文章基本信息

标题：Alleged cnidarian Sphenothallus in the Late Ordovician of Baltica, its mineral composition and microstructure
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作者：OLEV VINN ; KALLE KIRSIMÄE
期刊名称：Acta Palaeontologica Polonica
印刷版ISSN：0567-7920
电子版ISSN：1732-2421
出版年度：2015
卷号：60
期号：4
页码：1001-1008
DOI：10.4202/app.00049.2013
语种：English
出版社：Institute of Paleobiology PAS
摘要：Sphenothallus is a problematic fossil with possible cnidarian affinities. Two species of Sphenothallus, S. aff. longissimus and S. kukersianus, occur in the normal marine sediments of the Late Ordovician of Estonia. S. longissimus is more common than S. kukersianus and has a range from early Sandbian to middle Katian. Sphenothallus had a wide paleo-biogeographic distribution in the Late Ordovician. The tubes of Sphenothallus are composed of lamellae with a homo-geneous microstructure. The homogeneous microstructure could represent a diagenetic fabric, based on the similarity to diagenetic structures in Torellella (Cnidaria?, Hyolithelminthes). Tubes of Sphenothallus have an apatitic composition, but one tube contains lamellae of diagenetic calcite within the apatitic structure. Sphenothallus presumably had origi-nally biomineralized apatitic tubes. Different lattice parameters of the apatite indicate that biomineralization systems of phosphatic cnidarians Sphenothallus and Conularia sp. may have been different.
关键词：Cnidaria?;Sphenothallus;apatite;microstructure;Ordovician;Sandbian;Katian;Estonia