Geometric Morphometric Analysis and Taxonomic Revision of the Gzhelian (Late Pennsylvanian) Conodont Idiognathodus simulator from North America
Geometric Morphometric Analysis and Taxonomic Revision of the Gzhelian (Late Pennsylvanian) Conodont Idiognathodus simulator from North America
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DOI：
10.4202/app.00198.2015
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发表时间：
2016-02
影响因子：
1.8
通讯作者：
N. Hogancamp;J. Barrick;R. Strauss
中科院分区：
文献类型：
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作者：
N. Hogancamp;J. Barrick;R. Strauss
一种新的形态测量方法被开发来研究P1元素内的形态变化，通常被称为Idiognathodus模拟器，这被选为全球Gzhelian阶段（石炭纪）的生物地层标志。这种新的方法结合了基于标志的几何形态测量学和特征分析来分析I.模拟器组，并可用于分析形状变化的其他形态相似的牙形刺组。所分析的样品取自北美大陆中部地区奥里德旋回层的早格日期希伯纳页岩的三个剖面。模拟器最初被命名为。分析表明，I.模拟组包括一组至少五个物种，具有不对称的P1元件对，相对短的侧龙骨脊，和不对称发展的偏心槽。种的鉴别是基于尾叶和喙叶的存在，侧隆脊的特征和平台的形状。物种I。模拟器仅限于P1元件，其尾侧隆突脊与尾侧平台边缘隔离。Idiognathodus lateralis sp. nov.的直立，包括P1元素与尾侧隆脊，这不是从尾平台边缘隔离。
A new morphometric approach was developed to study morphological variation within P1 elements commonly referred to as Idiognathodus simulator, which was selected to be the biostratigraphic marker for the base of the global Gzhelian Stage (Carboniferous). This new approach combines landmark-based geometric morphometrics with eigen analyses to analyze shape variation within P1 elements of the I. simulator group, and could be used to analyze shape variation in other morphologically similar conodont groups. Specimens analyzed were obtained from three sections of the early Gzhelian Heebner Shale of the Oread cyclothem in the North American Midcontinent region, the cyclothem from which I. simulator was originally named. This analysis shows that the I. simulator group comprises a set of at least five species with asymmetrical P1 element pairs, relatively short adcarinal ridges, and a variably developed eccentric groove. Species discrimination is based on the presence of caudal and rostral lobes, character of the adcarinal ridges, and platform shape. The species I. simulator is restricted to P1 elements with a caudal adcarinal ridge that is isolated from the caudal platform margin. Idiognathodus lateralis sp. nov. is erected to include P1 elements with a caudal adcarinal ridge that is not isolated from the caudal platform margin.