The winged giants of yesteryear cannot soar dynamically – News Home

唉,化石动物的行为并没有石化

How did ancient winged animals fly with wingspans two or three times that of the largest modern birds? There is no definite answer to this question. A team of scientists from Japan and France used aerodynamic models to assess the soaring flight characteristics of the extinct giants, the ancient birds Argentavis and Pelagornis, and the pterosaurs Pteranodon and Quetzalcoatl. Comparing these estimates with estimates for modern birds, the researchers concluded that ancient birds with a wingspan of 6 to 7 meters and pterosaurs of roughly the same size likely used updrafts to soar through the air (a so-called static Soaring), but the giant pterosaurs with a wingspan of twelve meters have had problems with soaring flight.

Throughout our planet’s history, the ability to actively fly has developed repeatedly in a variety of animals, from tiny to truly enormous. Thus, the smallest flying animal in Earth’s history is thought to be a modern-day miniature wasp rider. water chestnut. The females of these ichneumons are only 550 microns long, not much Ciliate Shoes, wingless and blind males are about three times smaller.As for the record holder on the opposite side of the scale, the “throne” there is undoubtedly occupied by giants pterosaurs: their wingspan reaches 11-12 meters (for example, in pterosaur), which is comparable to the size of a light aircraft How to – 12.


“扑翼机”起飞

If there are no questions about the possibility of flying with modern detritus, extinct giants, of which only petrified bones have been preserved for a century, have forced scientists to try to explain how these gigantic creatures were not only able to take off, but also stay in Air (EH Hankin, DMS Watson, 1914. About the flight of pterodactyls). The results of the first biomechanical study using a full-scale animal model indicated that an 80 kg pterosaur likely remained in the air, hovering in the air currents (P. MacCready, 1984. great pterosaur project). However, weight estimates for giant pterosaurs have now risen substantially, and it is believed that, for example, Quetzal Cottle (feathered snake god) should weigh at least 200 kg with a wingspan of 12 m (DM Henderson, 2010. Pterosaur weight estimates from 3D mathematical slices)。

After that, opinions were divided: while some scientists believed that Quetzalcoatl and similar giant pterosaurs were flightless terrestrial predators, others believed they had excellent flight abilities and the ability to stay in the air for days, Flying distances up to 19,000 km (MP Witton, MB Habib, 2010. Comments on the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues, and the lack of flight in pterosaurs). Of course, the latter possibility must be related to the soaring ability of Feathered Serpents, who, like the largest modern birds, spend most of their time flying using wind energy or rising heat flux (K. Sato et al., 2009. The soaring scale of seabirds and its impact on the flying ability of giant pterosaurs). But can this giant, like other extinct giants, soar in the air?

To answer this question, we first have to remember that modern birds have two main ways soar: dynamic and static. In dynamic soar, a bird uses the difference in wind speed at different altitudes to move between layers of air to maintain its own flight speed: that’s how many seabirds fly with long, narrow wings, such as albatrosses. First, they glide downwind, accelerate, and near the water, where the wind speed decreases due to the friction of the water, they turn against the wind and rise again, where the air moves faster.

Static surges are due to rising airflow: these can be thermal, warm air currents, or simply rising air masses that appear over various ground obstacles such as mountains or forests. Circling up to great heights with the help of a rising stream, the bird then begins to slide down slowly, using its long, wide wings, such as can be seen on eagles (see news Ospreys use ascent when flying over the sea) Airflow, “Elements”, 19 Jan 2019).

Each type of soaring has its own requirements for the area and length of the wings and their loads. So, after knowing the corresponding indicators of modern flying birds, the scientists decided to find out whether extinct species were able to move in this way. Four-winged ancient giants became “guinea pigs” – two birds and two pterosaurs: Argentine (silver; Miocene birds with a wingspan of about 7 m), Geranium (Geranium; Oligocene birds with a wingspan of about 7 m), pterosaurs (Pteranodon; wingspan about 6 meters) and Quetzal Cottle (Wingspan about 9 meters).

For comparison, several modern birds with different soaring abilities were selected: for example, Wandering Albatross (Diomedes in exile; wingspan about 3 meters) is an “expert” in dynamic soaring, California Condor (Gymnogyps californianus; wingspan 2.75 m) and gorgeous frigate (gorgeous frigate; 2.3m wingspan) prefers static soaring, while African bustard (aldiotis choir; wingspan 2.5m) with little hovering capability. I note that all the figures given are from the article in question,​​in fact, the wingspan of the Feathered Serpent may be a bit larger (MP Witton, MB Habib, 2010. Comments on the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues, and the lack of flight in pterosaurs)。

非洲大鸨是现代最重的飞鸟。

To understand what type of soaring the extinct animals might have used, scientists calculated various metrics of their flight, such as the minimum wind speed required for sustained soaring and the glide ratio, the ratio of the distance the animal traveled to the altitude it failed to overcome in order to overcome it. Some data obtained by previous researchers was taken into account, but can be adjusted for more modern flight style data (eg, pterosaurs were found to be most efficient at low speeds, their wing membranes could not withstand high-speed flight; C. Palmer , 2010. Slow motion flight: the aerodynamics of a pterodactyl wingC. Palmer, 2017. Inferring properties of pterosaur wing membranes) and the size of extinct animals. Since there is still disagreement about the mass of giant pterosaurs, the authors used several estimates from different works.

Using equations of motion to calculate the dynamics of soaring animals, the calculation process for dynamic soaring and thermal soaring is different. The scientists used physical models and numerical optimization methods to quantify the soaring dynamics and required wind speeds. This method, developed in the engineering field, provides a basis for quantifying the soaring dynamics and required wind conditions of gliders and birds. However, despite its effectiveness, the only animal to which this method has been applied so far has been the wandering albatross: it has never been applied to the extinct giant flying object.

根据作者的结论,已经灭绝的巨型鸟类和无齿翼龙只能进行热腾腾。

Dynamic soaring was especially “unlucky”: the researchers’ calculations showed that Argentavis, Pteranodon and Quetzalcoatl were absolutely incapable of such flight due to the extremely high wind speeds required and lower dynamic soaring characteristics than all modern birds. For Pelagornis, the final verdict was largely determined by an assessment of body weight: at the largest possible (40kg), the giant bird also proved to be “beyond” the characteristics required for efficient soaring, but even with body weight At only 22kg, Pelagornis is still a poor soarer, not as good as an albatross in this regard. Although the long, narrow wings of Pelagornis were previously thought to be ideal for this type of soaring (DT Ksepka, 2014. Maximum bird flight performance), the new model suggests that Pelagornis’ wings are too long for efficient dynamic flight.

In terms of heat, all extinct species exhibited high soaring performance, with glide ratios comparable to those of modern species. As for the soaring phase, the ascent phase of circling flight along the updraft, then according to the authors’ calculations, the characteristics of Pelagornis, Argentavis and Pteranodon are not only comparable, but sometimes even better than their characteristics. bird today. In the case of Pterosaurs, the data would vary based on the animal’s estimated mass, but would be consistent with modern-day flying birds anyway. But another pterosaur, Feathered Serpent God, can’t say the same: its soaring ability is extremely low, not even as good as the performance of the African Great Bustard, it rarely flies, never soars.

羽蛇神可能走了很多路

Therefore, the modeling performed by the authors confirmed previous data on the Argentavis flight method (S. Chatterjee et al., 2007. Aerodynamics of Argentavis, the world’s largest flying bird in the Miocene, Argentina), specified the flight method of Pterodactyl (previously assumed it was capable of soaring dynamically and statically) and completely changed the idea of ​​Pelagornis and Quetzalcoatl flying, one of which resulted in “retraining” into the thermal soar, the second Generally “culled from the category of animals capable of soaring”. Previously, it was thought that Quetzalcoatl’s movement in the air was primarily due to hovering, as it was unable to flap its wings for long periods of time (MP Witton, MB Habib, 2010. Comments on the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues, and the lack of flight in pterosaurs). Now, considering that its hovering ability was probably even worse than that of a modern bustard, we can only assume that this huge pterosaur was only briefly in the air, making short but powerful flights during which it had to constantly work its wing.

Considering Quetzalcoatl’s adaptation to walking (MP Witton, D. Naish, 2008. Reassessment of functional morphology and paleoecology of azhdarchid pterosaur), lack of adaptability to prolonged flapping flight, and the phylogenetic trend of pterosaurs—dragon Flight efficiency has declined (pterosaur flight has steadily improved over the course of evolution, Elements, 2 Nov 2020), and it can be assumed that these giants lived a different way of life than eagles and vultures, but, say, Cape Kaffir Crow (cormorant) and spend most of their time on the ground, where they hunt for food and communicate with relatives. Perhaps, had it not been for the mass extinction 66 million years ago, the further evolution of Azdaki animals would have led to the emergence of a completely flightless animal reminiscent of our ostrich.

Of course, the data obtained (which the study authors acknowledge) cannot be considered absolute: the flight characteristics of flying creatures depend to a large extent not only on the size and mass of the animals, but also on the paleoecological characteristics of the animals. In the regions they inhabited (eg, flying in a canyon would fly significantly over the plains), our understanding of the flight mechanics of ancient animals depends heavily on the model chosen and the completeness of knowledge of their anatomical features.

resource: Y. Goto, K. Yoda, H. Weimerskirch, K. Sato. How did extinct giant birds and pterosaurs fly?A Comprehensive Modeling Approach to Evaluate Soaring Performance // PNAS link. 2022. DOI: 10.1093/pnasnexus/pgac023.

Anna Novikovskaya



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