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Ordovician Calceocrinids from Northern Iowa and Southern Minnesota

James C. Brower and Harrell L. Strimple
Journal of Paleontology
Vol. 57, No. 6 (Nov., 1983), pp. 1261-1281
Stable URL: http://www.jstor.org/stable/1304813
Page Count: 21
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Ordovician Calceocrinids from Northern Iowa and Southern Minnesota
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Abstract

Seven calceocrinid species are described from the Middle and Upper Ordovician of northern Iowa and southern Minnesota. These taxa are: Calceocrinus levorsoni n. sp. from the Maquoketa Formation; C. gossmani n. sp., Cremacrinus gerki n. sp., C. guttenbergensis Kolata, and C. sp. aff. C. arctus Sardeson from the Dunleith Formation; C. punctatus Ulrich of the Decorah Shale; and C. crossmani n. sp. from the Platteville Limestone. These species shed some light on the life style and functional morphology of calceocrinids. A young specimen of Calceocrinus gossmani n. sp. definitely had a runner mode of life in which the stem was parallel to the substrate. The hinge, which opened and closed the crown, comprises a unique character of calceocrinids. Examination of C. levorsoni n. sp. indicates that the hinge was probably closed with ligaments rather than muscles. The ligaments along the anterior margin of the hinge exhibited strong positive allometry in response to the problems of opening the hinge and raising the crown into the erect or feeding position. Cremacrinus crossmani n. sp. most likely formed a planar filtration fan which was efficient for trapping food particles that were carried parallel to the seafloor by currents.

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