Pterosaur Wings With a Rib Cage to Match
Modern birds sustain their flight with an efficient ventilation system that keeps air flowing to their muscles. But no one knew how pterosaurs, the first flying vertebrates, powered their wings. A new study in PLoS One concludes that ancient pterosaurs, flying reptiles that lived 220 million to 65 million years ago, did much the same, with a mobile rib cage and a system of air sacs distributed throughout the bones to help move air around.
Pterosaurs dominated the sky in the Mesozoic era. The reptiles ranged from sparrow-sized peewees to giants with the wingspan of a small airplane. Although pterosaurs and birds share very distant reptilian ancestors, pterosaurs were not birds. As a result of studying the reptiles’ wing anatomy, scientists have long been confident that they flew by actively flapping—those wings weren’t meant for gliding. But how did pterosaurs get enough energy to power those muscles and stay in the air? “When we think of reptiles, we think of animals that literally creep along the ground and are relatively sluggish,” says paleontologist David Unwin of the University of Leicester in the United Kingdom. “If you take a crocodile or lizard and put wings on them, they would very quickly run out of energy to flap,” because flapping takes enormous effort.