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Publication Type
Journal Article
UWI Author(s)
Author, Analytic
Donovan, S.K.,; Pickerill, R.K.; Mikulic, D.G.; Kluessendorf, J.
Author Affiliation, Ana.
Geography and Geology; Faculty of Pure and Applied Sciences
Article Title
Upright crinoids of the Thornton Reef, Wenlock (Silurian) of Illinois, U.S.A.
Medium Designator
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Connective Phrase
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Journal Title
Geological Journal
Translated Title
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Reprint Status
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Date of Publication
1996
Volume ID
31
Issue ID
4
Page(s)
369-378
Language
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Connective Phrase
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Location/URL
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ISSN
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Notes
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Abstract
The rare preservation of columns perpendicular to bedding may provide convincing evidence that ancient crinoids adopted an upright attitude during life. However, taphonomic and sedimentological analyses are important in determining whether such occurrences are truly in situ or represent unusual allochthonous accumulations. The Crinoid Biosome of the Thornton Reef Complex includes pluricolumnals preserved perpendicular to bedding, in association with more common specimens parallel or angled to bedding. Upright pluricolumnals are relatively shorter (<150 mm) than the longest non-upright specimens; they sometimes occur as imbricate accumulations and lack attachment structures (although these are preserved separately). Brachiopod valves and colonial corals may also be preserved perpendicular to bedding. These features suggest that the Thornton beds were formed as viscous mass flow deposits and that the upright crinoid columns are allochthonous or, at best, parautochthonous.....
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Keywords
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