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Document Type

Research

Keywords

Crinoids; Pennsylvanian, Missourian, Virgilian; Shoemaker Limestone, Haskell Limestone, Cass Formation; Plattsmouth Limestone, Oread Formation; Jackson Park Shale, Stull Shale, Kanwaka Formation; Doniphan Shale, Beil Limestone, Avoca Limestone, Lecompton Formation; Ost Limestone, Tecumseh Formation; Ervine Creek Limestone, Deer Creek Formation; Calhoun Shale. Cass County, Nebraska, Mills, Montgomery, Fremont Counties, Iowa

Abstract

Virgilian age rocks of lowa and Nebraska contain important crinoid faunas and current collections help to establish distributions and tentative ranges of numerous species. A middle limestone-core shale fauna from the Cass Formation of Nebraska provides small, usually inornate species with close Missourian affinities. Other crinoids studied are from outside shales and upper limestones of the cyclothem and these are usually large, ornate species. Biserial arms are reported for the first time for Sublobalocrinus Knapp. The first report of flexible crinoids from Virgilian strata of the Iowa-Nebraska area is made here. Current collections of crinoids contain 40 species and 31 genera representing 19 families: new species or subspecies are; Isoallagecrinus bassleri intermedius, Graffhamierinus gratesquus, Arrectocrinus iowensis, Pyndoxocrinus inornatus, Sublobacrinus kaseri, Contocrinus invaginatus, Apographiocrinus platybasis. The species Aesiocrinus luxuris is referred to the genus Moundocrinus.

Publication Date

March 1980

Journal Title

Proceedings of the Iowa Academy of Science

Volume

97

Issue

1

First Page

1

Last Page

19

Copyright

© Copyright 1980 by the Iowa Academy of Science, Inc.

Language

EN

File Format

application/pdf

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