Morphology, growth and taxonomy of the Ordovician rhombiferanCaryocystites
作者:
JohanFredrik Bockelie,
期刊:
Geologiska Föreningen i Stockholm Förhandlingar
(Taylor Available online 1982)
卷期:
Volume 103,
issue 4
页码: 499-513
ISSN:0016-786X
年代: 1982
DOI:10.1080/11035898209453727
出版商: Taylor & Francis Group
关键词: Rhombifera;Caryocystites;morphology;growth;taxonomy;Sweden
数据来源: Taylor
摘要:
Caryocystiteshas five peri-oral plates, as in other members of the superfamily, and a primitive stem with five pentameres. Evolutionary trends include addition of ambulacra, greater regularity in plate distribution and increasing complexity in the development of respiratory pores. InCaryocystites thorslundin.sp. young specimens have only four primary circlets of thecal plates; the peri-oral, peri-gonal, periproctal and basal. Thecal enlargement was accomplished by accretional growth of primary plates and the addition of new thecal plates intercalated between the original four plate circlets.Caryocystitesevolved in the early Middle Ordoviciap and became extinct at the end of the Ordovician. The morphology and evolutionary trends are similar to those of the other caryocystitids. Seven species from Sweden are described morphologically and taxonomically, including three new ones (C. valdari, C. rugosus, C. thorslundi).
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