Reconstructing skull evolution of fossil crown birds

重建化石冠鸟的头骨进化

• 批准号: 2450377
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2450377
• 关键词: Reconstructing; skull; evolution; fossil; crown

What processes shape vertebrate diversity over large time scales? Previous approaches to this question have focused on many different factors, from life history, ecology, and biogeography to large-scale environmental change and extinction, and can use many different metrics to quantify diversity. To date, the majority of studies on the evolution of vertebrate diversity have focused on relatively simple metrics, specifically taxon counts or univariate measures, such as body size. However, an approach based on either of those measures would be unable to distinguish between an elephant and a whale, similarly-sized mammals that otherwise differ in most attributes of consequence for understanding and reconstructing organismal evolution. Multivariate morphological data requires more extensive time and effort to collect but ultimately provides a more complete picture of evolutionary and palaeoecological change. Moreover, morphological traits provide a bridge between studies of palaeoecological and palaeobiological change and studies of the genetic and developmental factors that intrinsically shape organismal morphology, and must also influence large-scale patterns of evolutionary change. Thus, a complete understanding of the patterns and processes underlying evolution requires an approach that can fully represent an organism's phenome, the sum total of their observable traits. Fortunately, recent advances in imaging and morphometric data analysis now allow for study of phenomic evolution across large clades. Huge improvements in data collection and data analysis in recent years have produced a step change in accuracy of evolutionary rates and identification of factors shaping diversity, in particular through quantifying the complex morphology of organisms. In my lab, we use high-density 3D surface morphometrics from surface and CT scans to reconstruct the evolution of organismal shape through development and across deep time, bridging datasets from embryos to fossils. Many studies have demonstrated that fossil data significantly improve the accuracy of evolutionary reconstructions; however, several hyperdiverse modern clades, such as birds, lack fossils that are well-preserved in 3-D, hindering their inclusion in these analyses. In this study, the student will use cutting-edge retrodeformation techniques to reconstruct the cranial morphology from micro-CT scans of early crown fossil birds housed in international collections, conduct high-density 3D morphometric analyses of those fossils, and combine them with existing data from Prof. Goswami's lab for over 400 extant birds to reconstruct the early evolution of birds and identify the ecological and environmental factors that shaped this highly successful radiation. Using our recent analyses identifying seven cranial modules in birds, s/he will test several hypotheses relating to ecological and developmental drivers of morphological diversity in living and extinct birds, analysing tempo and mode of evolution, and ecomorphology. The reconstructions of early birds alone will be of immense value to the broader community, but the project will ultimately provide a much more accurate understanding of the evolution of birds and what drove their immense diversification.

在大的时间尺度上，什么过程塑造了脊椎动物的多样性？以前对这个问题的研究集中在许多不同的因素上，从生活史、生态学和地理学到大规模的环境变化和灭绝，并且可以使用许多不同的指标来量化多样性。到目前为止，大多数关于脊椎动物多样性进化的研究都集中在相对简单的指标上，特别是分类单元计数或单变量测量，如体型。然而，基于这两种方法中的任何一种的方法都无法区分大象和鲸鱼，这两种大小相似的哺乳动物在理解和重建生物进化的大多数属性上都有所不同。多变量的形态数据需要更广泛的时间和精力来收集，但最终提供了一个更完整的进化和古生态变化的图片。此外，形态特征提供了古生态学和古生物学变化的研究和遗传和发育因素的研究之间的桥梁，这些因素在本质上塑造了生物体形态，也必须影响大规模的进化变化模式。因此，要完全理解进化背后的模式和过程，需要一种能够完全代表生物体表型组的方法，即它们可观察到的特征的总和。幸运的是，最近在成像和形态数据分析方面的进展现在允许跨大型分支研究表型进化。 近年来，数据收集和数据分析方面的巨大进步，特别是通过量化生物体的复杂形态，使进化速率的准确性和塑造多样性的因素的识别发生了重大变化。在我的实验室里，我们使用来自表面和CT扫描的高密度3D表面形态测量学来重建生物体形状在发育过程中的演变，并跨越时间，将数据集从胚胎连接到化石。许多研究表明，化石数据显着提高进化重建的准确性;然而，一些超多样性的现代分支，如鸟类，缺乏保存良好的3D化石，阻碍了它们在这些分析中的纳入。在这项研究中，学生将使用尖端的逆向变形技术，从国际收藏的早期冠鸟化石的微CT扫描中重建颅骨形态，对这些化石进行高密度3D形态测量分析，并将它们与Goswami教授实验室现有的400多种现存鸟类的数据相结合，以重建鸟类的早期进化，并确定生态和环境因素。形成了这种非常成功的辐射。利用我们最近的分析，确定鸟类的七个颅骨模块，s/他将测试几个假设有关的生态和发展的驱动因素的形态多样性在生活和灭绝的鸟类，分析克里思和模式的演变，和生态形态学。仅早期鸟类的重建就将对更广泛的社区具有巨大的价值，但该项目最终将提供对鸟类进化的更准确的理解，以及是什么推动了它们的巨大多样化。