Extinction and Recovery of Crinoids Resulting from Climatic Change during the Ordovician-Silurian Biotic Crisis

海百合（棘皮动物门）是古生代（约5.7亿至2.65亿年前）最重要的海洋生物之一。它们在维持古生代群落的生态结构、棘皮动物的多样性和丰富性以及最终形成今天石灰岩的沉积物贡献方面发挥了主导作用。然而，奥陶世末的全球环境变化导致海百合的大规模灭绝，并最终导致海百合在早志留世多样化的过程中进行了宏观进化重组。奥陶纪末的环境变化是由南部古大陆的大陆冰川作用导致的全球变冷和海平面下降引起的。对奥陶纪末生物危机的透彻理解将为全球环境变化在深时间的后果提供一个重要的例子，与之相比，最近过去发生的全球环境变化和预测未来全球环境变化对海洋的影响。这项建议的目标如下。1)在奥陶系-志留系边界附近的地层（即Ellis Bay组和Becscie组）进行海百合的野外采集和研究。2)同位素分析样品的收集将与加拿大同事的工作相协调，以便尽可能全面地了解这些地层剖面。该计划是对阿什吉利安Vaureal地层进行取样，该地层的同位素尚不清楚，并在该岛东部未取样的部分，对跨越O-S边界的地层进行取样。3)在可用的时间内，整合两组数据集，进一步了解安提科斯蒂岛奥陶系-志留系演替是否完整，或者是否存在影响研究目标的副整合面。4)通过实地考察、实验室研究和撰写论文（本科生和研究生），为本科生和研究生提供研究性学习体验。

Crinoids (Phylum Echinodermata) were among the most important marine organisms throughout the Paleozoic (ca 570 to 265 million years ago). They were dominant in maintaining the ecological structure Paleozoic communities, in diversity and abundance among echinoderms, and in importance as sediment contributors that ultimately led to the limestones of today. However, end-Ordovician global environmental change resulted in a mass extinction of crinoids and, ultimately, a macroevolutionary reorganization of crinoids as they diversified during the Early Silurian. End-Ordovician environmental change was caused by global cooling and sea level lowering resulting from a continental glaciation on the southern paleocontinents. A thorough understanding of the end-Ordovician biotic crisis will provide an important example of the consequences of global environmental change in deep time against which to compare global environmental changes that have occurred in the most recent past and for predicting future oceanic impacts of global environmental change. The objectives of this proposal are the following. 1) Field collection and study of crinoids in strata immediately surrounding the Ordovician-Silurian boundary, i.e. the Ellis Bay and Becscie formations. 2) Collection of samples for isotopic analysis will be coordinated with work by our Canadian colleagues in order to develop as thorough an understanding as possible of these stratigraphic sections. The plan is to sample the Ashgillian Vaureal Formation, for which isotopes are not known, and to take samples in formations that span the O-S boundary in unsampled sections in the eastern part of the island. 3) Within the time available, integrate the two data sets to further develop an understanding of whether the Anticosti Island Ordovician-Silurian succession is complete or whether there are paraconformities present that would affect the objectives of the study being proposed. and 4) provide a research learning experience for undergraduate and graduate students through field studies, laboratory research, and preparation of theses (undergraduate and graduate).