On the origin systematic position of the calcareous-shelled inarticulate brachiopods |
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Authors: | Wladimir Ju Gorjansky Leonid Ye Popov |
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Institution: | PGO 'Sevzapgeologia', Hercen st. 59, Leningrad, 190 000, U.S.S.R.;VSEGEI, Srednij pr. 74, Leningrad, 199 026, U.S.S.R. |
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Abstract: | Available data on the anatomy, ontogeny embryology of Brachiopoda ( sensu lato ) suggest that this Phylum in the traditional view is in fact a clade of organization includes two stocks of lophophorate organisms of quite different origins. Their rank does not correspond to existing Class divisions. The phosphatic-shelled in articulates are regarded as a separate Class Lingulata. The Phylum Brachiopoda ( sensu stricto ) is restricted to the calcareous-shelled inarticulate articulate lineages. Ancestors of the calcareous-shelled brachiopods probably differentiated from the protolophophorates before the radiation of the other lophophorate stocks took place. The articulation of the valves appeared independently in several lineages during the early stages of brachiopod evolution. |
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Keywords: | Brachiopoda Inarticulata Arriculata Lingulata phylogeny anatomy functional morphology |
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