Paleobiological and paleoenvironmental control on the origin and diversification of Late Ordovician and early silurian epicontinental brachiopod faunas of North America

全球变暖的一个主要问题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。在过去的5.3亿年中，全球变暖和海平面上升的两个最大事件之一发生在奥陶纪晚期-志留纪早期（4.6亿~ 4.3亿年前），当时北美古大陆被陆表海淹没，海洋生物在其中蓬勃发展，腕足动物是占主导地位的底栖有壳生物。在这个建议中，丰富的腕足动物化石记录的北美将被研究，以解决几个关键问题，关于陆缘海洋贝类动物群：1）如何陆缘腕足动物群的起源，分散，并在全球变暖和海洋海侵多样化？2)为什么陆表海腕足动物群在晚奥陶世海侵而不是早志留世海侵时发生了分离？3）晚奥陶世-早志留世是什么环境和生物因素控制了同期腕足动物群的分化和生物多样性的时间波动？解决这些问题的方法是比较大陆边缘海（如Anticosti盆地，麦肯齐山脉，加拿大北极）和内陆盆地（哈德逊湾，密歇根州和威利斯顿盆地）之间的腕足动物群，并通过跟踪几个腕足动物谱系的形态变化和他们的古生态环境，使用支序和多变量分析。这项研究的结果可以帮助我们从数百万年尺度的全球变暖和古代地球历史上发生的生物多样性变化的角度更好地理解现代全球变化。

A major concern about the 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. During the past 530 million years (myr) of the Phanerozoic Earth history, one of the two grandest episodes of global warming and sea-level rise occurred in Late Ordovician-Early Silurian time (460-430 myr ago), when the North American paleocontinent was flooded by epicontinental seas, in which marine life thrived, with brachiopods being the dominant benthic shelly organisms. In this proposal, the rich brachiopod fossil records of North America will be studied to address several key questions regarding the epicontinental marine shelly faunas: 1) How did the epicontinental brachiopod faunas originate, disperse, and diversify during the global warming and marine transgression? 2) Why did the epicontinental brachiopod faunas become isolated during the Late Ordovician marine transgression but not during the Early Silurian episode? and 3) What environmental and biological factors controlled the differentiation of contemporaneous brachiopod faunas and the temporal fluctuations in biodiversity during the Late Ordovician-Early Silurian? The approach to these questions is to compare the brachiopod faunas between continental-margin seas (e.g. Anticosti Basin, Mackenzie Mountains, Arctic Canada) and inland basins (Hudson Bay, Michigan, and Williston basins), and by tracing the morphological changes in several brachiopod lineages and their paleoecological settings, using cladistic and multivariate analyses. Results from the proposed research can help us better understand modern global change from the perspective of million year-scale global warming and biodiversity change that occurred in ancient Earth history.