A cladistic analysis of the anomalocystitid mitrates |
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Authors: | MARCELLO RUTA |
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Institution: | Department of Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX and Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD |
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Abstract: | A cladistic analysis of the anomalocystitid mitrates is presented. A neutral terminology for the anomalocystitid skeleton is proposed, independent of the zoological interpretation of the fossils as echinoderms or as craniates. The anomalocystitid monophyly is supported by parsimony, although the instability of several basal taxa makes it difficult to ascertain the sequence in which characters were acquired or modified in the transition from the mi-trocystitids to the anomalocystitids. The genus Barrandeocarpus falls outside the anomalocystitids as traditionally defined in the literature, and is either polyphyletic or monophyletic. Diamphidiocystis drepanon is either a basal anomalocystitid or the sister taxon to the group ( Enoploura popei + Allanicytidiidae). Ateleocystites guttenbergensis is placed either at the base of the anomalocystitids or as the sister taxon to a group including mainly boreal forms, the only non-boreal members being the South African Bokkeveldia oosthuizeni and the Australian Victoriacystis wilkinsi. |
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Keywords: | characters coding homology plates mitrocystitids Allanicytidiidae Gondwana |
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