杏吧原创

NOW we know how pterosaurs could once rule the skies. The biggest animals ever to fly had super-efficient bird-like lungs.

Leathery-winged pterosaurs evolved 220 million years ago from the same group of reptiles that gave rise to crocodiles and, later, birds. How the animals with 10-metre wingspans powered their flight had been a mystery because they were thought to have inflexible ribcages, which would have made their breathing too inefficient for such exertion.

at the College of the Holy Cross in Worcester, Massachusetts, realised this view might be mistaken after pterosaur specialist at the University of Leicester, UK, showed him a pterosaur fossil that suggested a 鈥渕obile ribcage鈥�. Further fossils confirmed it.

What鈥檚 more, the fossils revealed that the hollow bones contained air sacs linked to the dinosaur鈥檚 lungs. As in birds, such sacs would have passed air back and forth through the lungs, extracting oxygen more efficiently than in mammals.

Intriguingly, the sacs were connected to a pneumatic system under the skin, which pterosaurs might have been able to inflate to adjust their wing shape, Claessens says.