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The Anisian (Middle Triassic) ammonoids of Nevada - An integrated approach to understand morphological change

内华达州的阿尼西期（中三叠世）菊石 - 了解形态变化的综合方法

基本信息

批准号：
321792813
负责人：
Professor Dr. Jens Lehmann
金额：
--
依托单位：
Keck Graduate Institute of Applied Life Sciences
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/321792813?language=en
关键词：
Anisian Middle Triassic ammonoids Nevada

项目摘要

In the Anisian stage of the early Middle Triassic ammonoid variability is high off the western coast of Panthalassa and the taxonomic and morphological diversity is remarkable. Superb outcrops in NWNevada in the United States provide the best insight into open water faunas of this part of the world. Thus our approach is characterized by an overall design as a primarily high quantity approach. The largest part of the material can be collected from the spacious outcrops in the desert of Nevada, but the data set is planned be completed by collections of one of our co-operation partner in California and by those parts of the National Museum collection in Washington that are suitable for our approach. Our proposal aims to elucidate the complex interplay between morphological disparity in ammonoids, environmental change, predation stress expressed by bite marks as well as indirect morphological change by adaption. We plan to use multivariate statistics (PAST, R) to discriminate between shell morphologies to obtain a comprehensive view of variability. Based on the taxonomic and morphologic diversity change in the sections we expect to unravel the expected morphological change through time and to elucidate evolutionary pathways. The later will be possible also by support of one of our American co-operation partners who is highly qualified in testing evolutionary hypotheses. Our overall research topic is strongly connected to the Mesozoic Marine Revolution (MMR) that started after the Permian/Triassic boundary with a full reorganisation of ecosystems. The intense radiation of ammonoids in the Triassic, constituting a main portion of macroscopic biomass and falls together with a new development of their potential predators. Among marine reptiles Omphalosaurus was possibly specialised in shell crushing according to this peculiar jaw and teeth organization, and are focussed on in the proposals applied for simultaneously by the Bonn and Berlin working-groups. The compound view of our proposal is added by an assessment of the developmental background of morphological change by a fluctuating asymmetry analysis. This is projected to be based on geometric morphometric methods (including landmarks), enabled by three-dimensional models. The latter we intend to generate from the photogrammetry of ammonites.

在中三叠世早期的Anisian阶段，泛地中海西岸的菊石变化很大，分类和形态多样性显着。美国内华达州西北部的极好的露头提供了对世界这一地区的开放水域动物群的最佳洞察。因此，我们的方法的特点是整体设计作为一个主要的高质量的方法。大部分材料可以从内华达州沙漠中的开阔露头中收集，但数据集计划由我们在加州的一个合作伙伴的收藏品和华盛顿国家博物馆收藏的适合我们方法的部分来完成。我们的提案旨在阐明菊石形态差异、环境变化、咬痕表达的捕食应激以及适应引起的间接形态变化之间复杂的相互作用。我们计划使用多元统计（PAST，R）来区分壳形态，以获得变异性的全面视图。基于分类和形态多样性的变化，我们希望解开预期的形态变化，随着时间的推移，并阐明进化途径。后者也将有可能得到我们的一个美国合作伙伴的支持，他在测试进化假说方面非常合格。我们的整体研究主题与二叠纪/三叠纪边界后开始的中生代海洋革命（MMR）密切相关，生态系统全面重组。菊石在三叠纪的强烈辐射，构成了宏观生物量的主要部分，福尔斯与它们的潜在捕食者的新发展一起下降。在海洋爬行动物中，根据这种特殊的颚和牙齿组织，鸭嘴龙可能专门从事贝壳破碎，并在波恩和柏林工作组同时申请的提案中集中讨论。通过波动不对称分析对形态变化的发展背景进行评估，增加了我们提案的复合观点。这预计将基于几何形态测量方法（包括地标），由三维模型启用。后者我们打算从菊石的摄影测量中产生。