Modernization, diversification, and domination: Macroevolutionary origins of living bird diversity

现代鸟类包括10,000多种活着的物种，占据了令人眼花缭乱的生态位空间，几乎栖息在现代世界的每一个角落。为了研究这种壮观的多样性的起源，以及生物学上现代鸟类形成的逐步顺序，从中生代羽毛恐龙化石记录中获得的见解至关重要，记录现代鸟类崛起的早期新生代化石也是如此。在这里，我概述了一项雄心勃勃的研究计划，该计划由不同但大致重叠的研究路线组成，旨在阐明鸟类的早期进化史。这项工作将使我们比以往任何时候都更接近于更全面地了解地球上最具优势的生物群体之一的起源。拟议的计划建立在我在鸟类进化生物学多个领域的高调研究基础上，并将提供对鸟类宏观进化中一些最重要和历史最悠久的问题的基本见解。工作将被分成几个项目，旨在澄清现存鸟类的壮观多样性、它们的特殊特征以及它们异常的表型差异是如何、在哪里和何时出现的。这些研究将利用来自关键的未描述化石的丰富的新的三维数据、尖端的可视化技术，以及来自正在进行的国际合作的大量新的表型和基因组数据。i)如何：追踪现代鸟类头骨的起源，以及复杂的鸟类飞行。在恐龙时代现代鸟类的近亲中，三维保存下来的化石极其罕见。这一时期的精美新化石独一无二地展示了三维保存下来的头骨和骨骼。高分辨率CT扫描结合三维数学分析将阐明现代鸟类大脑的起源，尖端的运动范围分析将阐明现代鸟类飞行中风是如何演变的。ii)在哪里：现代鸟类地理模式的起源，以及历史气候波动在构建鸟类分布结构中的作用。我们之前已经证明，许多现代鸟类的地理分布在它们的进化史上有很大的波动，但这些洲际范围转移的原因尚不清楚。通过将最新的古气候模型与尖端的“生态位模型”方法相结合，我们将首次测试过去6600万年的气候变化对这些模式的影响程度，并预测未来气候驱动的地理变化。通过采取三管齐下的方法(开发新的发散时间模型，从未被研究的物种中生成新的序列数据，以及评估新的化石校准)，我们准备生成第一张全面且准确的现代鸟类生命树的时间尺度图，这是朝着识别产生地球现代鸟类生物多样性的模式和过程迈出的基本一步。这也将阐明地球历史上的重大事件，如导致巨型恐龙死亡的大规模灭绝事件，是如何塑造鸟类进化的。这个跨学科项目将对教学、博物馆展览、数字藏品建设和媒体产生影响，并将涉及许多早期职业科学家。该项目的新数据(例如，关键现代鸟类和新化石的CT扫描)将提供数字遗产，供所有人免费使用。这些数据将有助于未来对鸟类进化的无数研究，并结合出版物附带的媒体曝光，将教育年轻人和老年人关于进化和古生物学的知识。为此，该项目的可视数据将被纳入塞奇威克地球科学博物馆的展览中，允许公众操纵数字和物理标本。

Modern birds comprise over 10,000 living species, occupying a dizzying range of niche space and inhabiting virtually every corner of the modern world. In order to study the origins of this spectacular diversity, as well as the stepwise sequence by which biologically modern birds came to be, insights from the Mesozoic fossil record of feathered dinosaurs are critical, as are early Cenozoic fossils documenting the rise of modern birds. Here, I outline an ambitious research programme composed of distinct, yet broadly overlapping lines of inquiry aimed at illuminating the early evolutionary history of birds. This work will bring us closer than ever before to a more complete understanding of the origins of one of Earth's most dominant living groups of organisms. The proposed programme builds on my high-profile research in multiple areas of avian evolutionary biology and will deliver fundamental insights into some of the most important and longest-standing questions in avian macroevolution. Work will be divided into projects aimed at clarifying How, Where, and When the spectacular diversity of living birds, their specialised features, and their extraordinary phenotypic disparity have arisen. These studies will draw on abundant new three-dimensional data from pivotally important undescribed fossils, cutting edge visualisation techniques, and a wealth of novel phenotypic and genomic data from ongoing international collaborations.i) How: Tracing the origin of the modern avian skull, and sophisticated avian flight. Three dimensionally preserved fossils are extremely rare among the closest relatives of modern birds from the Age of Dinosaurs. Exquisite new fossils from this interval, uniquely, exhibit both three-dimensionally preserved skulls and skeletons. High-resolution CT scanning combined with three-dimensional mathematical analyses will elucidate the origin of the modern avian brain, and cutting-edge range-of-motion analyses will illuminate how the modern avian flight stroke evolved.ii) Where: The origin of modern avian geographic patterns, and the role of historical climate fluctuations in structuring avian distributions. We have previously shown that the geographic distributions of many groups of modern birds have fluctuated dramatically through their evolutionary history, but the causes of these inter-continental range shifts are unclear. By combining the latest palaeoclimate models with cutting-edge 'niche modelling' approaches, we will test-for the first time-the extent to which climatic change over the last 66 million years may have contributed to these patterns and predict future climate-driven geographic changes.iii) When: Refining the timing of the modern avian radiation. By taking a three-pronged approach (developing new divergence time models, generating new sequence data from understudied species, and evaluating new fossil calibrations) we are poised to generate the first comprehensive and accurately time-scaled picture of the modern bird tree of life, a fundamental step toward discerning the patterns and processes that have generated Earth's modern bird biodiversity. This will also shed light on how major events in Earth history, like the mass extinction event that killed the giant dinosaurs, have shaped avian evolution. This interdisciplinary project will have impacts on teaching, museum exhibition, digital collections building, and media, and will involve many early career scientists. New data from this project (e.g. CT scans of key modern birds and new fossils) will provide a digital legacy to be made freely available to all. These data will facilitate myriad future studies on avian evolution, and combined with media exposure accompanying publications, will educate both young and old about evolution and palaeontology. To this end, visual data from this project will be incorporated into an exhibit at the Sedgwick Museum of Earth Sciences, allowing the public to manipulate both digital and physical specimens.