Giant pterosaur Quetzalcoatl turned out to be a bad flyer

(ORDO NEWS) — Japanese and French scientists have created aerodynamic models and applied them to the large flying vertebrates of the past. It turned out that the giant pterosaur Quetzalcoatl was not capable of long-term flight: it could take to the air only as a last resort.

The models also confirmed that the Argentavis used thermal updrafts for hovering, much like its modern relatives, the condors.

In addition, the ancient bird Pelagornis (previously it was believed that it is characterized by dynamic soaring, like albatrosses) and Pteranodon turned out to be adapted to this type of soaring. The study is published in the journal PNAS Nexus.

For large birds, flapping flight is too energy-consuming, so they prefer to soar. Soaring flight is of two types: static and dynamic. During static soaring, birds use ascending currents of warm air (thermals), but sometimes they can also use currents that flow around obstacles, such as mountain slopes or hills.

This type of soaring is typical both for various land birds (eagles, vultures, storks) and for some sea birds (frigates and pelicans) – the latter can also use streams flowing around the waves.

Other seabirds, such as albatrosses or petrels, are characterized by dynamic soaring, in which the birds use the difference in wind speeds above the water surface and at altitude. These birds can also use flow streams.

Scientists of various specialties have long been interested in the question of what type of soaring was characteristic of the flying giants of the past. Among the largest flying vertebrates is Sanders’ Pelagornis (Pelagornis sandersi), which lived 28-25 million years ago, a distant relative of geese and chickens.

It may have had the largest wingspan of any bird, with an upper estimate of 7.38 meters. Slightly inferior to the pelagornis Argentavis (Argentavis magnificens), who lived about six million years ago: its wingspan reached seven meters.

Some pterosaurs were much larger than these birds. The wingspan of the quetzalcoatlus (Quetzalcoatlus northropi) and its closest relatives could reach 10-11 meters in length, making them the largest flying animals in the history of the planet.

However, a large number of studies have been devoted to the smaller and probably the most famous pterosaur, Pteranodon (Pteranodon spp.), whose wingspan was comparable to that of Pelagornis and Argentavis.

Giant pterosaur Quetzalcoatl turned out to be a bad flyer 2
Artist’s reconstruction of Quetzalcoatls during a hunt

Studies have shown that Argentavis used thermals, like its condor relatives, and Pelagornis, like the albatrosses it resembled, was characterized by dynamic flight.

The type of soaring of Pteranodon and Quetzalcoatl was first identified as dynamic and static, respectively, but then it was shown that the wings of pterosaurs were not adapted to dynamic soaring.

Yusuke Goto of the National Center for Scientific Research of France and his Japanese and French colleagues decided to analyze the flight of these four taxa, since in previous work the flight performance and wind speed had not been comprehensively assessed.

Scientists estimated these indicators using aerodynamic models, and then compared the results with data from modern birds.

The first model showed that Argentavis, Quetzalcoatl, and Pteranodon were indeed not capable of dynamic soaring, while Pelagornis turned out to be much less adapted to it than albatrosses.

The second model confirmed that Argentavis used updrafts for hovering. However, it turned out that Pelagornis was also perfectly adapted to static soaring. Pteranodon performed well at a low body weight estimate (18.6 kilograms), but at a high one (36.7 kilograms) it was inferior to modern and extinct birds.

Quetzalcoatl turned out to be poorly adapted to static flight: for normal soaring, he needed a very high speed of the upward flow of air. Its performance was even worse than that of the African great bustard (Ardeotis kori), which only flies when threatened.

This is due to the high specific load on the wing – the ratio of the mass of the animal to the wing area. The authors note that in previous studies, due to the application of the principal component method, the wing loading in Quetzalcoatl was underestimated.

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Comparison of sizes and types of soaring in extinct and modern flying vertebrates. Thermal soarer – adapted to static hovering (using thermals), dynamic soarer – to dynamic hovering, poor soarer – poorly adapted to hovering

Scientists conclude that both Pteranodon and Pelagornis hovered over the oceans using updrafts of air, as frigatebirds do today.

Quetzalcoatl data refute claims that large azhdarchids were capable of long flights of several thousand kilometers. Considering that azhdarchids most likely hunted on the ground, they took to the air only when absolutely necessary.

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