Collaborative Research: Systematics, Paleoecology, and Extinction of Late Osagean Crinoids from Iowa, Illinois and Missouri

拟议的研究包括对奥萨吉晚期（密西西比）基奥卡克石灰岩和爱荷华州、伊利诺伊州和密苏里州华沙组基底部分的海红石进行详细的系统修正，并研究它们的沉积环境。基奥卡克和华沙基底的海百合在本世纪下半叶还没有得到研究，尽管事实上在其他地区这个时代的海百合已经被很好地了解了，这些动物来自密西西比纪的北美标准剖面。对这些动物群的重新评价将使我们对整个东部晚欧塞古时期海蚕类动物群的系统学、群落古生态学和沉积发生地的理解更加完整。美国中部。这反过来又将使我们能够解释导致晚期奥萨吉海百合分布的制约因素和控制因素。我们将根据环境控制模型对这些新数据进行测试，该模型是基于对印第安纳州和肯塔基州博登三角洲复合体的晚奥萨吉世海牡丹动物群的多变量分析。对奥萨吉世晚期海百合控制因素的记录是对古生代海百合基本认识的必要条件。奥塞吉时期是海百合种类最丰富的时期，然而在奥塞吉末期，海百合遭受了极度的灭绝。欧沙末灭绝后的海鲷类动物群在分类特征上有很大差异，从灭绝事件后的恢复到古生代末大灭绝，海鲷类动物群的分类特征基本保持不变。该研究结果为提出古生代海百合演化的更大问题提供了前提条件。

The proposed study involves both a detailed systematic revision of the crinoids from the late Osagean (Mississippian) Keokuk Limestone and the basal part of the Warsaw Formation in Iowa, Illinois, and Missouri, and a study of their depositional settings. Crinoids from the Keokuk and basal Warsaw have not received study in the latter half of this century, despite the fact that crinoids of this age in other areas are well understood, and these faunas are from the North American Standard Section of the Mississippian. Re.evaluation of these faunas will complete our understanding of the systematics, community paleoecology, and depositional occurrences of crinoid faunas from the late Osagean throughout the east.central United States. This in turn will enable us to interpret the constraints and controlling factors that were responsible for the distribution of late Osagean crinoids. We will test these new data against the environmental controls model, which is based on multivariate analysis of late Osagean crinoid faunas from the Borden deltaic complex in Indiana and Kentucky. Documentation of controlling factors operating on late Osagean crinoids is essential for a fundamental understanding of Paleozoic crinoids. The Osagean was witness to the maximum diversity known among crinoids, and yet at the close of the Osagean, crinoids suffered extreme extinction. Crinoid faunas after the terminal Osagean extinction were very different in taxonomic character and remained basically the same from the recovery following the extinction event until the terminal Paleozoic mass extinction. Results from the proposed study are prerequisite for posing larger questions on the evolution of Paleozoic crinoids.