Streptoiocrinus gen. nov. (Disparida, Crinoidea) from the Lower and Middle Ordovician of the Leningrad Region, and Fluctuating Asymmetry of Radial Symmetry

被引：1
|
作者：
Rozhnov, S. V. [1 ]
机构：
[1] Russian Acad Sci, Borissiak Paleontol Inst, Moscow 119647, Russia
来源：
PALEONTOLOGICAL JOURNAL | 2020年 / 54卷 / 07期
基金：
俄罗斯科学基金会;
关键词：
Echinoderms; crinoids; disparids; crown; stem; morphology; symmetry; fluctuating asymmetry; Ordovician; Floian; Dapingian; Baltic;
D O I：
10.1134/S0031030120070114
中图分类号：
Q91 [古生物学];
学科分类号：
0709 ; 070903 ;
摘要：
A crown of Streptoiocrinus gen. nov., with its articulated stem, the columnals of which have long been known in the Billingen and Volkhov regional stages (Floian and Dapingian stages) of the Leningrad Region and Estonia are described. A detailed study of the crown and stem morphology showed that the new genus belongs to the disparid crinoid superfamily Iocrinacea. This genus is the first mass crinoid invader into the Ordovician Baltic paleobasin. The fluctuating asymmetry in the manifestation of the pentaradial symmetry of the stem columnals is described.
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页码：704 / 714
页数：11
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