The flight of the dinosaur
The pterosaurs were probably the first flying vertebrates, and evolved from an early line of thecodonts. Although pterosaurs were not ancestral to birds they did share some traits that indicate similarities in anatomy and physiology such as hollow bones. In addition, both bird and pterosaur skulls have relatively larger cerebellar and optic lobe capacities than the skulls of modern reptiles. Many of the earlier pterosaurs were small animals not even as large as crows. However, pterosaurs of the late Jurassic and Cretaceous periods grew to be the largest ever flying animals. Pteranodon had a 7 metre wingspan and a weight of ca. 17 kg, and the discovery of fossilized fish within their fossilized ribs, indicated that they must have flown great distances over water. What is difficult to explain is how they kept from crumpling their wings if they splashed into the water after prey, and even more difficult to understand how such large animals regained altitude. One suggestion is that they scooped up fish pelican-fashion and soared on ocean breezes. Even so, the lack of a stabilizing tail and the position of the wings behind the centre of gravity made them aerodynamically unstable. The rudderlike head may have provided some lateral stability, but other pterosaurs such as the largest Quetzalcoatlus (which had a wingspan of 16 metres and a weight of 65 kg) were even more unbalanced and lacked such stabilizing devices. Flight in Quetzalcoatlus has been compared to shooting an arrow backwards, even so this large beast must have had some means of contolling its flight since it evidently feed on the carcasses of other dinosaurs.