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Additional information on Alainaspis and Boothiaspis, cyathaspidids (Agnatha: Heterostraci) from the Upper Silurian of Northwest Territories, Canada

Published online by Cambridge University Press:  20 May 2016

David K. Elliott  and
David L. Dineley
David K. Elliott
Affiliation:
Department of Geology, Box 6030, Northern Arizona University, Flagstaff 86011
David L. Dineley
Affiliation:
Department of Geology, University of Bristol, Avon BS8 1TR, England
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Abstract

New material of the poraspid Alainaspis platyrhina Elliott and Dineley has made it possible to provide a more extensive reconstruction of this animal. It is now clear that an elongated branchial opening was present below the lateral lamina and that a well-developed post-branchial lobe was present. No branchial plate has been identified and this may have been fused to the dorsal shield, forming the ventral lamina. The lateral lamina is now seen to terminate in a rounded angle before the posterior margin of the shield. Several ventral shields with similar ornament are identified as belonging to A. platyrhina. These are broad and deep and are consistent with the original interpretation of this animal as a filter feeder. One similar shield with a coarser ornament is tentatively assigned to the closely related species Boothiaspis ovata Broad.

Type
Research Article
Information
Journal of Paleontology , Volume 65 , Issue 2 , March 1991 , pp. 308 - 313
Copyright
Copyright © The Paleontological Society 

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