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A well-preserved and locally abundant crinoid fauna has been discovered in the lower part of the Champlainian (Middle Ordovician) Glenhaven Member of the Guttenberg Formation in the Upper Mississippi Valley region. The material consists of the dicyclic inadunates Cupulocrinus levorsoni n. sp., C. jewetti (E. Billings) and monocyclic camerate Pycnocrinus gerki n. sp.
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Dennis R. Kolata (1986) studied this question.
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