The Morphologic History of Paleozoic-Triassic Ammonoids

古生代-三叠纪菊石的形态史

• 批准号: 9706232
• 负责人: W. Bruce Saunders
• 金额: $ 13.43万
• 依托单位: Bryn Mawr College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2001-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9706232&HistoricalAwards=false
• 关键词: Morphologic; History; Paleozoic; Triassic; Ammonoids

9706232 Saunders The proposed research will focus on three major themes concerning Paleozoic-Triassic ammonaid cephalopods: 1. Analysis of variation in suture-inclusive, whole-shell morphology and morhphologic diversity through space and time (Devonian-Triassic), using principal components analysis (PCA) of a 21-character set for each taxon; 2. The evolution of ammonoid suture complexity through time, as a single-character measure of biological complexity, and with respect to evolution of suture complexity in different ammonoid clades; and 3. The effects of extinction events on ammonoid morphospace, and on morphologic and taxonomic diversity, focusing on three major crises: the U. Devonian Frasnian/Famennian, the Devonian/Carboniferous, and the Permian/Triassic. The scope is unprecedented in ammonoid investigations, in terms of (a) its time span (~190 my); (b) the comprehensive treatment of all 627 Paleozoic ammonoid genera (212 Devonian, 263 Carboniferous, 152 Permian) plus an additional subset of 25-30 genera (75-100 species) of basal Triassic ammonoids. Additionally, in order to precisely evaluate the timing of major extinction's and to assess susceptibility, persistence, and recurrence of shell morphotypes to these events, we will undertake PC analysis of variation in a combined total of 700-750 species (~150 genera) present during the ca. 0.5-5 my intervals spanning each of the three extinction episodes. This research will be the most complete morphometric treatment of Paleozoic and early Mesozoic cephalopods ever undertaken. It will generate a 21+ character morphometric data-set for more than 600 ammonoid genera and an additional 700+ species that is taxonomically up-to-date, complete and stratigraphically precise. The time-stepped analysis by PCA will permit documentation of how clades evolved, changed in morphologic diversity and richness, and how they responded to biotic crises. The results will have bearing on the interpretation of macro-evolutionary change, the evo lution of complexity, the influence of morphologic constraints and extinction events on variation and diversity, all on a time scale of nearly 200 million years.

9706232 Saunders 拟议的研究将集中于古生代-三叠纪铵类头足类动物的三个主要主题： 1. 对每个分类单元的 21 个字符集使用主成分分析 (PCA)，分析缝合线、全壳形态和形态多样性随时间和空间的变化（泥盆纪-三叠纪）； 2. 菊石缝合线复杂性随时间的演变，作为生物复杂性的单特征测量，以及不同菊石进化枝中缝合线复杂性的演化； 3.灭绝事件对菊石形态空间以及形态和分类多样性的影响，重点关注三大危机：泥盆纪弗拉斯尼纪/法门纪、泥盆纪/石炭纪和二叠纪/三叠纪。 菊石研究的范围是前所未有的，就以下方面而言：(a) 时间跨度（~190 my）； (b) 综合处理所有 627 个古生代菊石属（212 个泥盆纪、263 个石炭纪、152 个二叠纪）以及另外 25-30 个属（75-100 种）基础三叠纪菊石。 此外，为了精确评估主要灭绝的时间，并评估贝壳形态类型对这些事件的敏感性、持久性和复发性，我们将对大约 700-750 个物种（约 150 个属）的变异进行 PC 分析。 0.5-5 我的间隔跨越三个灭绝事件中的每一个。 这项研究将是迄今为止对古生代和早期中生代头足类动物最完整的形态测量研究。 它将为 600 多个菊石属和另外 700 多个物种生成超过 21 个字符的形态测量数据集，该数据集在分类学上是最新的、完整的且地层学上精确的。 PCA 的时间步进分析将允许记录进化枝如何进化、形态多样性和丰富度的变化，以及它们如何应对生物危机。 结果将影响对宏观进化变化、复杂性进化、形态限制和灭绝事件对变异和多样性的影响的解释，所有这些都在近2亿年的时间尺度上进行。