Evolution in morphometric traits in North American Collignoniceratinae (Ammonoidea, Cephalopoda)

概要

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Eight species and one subspecies of two genera of Collignoniceratinae, Collignoniceras and Prionocyclus, are analysed with respect to standard morphological distance measures and ribfrequencies, methods of multivariate statistical analysis, including canonical variate ordination, principal components and generalized distances. It was found that the biostratigraphically inferred evolutionary sequence, as currently perceived, is upheld in detail for the Collignoniceras data. The 'nearest-neighbour' relationships between the Prionocyclus part of the sequence is less complete, although links in main branches are supported. The other aspect given consideration, that of "gracile" and "robust" shells (based on visual inspection of the conch), yielded the result that the subjective assignation of shells to gross morphological type is largely, though not unequivocally, upheld by the statistical analysis. Illustrations of typical representatives of the species analysed are provided.
日本古生物学会の論文
2001-04-27