Flight and flight control in short-tailed Pterosaurs

翼龙是一群会飞的中生代始祖龙，代表着第一批实现真正动力飞行的脊椎动物。虽然它们在晚三叠世的出现和在马斯特里提斯(晚白垩世)灭绝之间的整体外观变化不大，但飞行装置的大小和结构的变化将对它们的生态和空气动力学性能产生明显的影响。就大小而言，最小的翼龙、食蚁龙和最大的脊椎动物之间的差异很大，例如Quetzcoatlus northropi(Lawson 1975)，Hatzegopterxyx(Buffetaut et al 2002,2003)。虽然一些物种的翼展只有约250毫米，但像隐翅龙(Wang Et Al 2008)这样的物种的翼展却至少长到了10米，这使它可以与几种现代人造飞机相媲美，而残缺不全的遗骸表明，其他物种(如Hatzegopteryx)可能会变得更大。除了大小之外，在衍生的翼趾类中至少有3种不同的肩带结构被证明，这与基础翼龙的情况不同(Frey等人。2003a)。翼龙的肢体结构及其相关的膜构成了主要和支撑的飞行表面，关于这些动物在如此不同的大小和不同的环境条件下必须面对的空气动力学和气动弹性挑战，尚未得到充分的研究。本项目旨在调查基础翼龙和衍生翼龙的空气动力学性能，因此提供了一项不同于以往尝试的研究，通过考虑代表广泛尺寸和飞行形态的分类群。通过检查关键标本和应用新的分析技术(例如，物理/计算机模拟、有限元分析)，这项工作将扩展到翼龙飞行力学的创新研究。我们期待着随之而来的对短尾翼龙起源和进化的洞察，并回答为什么这个群体可以进化出如此广泛的飞行设备？它还探讨了这种变化如何与白垩纪末期摄食习惯的多样化和巨人症的增加相结合。最后，它的目的是研究观察到的从基生的长尾、短颈类群到小尾、长颈翼手指目的变化，并证明这种形态上的根本变化的空气动力学意义。然后，空气动力学的影响可以被认为是更广泛理论的一部分，即是什么驱动了翼指目和非翼指类翼龙之间的进化机制。

The pterosaurs, a group of flying Mesozoic archosauromorphs, represent the first vertebrates to have achieved true, powered flight. While their overall appearance changed little between their appearance in the late Triassic and their extinction in the Maastrictian (Late Cretaceous), alterations in both size and configuration of the flight apparatus would have had a clear impact on their ecology and aerodynamic performance.In terms of size the range between the smallest pterosaurs, the anurognathoids, and the largest azhdarchids, e.g. Quetzalcoatlus northropi (LAWSON 1975), Hatzegopterxyx (BUFFETAUT et al 2002, 2003), is substantial. While species such as Nemicolopterus crypticus (WANG et al 2008) had a wingspan of only ~250mm Q. northropi grew to at least 10m in span, making it comparable to several modern man-made aircraft, while fragmentary remains suggest that other species (e.g. Hatzegopteryx) could grow larger still. In addition to size at least 3 separate shoulder girdle configurations have been demonstrated in the derived pterodactyloids, differing from that of the basal pterosaurian condition (FREY et al. 2003a). The evolution of the limb configurations, and their associated membranes, that formed the main and supporting flight surfaces, has yet to be fully investigated with regards to the aerodynamic and aeroelastic challenges that these animals must have faced operating at such vastly different sizes and in a variety of environmental conditions.This project seeks to investigate the aerodynamic performance of basal and derived pterosaurs and thus provides a study that differs from previous attempts by considering taxa which represent both a wide range of size and flight configurations. Through an examination of key specimens and the application of new analytical techniques (e.g. Physical/computer modelling, FEA) this work will be extended into innovating research on pterosaur flight mechanics. We expect accompanying insights into the origins and evolution of short-tailed pterosaurs and an answer to the question, why this group could evolve such a wide range of flight apparatuses? It also seeks how such alterations can be coupled with the diversification of feeding habits and increasing gigantism towards the end of the Cretaceous Period. Finally it aims to investigate the observed change from basal long tailed, short necked taxa to the small tail, long necked pterodactyloids and document the aerodynamic significance of this fundamental change in morphology. Aerodynamic influences can then be considered as part of a wider theory on what drove the evolutionary mechanisms between pterodactyloid and non-pterodactyloid pterosaurs.