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If we could take a peek at the Land of the late Jurassicinstead of today’s birds we would probably see the sky furrowed by pterosaurs, flying dinosaurs with wingspan from 25 centimeters to 10-11 meters depending on the species. But how could they get up in flight? It is a’age-old question which led to several hypotheses and simulations, all of them controversialbecause tracing the movements of extinct animals, with anatomical structures that have no analogues in current animals, always leaves a certain degree of uncertainty. Recently, however, an international team, led by Michael Pittman of the Chinese University of Hong Kong, presented on the pages of Scientific Reports an apparently more solid proposal: using a special imaging technique (called Laser-stimulated fluorescence, Lsf), scientists have unearthed, in the fossils of some small webbed-legged pterosaurs, the “imprint” left by the wing membrane and others soft tissue. These unpublished details they suggest how these animals could have moved and even take off from the water.
Like ducks
Those studied by Pittman and his colleagues are fossils of Aurorazhdarchoa genus of pterosaur from small size lived in the region that today corresponds to Bavaria, in southern Germany. These winged reptiles also had webbed pawsbut it was by no means certain that they were swimming on the surface of the water: there were no clues that would suggest that they were then able to get out of the water or soar from there.
As explained by a Ars Technica Mike Habib, expert in aeromechanics and aerodynamics at the National History Museum in Los Angeles, was the small size of the Aurorazhdarcho: for the small animals is harder take off from a body of water compared to those a little larger due to the greater surface of contact with the liquid. Smaller animals, in other words, need more strength to escape the surface tension. The details gleaned from the new study, according to Habib, provided the basis for saying that Aurorazhdarcho would have been able to take off from the water using all four limbs to push themselves out, as today they do domestic duckswithout resorting to extreme movements of the joints.
Flutter-proof wings
Thanks to the LSF technique, the researchers also identified the “actinofibrils “anatomical structures of support in the wing membrane and in the hind limb girdles of pterosaurs whose voluntary activation would have minimized the aeroelastic flutterthat is, that vibration which causes one uncontrolled flutter (like a flag at the mercy of the strong wind) which would make any flight a lot dangerous.
From dinosaurs to robots
To those wondering what can be used today to reconstruct the flight mechanics of extinct animals, the experts have the ready answer: robotics. The wings of pterosaurs and their ability to avoid flutter could, for example, be imitated by new prototypes of helicopters.
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