The first flying dinosaurs had no chance of lasting.

“They could not compete with birds of similar size because the latter was better flyers.”

Artist’s impression of Ambopteryx hovering – © Gabriel Ugueto

Possessing membranous wings, similar to those of bats, the first flying dinosaurs were so inefficient at this task that they were quickly supplanted by birds, according to this new study.


Birds evolved from dinosaurs, and it was long believed that they were the only branch of evolution to have acquired the ability to fly. But in 2015, researcher Xing Xu, of the Beijing Institute of Vertebrate Paleontology, announced the discovery by his team of a surprising fossil called Yi qi, literally meaning “strange wing” in Mandarin, with wings made of ‘a membrane resembling that of bats, rather than feathers. Four years later, the fossil of another species with membranous wings, called Ambopteryx longibrachium, was unveiled.

As part of work recently featured in the journal iScience, a team of researchers including Xu and Alex Dececchi of Mount Marty University in South Dakota conducted a more detailed analysis of these animals’ flight abilities. It was based in part on laser scans of the fossil discovered in 2015, which revealed unprecedented details regarding its soft tissues’ structure.

Researchers have made several hypotheses as to the exact configuration of the wings of the prehistoric animal. According to them, the latter could have proved to be close to that of bats (with wings connected directly to the animal’s legs), similar to that of modern birds, or even constitute a mixture of the two.

The results suggest that Yi and Ambopteryx were not only unable to propel themselves using their wings, as previously thought, but also turned out to be very bad gliders, probably less effective at this task than some modern animals such as flying squirrels. This suggests that they were arboreal creatures hovering only for short distances.

Map of the preserved skeleton and soft tissues of Yi – © Dececchi et al. 2020


When Yi and Ambopteryx evolved around 160 million years ago, there were no birds, and the sky was dominated by relatively massive pterosaurs (a distinct group of dinosaurs). According to the team, when the birds first appeared millions of years later, the membranous-winged dinosaurs were at an evolutionary stalemate.

“They couldn’t compete with birds of similar size because the latter was better flyers, nor could they grow massive to compete with pterosaurs,” explains Dececchi. “This type of dinosaur didn’t have the slightest chance of continuing. “

Although bats, which appeared around 50 million years ago, have developed into peerless acrobats, the study’s authors suggest that this scenario may have happened because they were nocturnal creatures (unlike Yi and Ambopteryx) therefore not in direct competition with birds.

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