A View from the Other Side of the World: Middle Triassic Ichthyosaurs of Nevada and Their Implications for the Initial Phase of the Mesozoic Marine Revolution in the Eastern Pacific Realm

世界另一边的观点：内华达州中三叠世鱼龙及其对东太平洋地区中生代海洋革命初始阶段的影响

• 批准号: 388659338
• 负责人: Professor Dr. Martin Sander
• 金额: --
• 依托单位: Museum für Naturkunde - Leibniz-Institut für Evolutions- und Biodiversitätsforschung (MfN)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/388659338?language=en
• 关键词: View; Other; Side; World; Middle

The Early and Middle Triassic represent crucial time periods for our understanding of the organization and evolution of ecosystem because it represents the time the modern ecosystem structure was established after the most devastating extinction event in Earth history at the end of the Permian. In the marine realm, secondarily aquatic reptiles, in particular ichthyosaurs and sauropterygians, radiated quickly and are considered key elements of the so called Mesozoic Marine Revolution (MMR) during which a reorganization of marine trophic webs towards their modern structure took place. While much data has been gathered on the shallow-water environments of the Tethys realm, comparatively little is known on the open water fauna of the Pacific realm, leaving a significant gap in our knowledge of this crucial phase of vertebrate evolution. Here we seek to address this and gap in order to gain a comprehensive picture of the faunal differences between the Tethys and Pacific realms. This forms the foundation for a true understanding of the recovery and structuring of marine ecosystems after the P/T extinction events and the associated biogeographic patterns. Our work involves several approaches, field- and collections-based. We propose to systematically prospect the unexplored fossiliferous Middle Triassic Fossil Hill Member outcrops in the Augusta Mountains in Central Nevada which promise to yield further highly relevant finds of marine reptiles of the open water environment in the Pacific realm. Previous field seasons have yielded well-preserved skeletons of a medium-sized pregnant ichthyosaur as well as the anterior third of the skeleton of a giant ichthyosaur (skull length 1.95 m). This spectacular specimen differs from Thalattoarchon, the first macropredator among secondarily aquatic tetrapods, in the even larger size and particularly the piscivorous dentition. In combination with a reevaluation of mixosaurid and cymbospondylid ichthyosaurs from the Fossil Hill Member of both the classical Humboldt Range and the Augusta Mountains, anatomical description of these new specimens will provide important data for understanding morphological disparity and reproductive strategies in early ichthyosaurians. A phylogenetic analysis will provide the foundation for a detailed discussion of early ichthyosaurian evolution as well as further analyses of the biogeography and ecosystem structures. Systematic work will be followed by an analysis of trophic relationships because these play an integral role in the establishment of the ecosystem and the radiation of marine reptiles. The project will integrate closely with another project already funded by the DFG, the investigation of the ammonoid fauna and biostratigraphy of the Fossil Hill Member.

早三叠世和中三叠世是我们理解生态系统组织和演化的关键时期，因为它代表了在二叠纪末地球历史上最具破坏性的灭绝事件之后现代生态系统结构建立的时间。在海洋领域，其次是水生爬行动物，特别是鱼龙和蜥脚类，辐射迅速，被认为是所谓中生代海洋革命（MMR）的关键要素，在此期间，海洋营养网向现代结构进行了重组。虽然已经收集了有关特提斯区域浅水环境的大量数据，但对太平洋区域开放水域动物群的了解相对较少，这使得我们对脊椎动物进化的这一关键阶段的了解存在巨大差距。在这里，我们寻求解决这个问题和差距，以便全面了解特提斯和太平洋领域之间的动物区系差异。这为真正了解 P/T 灭绝事件后海洋生态系统的恢复和结构以及相关的生物地理模式奠定了基础。我们的工作涉及多种方法，基于实地和基于集合。我们建议系统地勘探内华达州中部奥古斯塔山脉中未勘探的中三叠世化石山部分露头，这有望在太平洋地区的开放水域环境中进一步发现高度相关的海洋爬行动物。之前的野外季节已经发现了保存完好的中型怀孕鱼龙骨骼以及巨型鱼龙骨骼的前三分之一（头骨长1.95 m）。这个壮观的标本与第二水生四足动物中第一个大型捕食者 Thalattoarchon 的不同之处在于它的体型更大，尤其是鱼食性牙列。结合对经典洪堡山脉和奥古斯塔山脉化石山部分的混合龙科和圆椎鱼龙科的重新评估，这些新标本的解剖学描述将为了解早期鱼龙类的形态差异和繁殖策略提供重要数据。系统发育分析将为详细讨论早期鱼龙进化以及进一步分析生物地理学和生态系统结构提供基础。系统工作之后将分析营养关系，因为这些关系在生态系统的建立和海洋爬行动物的辐射中发挥着不可或缺的作用。该项目将与 DFG 资助的另一个项目紧密结合，即对化石山成员的菊石动物群和生物地层学进行调查。

项目成果

Structural, functional, and physiological signals in ichthyosaur vertebral centrum microanatomy and histology

• DOI: 10.5252/geodiversitas2018v40a7
• 发表时间: 2018-04-12
• 期刊: GEODIVERSITAS
• 影响因子: 1.8
• 作者: Houssaye, Alexandra;Nakajima, Yasuhisa;Sander, P. Martin
• 通讯作者: Sander, P. Martin

Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans

• DOI: 10.1126/science.abf5787
• 发表时间: 2021-12
• 期刊: Science
• 影响因子: 56.9
• 作者: P. Sander;E. Griebeler;N. Klein;Jorge Velez Juarbe;T. Wintrich;L. Revell;L. Schmitz

A new cymbospondylid ichthyosaur (Ichthyosauria) from the Middle Triassic (Anisian) of the Augusta Mountains, Nevada, USA

• DOI: 10.1080/14772019.2020.1748132
• 发表时间: 2020-04-20
• 期刊: JOURNAL OF SYSTEMATIC PALAEONTOLOGY
• 影响因子: 2.6
• 作者: Klein, Nicole;Schmitz, Lars;Sander, P. Martin
• 通讯作者: Sander, P. Martin