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Everyone knows that birds come down from dinosaurs, but the way this has happened is the subject of many studies and debates. To help clear things up, these researchers went ahead and immediately built a robotic dinosaur to test their theory: these proto-birds flapped their wings long before they flew.
Now, it's not a hyper-controversial position or anything. When you think about it, it's quite reasonable: natural selection tends to focus on existing features rather than inventing them from scratch. If these creatures, for example, had gone from quadrupeds to bipeds and had a few extra limbs up front, it would be logical for these members to become useful in a few million years.
But when did this start and how? To investigate, Jing-Shan Zhao of Tsinghua University in Beijing examined an animal called Caudipteryx, a terrestrial animal with "feathered forefeet that can be considered" proto-wings ".
Based on the well-preserved fossil record of this bird-dinosaur cross, the researchers estimated a number of physiological parameters, such as the maximum speed of the creature and its rhythm. From this, they could estimate the forces exerted on other parts of the body – just as anyone who studies a human jogging could say that such and such a joint is subjected to such or such degree of stress.
What they discovered was that, theoretically, these "natural frequencies" and Caudipteryx body biophysics would cause its tiny baby wings to flap up and down, evoking a real flight. Of course, they would not provide any lift, but this natural rhythm and movement may have been the seed that has grown over generations to become something bigger.
To give some strength to this theory, the researchers then built a pair of unusual mechanical elements: a pair of Caudipteryx wing replicas for a juvenile ostrich, and a robotic dinosaur imitating the original's gait. A little whimsical, of course – but why would not science become a little crazy from time to time?
In the case of the ostrich backpack, they literally just built a replica of the dinosaur wings and attached it to the bird and then made it run. The sensors on board the aircraft checked what the researchers observed: the natural flapping of the wings following the movements of the body and the vibrations of the feet touching the ground.
The robot is a full size reconstruction based on a complete animal fossil made of 3D printed parts, on which the fantastic wings of the ostrich could also be affixed. The theoretical model of the researchers predicted that the beat would be more pronounced when the bird's speed was around 2.31 meters per second – and this is exactly what they observed in the stationary model imitating gaits corresponding to different velocities. race.
You can see another gif on the Nature blog. As the researchers summarize:
These analyzes suggest that the impulse of the evolution of motorized flight in the line of theropods leading to Aves could have been a completely natural phenomenon produced by bipedal movement in the presence of plucked forelimbs.
How legitimate is it? Well, I'm not a paleontologist. And an ostrich is not a Caudipteryx. And the robot is not really convincing to watch. We will let the scientific community judge this document and its evidence (do not worry, it has been reviewed by peers), but I find it fantastic that researchers have chosen this path to test their theory. A few years ago, that kind of thing would have been a lot harder to do, and although it sounds a little silly when you look at it (especially in gif form), there is a lot to be said for this kind of real DIY when there is so much science in computer simulations.
The document was published today in the journal PLOS Computational Biology.
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