THE MID-PALAEOZOIC BIOTIC CRISIS: SETTING THE TRAJECTORY OF TETRAPOD EVOLUTION

中古生代生物危机：设定四足动物的进化轨迹

• 批准号: NE/J020729/1
• 负责人: Sarah Davies
• 金额: $ 62.39万
• 依托单位: University of Leicester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ020729%2F1
• 关键词: MID; PALAEOZOIC; BIOTIC; CRISIS; SETTING

This project will shed light on a key stage in the evolution of life on Earth. The advent onto land of limbed vertebrates (tetrapods) was an event that shaped the future evolution of the planet, including the appearance of humans. The process began about 360 million years ago, during the late Palaeozoic, in the early part of the Carboniferous Period. Within the 20 million years that followed, limbed vertebrates evolved from their essentially aquatic and fish-like Devonian predecessors into fully terrestrial forms, radiating into a wide range of body forms that occupied diverse habitats and ecological niches. We know this because we have an adequate fossil record of the earliest limbed vertebrates from the Late Devonian, contrasting with the terrestrial forms that lived significantly later in the Early Carboniferous, about 340 million years ago. It is also clear that a mass extinction event occurred at the end of the Devonian, following which life on land and in fresh water habitats had to be re-established. Unfortunately, the formative 20 million years from the end of Devonian times has remained almost unrepresented for fossil tetrapods and their arthropod contemporaries. Thus, we know little about how tetrapods evolved adaptations for life on land, the environments in which they did so, and the timing or sequence of these events. The evolutionary relationships among these early tetrapods and how they relate to modern forms are also unclear and controversial as a result of this lack of fossil information. The entire fossil hiatus has been called 'Romer's Gap' after the American palaeontologist who first recognized it. Now, for the first time anywhere in the world, several fossil localities representing this period have been discovered in south-eastern Scotland. They have already provided a wealth of new fossils of tetrapods, fish, invertebrates and plants, and our team is the first to have the opportunity to study this material and the environmental, depositional, and climatic context in which this momentous episode took place. We have a number of major aims. The existing fossil material will form a baseline for this study, but the project will augment this by further excavating the richest of the sites so far found and subjecting it to a detailed archaeological-style analysis. We will collect from other recently recognized sites and explore for further sites with relevant potential. The fossil material will be described and analysed using a range of modern techniques to answer many questions related to the evolution of the animals and plants. Not only that, using stratigraphical, sedimentological, palynological, geochemical and isotopic data, we will establish the conditions of deposition that preserved the fossils, the environments in which the organisms lived and died, and the precise times at which they did so. We will drill a borehole that will core through the entire geological formation in which these fossils have been found. Using this, we will integrate data from our fossil sites using the signals provided by the sedimentary record to build a detailed time line showing in which horizons the fossils were found, the age of each occurrence and their sequential relationship. We will compare and correlate our data with that from contemporaneous deposits in Nova Scotia, the only other locality with information sufficiently rich to be meaningful. Our data will allow us to infer changes to the environment and the evolutionary trajectories of the animals and plants during the deposition of this formation, covering the 20 million years following the end-Devonian mass extinction. Comparison with similar data for the Late Devonian will allow us to chart the changes around the time of the mass extinction, to infer its causes and consequences, and obtain a detailed record of exactly how changes to the environment correlated with changes to the fauna and flora.

该项目将揭示地球生命进化的关键阶段。跨越脊椎动物（Tetrapods）的土地的出现是塑造了地球未来演变的事件，包括人类的出现。该过程始于大约36000万年前，即在石炭纪早期的古生代晚期。在随后的2000万年内，狭窄的脊椎动物从本质上是水生和鱼类的泥盆纪前辈演变为完全的陆地形式，散发成各种体形，占据了各种栖息地和生态壁ni的各种体形。我们之所以知道这一点，是因为我们有足够的化石记录，记录了晚期泥盆纪最早的脊椎动物，与大约3.4亿年前的石炭纪早期相比，陆地形式与陆地形式相反。同样很明显，在泥盆纪结束时发生了大规模灭绝事件，随后必须重新建立在陆地和淡水栖息地中的生活。不幸的是，从泥盆纪时代结束后的2000万年成长为2000万年，对于化石四足动物及其节肢动物的同时代人来说，几乎没有代表性。因此，我们对四足动物如何演变在土地上的生命，他们这样做的环境以及这些事件的时机或顺序的情况一无所知。由于缺乏化石信息，这些早期四脚架之间的进化关系及其与现代形式的关系也不清楚和有争议。在美国古生物学家首先认识到它之后，整个化石中断被称为“罗默的差距”。现在，世界上第一次在苏格兰东南部发现了代表这一时期的几个化石地区。他们已经提供了大量的四脚架，鱼类，无脊椎动物和植物的化石，我们的团队是第一个有机会研究这种材料以及发生这种重要事件的环境，沉积和气候环境的机会。我们有许多主要目标。现有的化石材料将构成这项研究的基准，但是该项目将通过进一步挖掘迄今为止发现的最丰富的地点，并将其进行详细的考古风格分析。我们将从其他最近公认的站点收集，并探索具有相关潜力的其他站点。将使用一系列现代技术来描述和分析化石材料，以回答许多与动物和植物进化有关的问题。不仅如此，使用地层，沉积学，孢子学，地球化学和同位素数据，我们还将确定保留化石的沉积条件，生物体生活和死亡的环境以及他们这样做的确切时间。我们将钻一个钻孔，该钻孔将通过发现这些化石的整个地质形成。使用此功能，我们将使用沉积记录提供的信号从化石站点整合数据，以构建详细的时间线，以显示发现化石的地平线，每次发生的年龄及其顺序关系。我们将将我们的数据与新斯科舍省的同期沉积物进行比较和相关联，这是唯一的其他地方，其信息足够丰富，具有有意义的信息。我们的数据将使我们能够推断出这种形成期间动物和植物的环境和进化轨迹的变化，并涵盖了最终devonian质量灭绝后的2000万年。与晚期泥盆纪晚期的类似数据的比较将使我们能够绘制质量灭绝时间周围的变化，以推断其原因和后果，并获得详细的记录，以准确地记录与动物群和动植物的变化相关的环境的变化。

项目成果

A Tournaisian (earliest Carboniferous) conglomerate-preserved non-marine faunal assemblage and its environmental and sedimentological context

图尔奈期（最早的石炭纪）砾岩保存的非海洋动物群及其环境和沉积学背景

• DOI: 10.7287/peerj.preprints.27102v1
• 发表时间: 2018
• 作者: Clack J

Ichnofauna record cryptic marine incursions onto a coastal floodplain at a key Lower Mississippian tetrapod site

• DOI: 10.1016/j.palaeo.2016.12.018
• 发表时间: 2017-02
• 期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
• 作者: C. Bennett;A. Howard;S. Davies;T. Kearsey;D. Millward;P. Brand;M. Browne;E. Reeves;J. Marshall

A lungfish survivor of the end-Devonian extinction and an Early Carboniferous dipnoan radiation

• DOI: 10.1080/14772019.2019.1572234
• 发表时间: 2019-08-07
• 期刊: JOURNAL OF SYSTEMATIC PALAEONTOLOGY
• 影响因子: 2.6
• 作者: Challands, Tom J.;Smithson, Timothy R.;Hill, Henrietta
• 通讯作者: Hill, Henrietta

Early Mississippian sandy siltstones preserve rare vertebrate fossils in seasonal flooding episodes

• DOI: 10.1111/sed.12280
• 发表时间: 2016-10-01
• 期刊: SEDIMENTOLOGY
• 影响因子: 3.5
• 作者: Bennett, Carys E.;Kearsey, Timothy I.;Marshall, John E. A.
• 通讯作者: Marshall, John E. A.

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• DOI: 10.17863/cam.9366
• 发表时间: 2018
• 作者: Clack J