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/J021067/1
• 负责人: David Millward
• 金额: $ 40.41万
• 依托单位: British Geological Survey
• 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%2FJ021067%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.

这个项目将揭示地球上生命进化的一个关键阶段。四肢脊椎动物(四足动物)出现在陆地上是一件塑造了地球未来进化的事件，包括人类的出现。这一过程大约开始于3.6亿年前，也就是晚古生代，也就是石炭纪早期。在接下来的2000万年里，四肢脊椎动物从它们基本上是水生的、像鱼一样的泥盆纪祖先进化成了完全陆生的形式，辐射到各种身体形式，占据了不同的栖息地和生态环境。我们之所以知道这一点，是因为我们有足够的化石记录，记录了泥盆纪晚期最早的四肢脊椎动物，与生活在大约3.4亿年前的石炭纪早期的陆生脊椎动物形成了鲜明对比。很明显，泥盆纪末期发生了一次大规模灭绝事件，之后陆地和淡水栖息地的生命不得不重新建立起来。不幸的是，从泥盆纪末期开始形成的2000万年，对于化石四足动物和他们的节肢动物同时代人来说，几乎没有代表性。因此，我们对四足动物如何进化以适应陆地生活、它们进化的环境以及这些事件的时间或顺序知之甚少。由于缺乏化石信息，这些早期四足动物之间的进化关系以及它们与现代形式的关系也不清楚，也存在争议。整个化石间隙被称为“罗默缺口”，以第一个发现它的美国古生物学家的名字命名。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点。他们已经提供了丰富的四足动物、鱼类、无脊椎动物和植物的新化石，我们的团队是第一个有机会研究这些材料以及发生这一重大事件的环境、沉积和气候背景的人。我们有一些主要目标。现有的化石材料将构成这项研究的基线，但该项目将进一步挖掘迄今发现的最丰富的遗址，并对其进行详细的考古学风格的分析。我们将从其他最近确认的地点收集数据，并探索其他具有相关潜力的地点。这些化石材料将使用一系列现代技术进行描述和分析，以回答许多与动植物进化有关的问题。不仅如此，我们将利用地层学、沉积学、孢粉学、地球化学和同位素数据，确定保存化石的沉积条件，生物生存和死亡的环境，以及它们这样做的准确时间。我们将钻一个钻孔，在发现这些化石的整个地质构造中取心。利用这一点，我们将利用沉积记录提供的信号整合我们化石遗址的数据，以建立一条详细的时间线，显示发现化石的层位、每次发生的年代及其顺序关系。我们将把我们的数据与新斯科舍省同期矿藏的数据进行比较和关联，新斯科舍省是唯一一个信息足够丰富、有意义的地区。我们的数据将使我们能够推断出这种地层沉积期间环境的变化和动植物的进化轨迹，覆盖了泥盆纪末期大规模灭绝后的2000万年。与晚泥盆世的类似数据进行比较，将使我们能够绘制大灭绝前后的变化图表，推断其原因和后果，并准确地获得环境变化与动植物变化之间关系的详细记录。

项目成果

A fish and tetrapod fauna from Romer's Gap preserved in Scottish Tournaisian floodplain deposits

• DOI: 10.1111/pala.12395
• 发表时间: 2018-10
• 期刊: Palaeontology
• 影响因子: 2.6
• 作者: B. K. A. Otoo;J. Clack;T. Smithson;C. Bennett;T. Kearsey;M. Coates

Norham West Mains Farm Borehole:operations report

诺勒姆西干线农场钻孔：运营报告

• 发表时间: 2013
• 作者: Millward D

The terrestrial landscapes of tetrapod evolution in earliest Carboniferous seasonal wetlands of SE Scotland

苏格兰东南部最早石炭纪季节性湿地四足动物进化的陆地景观

• DOI: 10.1016/j.palaeo.2016.05.033
• 发表时间: 2016
• 期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
• 作者: Kearsey T

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

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.