PRF: A Developmental, Functional and Paleontological Study of Avian Tail Evolution

尾巴是鸟类飞行起源的中心。然而，尽管翅膀受到了广泛的关注，但鸟类的尾巴并不是发育、功能或古生物学研究的重点。与始祖鸟和其他兽脚类动物的祖先相比，现代飞鸟的尾巴非常短。减尾是尾椎减少和远端节段融合成一种独特的鸟类结构的产物，这种结构是形成尾羽的基础。在这个研究项目中，PI将结合几个学科的方法来研究鸟类尾部形态的进化。(I)将利用鹌鹑-雏鸡嵌合体技术描述正常的尾巴个体发育，并用于实验以阐明节段数调节和烟柱形成的机制。(Ii)在对鸽子在八种运动模式下的功能研究中，将量化尾巴的运动控制和运动学。(3)将根据第(I)和(Ii)项中获得的新资料重新评估有关的鸟类化石。这些研究的结果将对每个单独的领域具有重要意义。然而，来自这三个学科的信息在系统发育框架内的史无前例的整合将为评估发育、功能和系统发育的影响如何促进或限制形式的进化提供一个更全球化的视角。

The tail is central to the origin of avian flight. However, despite extensive attention to the wing, the tail of birds has not been the focus of developmental, functional or paleontological studies. Modern flying birds possess a very short tail compared to Archaeopteryx and other theropod ancestors. Tail reduction is the product of fewer caudal vertebrae and the fusion of distal segments into a uniquely avian structure, the pygostyle, which forms a base for the tail feathers. In this research project, the PI will combine approaches from several disciplines to study the evolution of this caudal morphology in birds. (I) The quail-chick chimera technique will be employed for a description of normal tail ontogeny and for experiments to elucidate mechanisms of segment number regulation and pygostyle formation. (II) The motor control and kinematics of the tail will be quantified in a functional study of the pigeon during eight locomotor modes. (III) Pertinent fossil birds will be reevaluated in light of the new information obtained in (I) and (II). Results from these studies will have significance for each individual field. However, the unprecedented integration of information from these three disciplines within a phylogenetic framework will provide a more global perspective for evaluating how developmental, functional and phylogenetic influences facilitate or constrain the evolution of form.