Tuesday 20 March 2018

Hollow bones helped high-flying reptiles stay aloft

John von Radowitz

A super-efficient breathing system and hollow bones helped the largest animals that ever flew stay in the air, new research has shown.

Scientists have long been puzzled by the flying ability of pterosaurs, bird-like reptiles which lived alongside the dinosaurs and grew to the size of light aircraft.

Evidence suggests they flapped their wings like birds -- but some appeared simply too big for that to be possible.

Now a new study may have solved the riddle. The research suggests that the ancient dragons breathed via an intricate system of air sacs branching out from the lungs into many of their bones. The "pneumatised" skeletal system would have allowed them to obtain enough oxygen to meet the enormous energy requirements of flight.

In addition, the hollow bones would have reduced the creatures' weight and helped them get airborne.

Similar design features exist in modern birds, which evolved them independently, say the scientists.

Dr David Unwin, a palaeobiologist at the University of Leicester, together with US colleagues, took an in-depth look at pterosaur fossils and bird skeletons using computerised tomography (CT scans) normally employed in hospitals.

The x-ray scans, which build up detailed 3D images from a series of cross-sectional "slices", revealed air sac cavities in many pterosaur bones extending all the way to the wing tips.

One well preserved specimen also revealed that pterosaurs had mobile rib cages, which would have assisted flight.

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