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The brachiopods Alwynella and Grorudia: homeomorphic plectambonitoids in the Middle and Upper Ordovician of Baltoscandia

Published online by Cambridge University Press:  01 September 2007

Linda Hints  and
David A. T. Harper
Linda Hints
Affiliation:
Institute of Geology, Tallinn University of Technology, 5 Ehitajate tee, 19086 Tallinn, Estonia. E-mail: Linda.Hints@gi.ee
David A. T. Harper
Affiliation:
Geological Museum, University of Copenhagen, Øster Voldgade 5–7, DK 1350 Copenhagen, Denmark. E-mail: dharper@snm.ku.dk
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Abstract

Two Ordovician plectambonitoid genera, Alwynella and Grorudia, occur in drill core sections of Latvia in the East Baltic, and in exposures and loose blocks on the Swedish Island of Öland in the Baltic Sea. The new material confirms differences between the two taxa that are assigned herein to separate families, Alwynellidae fam. nov. and Grorudiidae Cocks & Rong, 1989. In particular, the undercut cardinalia separates Alwynella from Grorudia and indicates its proximity to the sowerbyellids. The genus Grorudia, which is externally similar to Alwynella, is more closely related to the palaeostrophomenines. A new species Grorudia morrisoni sp. nov. is established in the East Baltic. The specimens from Öland are included tentatively within the genus Grorudia due to lack of interiors. Both Alwynella and Grorudia were confined to deeper-water facies in the Baltic palaeobasin, within successions ranging in age from latest Mid (late Llanvirn) to earliest Late Ordovician (mid Caradoc).

Keywords

East Balticnew family and speciesphylogenytaxonomy
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 98 , Issue 3-4: Brachiopod Research into the Third Millenium , September 2007 , pp. 271 - 280
Copyright
Copyright © Royal Society of Edinburgh 2008

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