The best concepts prevail: This principle of evolution also shaped the development history of “animal aviation”. A study now shows that, in addition to the successful concepts, there were also rather inadequate “test models”: It attests that two dinosaurs with a bat-like wing design have poor flight abilities. Presumably, their construction plan was hardly competitive and therefore disappeared again after only a few million years. The results show, however, that the dinosaurs brought about different flight concepts before birds developed, say the scientists.
After the creatures of the earth had conquered the water and then the land in the course of evolution, it was finally the turn of the air: Animals from different lines of development produced body structures that enabled them to glide through the air or actively fly. It is well known that some of them have developed into true flight artists: Many birds, bats and insects have sophisticated aerodynamic designs that still serve as models for human flight technology today. There seem to be parallels between technical development and evolutionary processes: Concepts that are successful gain acceptance and form the basis for further developments. Other approaches, however, turn out to be inferior and disappear again.
Dinos with bat wings
As far as the evolution of birds is concerned, it is believed that they evolved from small two-legged dinosaurs, which, along with further adaptations to their arms, eventually produced more and more powerful wing structures with feathers. But there are still many unanswered questions about this process and the history of the “test models” on this path. In this context, an international team of researchers has now devoted itself to the study of two representatives of the mysterious group of dinosaurs the Scansoriopterygidae, which lived around 160 million years ago.
Previous studies have shown that Yi qi (“strange wing”) and Ambopteryx had fur-like plumage on their bodies, but that their wings were equipped with flight membranes. This concept is not known from other dinosaurs, but it is typical of the pterosaurs and bats. The research showed that Yi qi and Ambopteryx also had unusual bone structures in their wings that set them apart from other winged dinosaurs. It is believed that the approximately one kilogram animals lived in trees. So far, however, it was unclear what flight skills the unusual wing concept gave these animals.
The research team has now investigated this question using model simulations. Laser scans of the fossils formed the basis of the data. They made it possible to reconstruct the anatomy and thus provided information on aspects such as weight distribution, wingspan and muscle placement. The researchers then fed the data obtained into aerodynamic computer models in order to reconstruct how Yi qi and Ambopteryx might once have flown.
Grade poor to sufficient
Their results show that the animals could not take off from the ground, were not capable of active flight, and probably could not move their wings in a flapping manner very effectively. Presumably they could only slide from tree to tree. But the concept did not even seem to be ideally suited for this, as the aerodynamic analyzes showed. Presumably Yi qi and Ambopteryx also moved rather awkwardly through the air.
But why did these dinosaurs produce the unusual, but rather poor concept of wings? The researchers explain that the ability to glide probably brought them advantages. “If an animal has to travel long distances for whatever reason, gliding is a very fast method of locomotion,” says first author Alexander Dececchi from Mount Marty University in Yankton (USA). “It is also a very effective way to escape from enemies,” explains the scientist. But the wing concept of Yi qi and Ambopteryx was simply not competitive in the long run, he and his colleagues are convinced.
“Especially when the first versions of the birds rose into the air, these animals probably lost out,” says Dececchi. It is becoming apparent that with their comparatively inefficient concept they could only survive a few million years. When the better equipped “models” of evolution spread, they finally disappeared completely. The flight system of the Scansoriopterygidae was a dead end, sum up Dececchi and his colleagues. “We see a unique but failed design in this concept, which suggests that the conquest of the air in the mid to late Jurassic was dynamic and complex,” the scientists say.
Source: Cell Press, technical article: iScience, doi: 10.1016 / j.isci.2020.101574