The largest extinct volant birds (Pelagornis sandersi and Argentavis magnificens) and pterosaurs (Pteranodon and Quetzalcoatlus) are thought to have used wind-dependent soaring flight, similar to modern large birds. There are two types of soaring: thermal soaring, used by condors and frigatebirds, which involves the use of updrafts to ascend and then glide horizontally over the land or the sea; and dynamic soaring, used by albatrosses, which involves the use of wind speed differences with height above the sea surface. Previous studies have suggested that Pelagornis sandersi used dynamic soaring, while Argenthavis magnificens, Pteranodon, and Quetzalcoatlus used thermal soaring. However, the performance and wind speed requirements of dynamic and thermal soaring for these species have not yet been quantified comprehensively. We quantified these values using aerodynamic models and compared them with that of extant birds. For dynamic soaring, we quantified maximum flight speeds and maximum upwind flight speeds. For thermal soaring, we quantified the animal’s sinking speed circling at a given radius and how far it could glide losing a given height. Our results confirmed those from previous studies that Pteranodon and Argentavis magnificens used thermal soaring. Conversely, the results for Pelagornis sandersi and Quetzalcoatlus were contrary to those from previous studies. Pelagornis sandersi used thermal soaring, and Quetzalcoatlus had a poor ability both in dynamic and thermal soaring. Our results demonstrate the need for comprehensive assessments of performance and required wind conditions when estimating soaring styles of extinct flying species.

中文翻译：

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已灭绝的巨型鸟类和翼龙的翱翔风格

已灭绝的最大的飞翔鸟类（Pelagornis sandersi和Argentavis magnificens）和翼龙（Pteranodon和Quetzalcoatlus）被认为使用了依赖风的翱翔飞行，类似于现代大型鸟类。有两种类型的翱翔：热腾腾，由秃鹰和军舰鸟使用，涉及使用上升气流上升，然后在陆地或海洋上水平滑翔；和动态翱翔，由信天翁使用，涉及使用风速与海面以上高度的差异。以前的研究表明，Pelagornis sandersi使用动态翱翔，而Argenthavis magnificens、Pteranodon和Quetzalcoatlus用热腾腾。然而，这些物种的动力和热飙升的性能和风速要求尚未全面量化。我们使用空气动力学模型量化了这些值，并将它们与现存鸟类的值进行了比较。对于动态翱翔，我们量化了最大飞行速度和最大逆风飞行速度。对于热腾腾，我们量化了动物在给定半径内盘旋的下沉速度，以及它在失去给定高度的情况下可以滑翔多远。我们的结果证实了先前研究中的那些，即Pteranodon和Argentavis magnificens使用热飙升。相反，Pelagornis sandersi和Quetzalcoatlus的结果与先前研究的结果相反。Pelagornis sandersi使用热腾飞，而Quetzalcoatlus的动力和热腾腾能力都很差。我们的结果表明，在估计已灭绝飞行物种的翱翔方式时，需要对性能和所需的风力条件进行综合评估。