervical vertebrae tend to be very large, with an average volume of 4408.7 cm³. The fossae of the dorsal vertebrae have an average volume of 1755.2 cm³. In contrast, the much smaller fossae of the caudal vertebrae have an average volume of 82.1 cm³. The variations in fossae size along the vertebral column suggest that the fossae were for reduction of skeletal weight.