The assembly of the avian body plan: a 160-million-year long process
The assembly of the avian body plan: a 160-million-year long process
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DOI：
10.4435/bspi.2018.01
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发表时间：
2018-01-01
影响因子：
1.1
通讯作者：
Cau, Andrea
中科院分区：
文献类型：
--
作者：
Cau, Andrea
鸟类是脊椎动物中最成功的类群之一。鸟类从爬行动物祖先的起源传统上植根于侏罗纪“Urvogel”始祖鸟附近，这种方法有助于界定“爬行动物”和“爬行动物”之间的二分法，（前始祖鸟）和“鸟类”（始祖鸟之后）相反，一个单一的进化连续体的各个阶段，来自化石记录的大量证据填补了灭绝之间的空白，恐龙、中生代鸟类和现代鸟类，并导致对鸟类生物学进化中始祖鸟之前和之后阶段之间误导性的二分法的修正。在此，使用系统发育方法的组合回顾了现代鸟类身体平面从原始祖先条件的逐步组装。导致现代鸟类的茎谱系使用38个节间进行描述，根据骨骼模块性，分支发生事件时间，发散率推断和形态空间占据第一阶段（“赫胥黎阶段”早三叠世至中侏罗世），鸟类的最早祖先获得了颅后发育，一种专性的两足和趾行姿势，三趾手和羽毛状珠被（“奥斯特罗姆阶”侏罗纪后半期）的特征是进化速度加快，hypercamival的丧失，脑腔的扩大，尾股模块的急剧减少，和真正的羽状羽毛的发展到动力飞行的过渡是在第三阶段才实现的（白垩纪“马希期”），由于前肢和尾部的重组成为适应飞行的器官，并完全获得了现代的鸟喙，将鸟类进化的研究局限于某些侏罗纪的paravians或始祖鸟的冠向谱系，忽略了超过60%的进化原因。形成第三阶段的大多数关键要素是在赫胥黎和奥斯特罗姆阶段的不同生态和功能制度下发生的新奇事物的解释，如果不参考它们最初的历史背景，就不能正确解释。
Birds are one of the most successful groups of vertebrates The origin of birds from their reptilian ancestors is traditionally rooted near the Jurassic "Urvogel" Archaeopteryx, an approach that has contributed in defining the dichotomy between the "reptilian" (pre-Archaeopteryx) and "avian"(post-Archaeopteryx) phases of what is instead a single evolutionary continuum A great and still ever increasing amount of evidence from the fossil record has filled the gaps between extinct dinosaurs, Mesozoic birds and modem avians, and led to the revision of the misleading dichotomy between pre- and post-Archaeopteryx stages in the evolution of bird biology Herein, the progressive assembly of the modem avian body plan from the archosarian ancestral condition is reviewed using a combination of phylogenetic methods The stem lineage leading to modem birds is described using 38 internodes, which identity a series of progressively less inclusive ancestors of modem birds and their Mesozoic sister taxa The 160-million-year long assembly of the avian bauplan is subdivided into three main stages on the basis of analyses of skeletal modularity, cladogenetic event timing, divergence rate inference and morphospace occupation During the first phase ("Huxleyian stage" Early Triassic to Middle Jurassic), the earliest ancestors of birds acquired postcranial pneumatisation, an obligate bipedal and digitigrade posture, the tridactyl hand and feather-like integument The second phase ("Ostromian stage" second half of Jurassic) is characterised by a higher evolutionary rate, the loss of hypercamivory, the enlargement of the braincase, the dramatic reduction of the caudofemoral module, and the development of true pennaceous feathers The transition to powered flight was achieved only in the third phase ("Marshian stage" Cretaceous), with the re-organisation of both forelimb and tail as flight-adapted organs and the full acquisition of the modem bauplan Restricting the investigation of the avian evolution to some Jurassic paravians or to the lineages crown-ward from Archaeopteryx ignores the evolutionary causes of over 60% of the features that define the avian body The majority of the key elements forming the third phase are exaptations of novelties that took place under the different ecological and functional regimes of the Huxleyian and Ostromian stages, and cannot be properly interpreted without making reference to their original historical context.