Evolution of key biological characteristics in dinosaurs and their relatives

恐龙和它们的近亲，包括翼龙和鳄鱼，组成了爬行类始祖目。在中生代的大部分时间里，祖龙主导着大型陆生脊椎动物的生态位，而被称为鸟类的改良恐龙约占现存物种的1万种。祖龙的生物学特征一定有助于解释它们的成功，但祖龙生物学的许多方面只能在现存的鸟类和鳄鱼身上直接研究。对于已灭绝的始祖龙，它们必须通过化石证据、与现存动物的比较以及生物力学建模等方法来推断。******我的实验室将研究始祖龙及其近亲的关键功能的进化，特别是通风和陆地运动。通气，即空气进出身体的过程，在始祖身上很有趣，因为鸟类和鳄鱼都有一个单向肺（即只允许气流向一个方向）。此外，这两种动物的肋骨都有被称为钩状突的翼缘，用来固定通气肌，但鳄鱼的钩状突在解剖学上与鸟类不同。需要对各种已灭绝的祖龙的通气系统进行研究，以确定鸟类和鳄鱼在这一领域的相似性是反映了共同的原始祖龙特征，还是仅仅是趋同的进化。******同样，已灭绝的祖龙在陆地上的运动也提出了许多重要的问题。在始祖龙的早期历史中，发生了从爬行的、类似蜥蜴的后肢姿势到直立姿势的转变，但这种转变的细节尚不清楚，而在同一进化间隔内，前肢姿势的进化几乎没有被探索过。恐龙在陆地上的运动得到了更好的研究，但一些主要问题仍未解决，包括为什么鸟臀目恐龙和一些兽脚亚目恐龙的耻骨轴会独立地“向后”（即向后旋转）。******我的实验室将通过将肌肉骨骼数字建模技术应用于选定的化石标本来解决祖龙通风和陆地运动的主要问题。后肢和前肢的模型将用于量化参数，如肌肉力矩臂，使测试关于姿势和运动的假设成为可能。躯干骨骼的模型将揭示各种始祖龙的通气运动，以及钩突和其他附属结构的作用。将这些功能研究的结果放在祖龙系统发育的背景下，将有助于推断祖龙运动和通风的进化，有助于识别可能有助于祖龙生态成功的功能创新。

Dinosaurs and their close relatives, including pterosaurs and crocodilians, comprise the reptilian group Archosauria. Archosaurs dominated large terrestrial vertebrate niches throughout most of the Mesozoic, and the modified dinosaurs known as birds account for about 10,000 living species. The biological characteristics of archosaurs must help to explain their success, but many aspects of archosaurian biology can be studied directly only in living birds and crocodilians. For extinct archosaurs, they must be inferred using fossil evidence, comparisons to living animals, and approaches such as biomechanical modelling.******My lab will investigate the evolution of key functional capabilities, particularly ventilation and terrestrial locomotion, in archosaurs and their close relatives. Ventilation, the process of moving air into and out of the body, is intriguing in archosaurs because both birds and crocodilians have a unidirectional lung (i.e. one allowing airflow in only one direction). Furthermore, the ribs of both groups bear flanges called uncinate processes that anchor ventilatory muscles, but the poorly known uncinate processes of crocodilians differ anatomically from those of birds. Studies of the ventilatory system in various extinct archosaurs are needed to determine whether the similarities in this domain between birds and crocodilians reflect shared, primitive archosaurian features or merely convergent evolution.******Similarly, terrestrial locomotion in extinct archosaurs presents many important problems. A shift from a sprawling, lizard-like hindlimb posture to an upright one occurred in the early history of Archosauria, but the details of this transition are uncertain, and the evolution of forelimb posture during the same evolutionary interval is nearly unexplored. Terrestrial locomotion in dinosaurs is better studied, but some major questions remain unresolved, including why the shaft of the pubis became independently “retroverted” (i.e. rotated posteriorly) in ornithischian dinosaurs and some theropods.******My lab will address major issues of archosaur ventilation and terrestrial locomotion by applying musculoskeletal digital modelling techniques to selected fossil specimens. Models of the hindlimbs and forelimbs will be used to quantify parameters such as muscle moment arms, making it possible to test hypotheses about posture and locomotion. Models of the trunk skeleton will shed light on ventilatory movements in various archosaurs, and the role of uncinate processes and other accessory structures. Placing the results of these functional studies in the context of archosaur phylogeny will permit inferences about the evolution of locomotion and ventilation within Archosauria, facilitating identification of functional innovations that may have contributed to archosaurian ecological success.