Late Ordovician brachiopod faunal endemism and mass extinction during drastic climate change, ocean anoxia and sea-level fluctuations

剧烈气候变化、海洋缺氧和海平面波动期间奥陶世晚期腕足动物特有现象和大规模灭绝

• 批准号: RGPIN-2014-04075
• 负责人: Jin, Jisuo
• 金额: $ 2.19万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587587
• 关键词: Late; Ordovician; brachiopod; faunal; endemism

Our concern about global warming today is its effect on sea level rise and biodiversity change. The study of modern global change in climate and biodiversity is confined to the scale of decade to millennium. Paleontologists investigate environmental and biodiversity changes in Earth history at a million-year scale based on fossil record preserved in sedimentary rocks and thus provide unique and valuable data and interpretations to complement studies on modern and recent global change. During the past 530 million years (myr) of the Phanerozoic Earth history, one of the two grandest episodes of global sea-level rises occurred in the Late Ordovician (460–443 myr ago), when much of North America was flooded by epicontinental seas, in which marine life thrived, with brachiopods being the dominant benthic shelly organisms. This was followed by a terminal Ordovician glaciation and mass extinction event. In this proposal, the rich brachiopod fossil record of North America will be studied to determine the responses of Late Ordovician marine benthic shelly faunas to drastic sea level changes. In particular, the following questions will be addressed: 1) How did the continental-margin brachiopod faunas give rise to, and was subsequently replaced by, the epicontinental-sea faunas during the Late Ordovician sea level highstand? 2) Why did the epicontinental brachiopod faunas become highly endemic during the Late Ordovician marine transgression but not during some other similarly high sea-level? and 3) Why did the terminal Ordovician glaciation cause a mass extinction, whereas other major glaciations did not? The approach to these questions is to trace the brachiopod evolution at the species, genus, community, and faunal levels from both continental-margin (e.g. Anticosti Basin, Cincinnati Arch, Mackenzie Mountains) to inland-basin (Hudson Bay, Michigan, and Williston basins) depositional environments through the Late Ordovician sea-level fluctuations, using cladistics, multivariate and other numerical analyses. Results from the proposed research can help us better understand modern global change from the perspective of million year-scale global climate-biodiversity changes in Earth history.

我们今天对全球变暖的关切是它对海平面上升和生物多样性变化的影响。现代全球气候和生物多样性变化的研究仅限于十年到千年的尺度。古生物学家根据保存在沉积岩中的化石记录，以百万年的规模研究地球历史中的环境和生物多样性变化，从而提供独特而有价值的数据和解释，以补充现代和最近全球变化的研究。在过去的5.3亿年（百万年）的中生代地球历史中，全球海平面上升的两个最大事件之一发生在奥陶纪晚期（4.6亿~ 4.43亿年前），当时北美大部分地区被陆表海淹没，海洋生物蓬勃发展，腕足动物是占主导地位的底栖有壳生物。随后是奥陶纪末期的冰川作用和大规模灭绝事件。在这项建议中，将研究北美丰富的腕足动物化石记录，以确定晚奥陶世海洋底栖甲壳动物群对海平面急剧变化的反应。特别是，以下问题将得到解决：1）大陆边缘腕足动物群如何产生，并随后被取代，在晚奥陶纪海平面高水位的表海动物群？2)为什么陆缘腕足动物群在晚奥陶世海侵期间而不是在其他类似的高海平面期间成为高度特有的？3）为什么奥陶纪末冰期导致了大灭绝，而其他主要冰期没有？这些问题的方法是追溯腕足动物的进化在物种，属，社区和动物群水平从大陆边缘（如Anticosti盆地，辛辛那提拱，麦肯齐山）到内陆盆地（哈德逊湾，密歇根州和威利斯顿盆地）沉积环境通过晚奥陶纪海平面波动，使用分支，多元和其他数值分析。这项研究的结果可以帮助我们从地球历史上百万年尺度的全球气候-生物多样性变化的角度更好地理解现代全球变化。