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Paleontological Research
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Abstract
Abstract.
A metric analysis of the morphology of two related Eocene species (Podocyrtis sinuosa and P. mitra) that are part of the Lampterium evolutionary lineage was undertaken in order to evaluate hypotheses related to their mutual taxonomic distinction statistically. All analyses (landmark, outline semi-landmark and landmark-constrained outlines) support an interpretation of statistically significant species-specific shape differences. Moreover, landmark and semilandmark-based morphometric characterizations can be used to identify which regions of the test are best suited for making reliable taxonomic distinctions. These results suggest that both abdomen and thorax shapes represent species-specific characters. While this agrees, in part, with previous, qualitative diagnoses, our results shed light on precisely how abdomen and thorax shape differ between these species. In addition, our investigation demonstrates the taxonomic value of a morphometric approach to character analysis as thorax shape differences had gone unnoticed by previous investigators.
Financial support through SYNTHESYS funding is gratefully acknowledged; it allowed TD to visit the Natural History Museums in Berlin and in London. It was made available by the European Community–Research Infrastructure Action under the FP6–Structuring the European Research Area–Programme. We are grateful to Dave Lazarus (Berlin) for his help that allowed us to study radiolarian slides stored in the DSDP-ODP collections of the Natural History Museum in Berlin. Constructive remarks by Dave Lazarus and Takao Ubukata improved the initial manuscript.
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