Morphological Diversity of Paleozoic Pelmatozoan Echinoderms

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Several intriguing hypotheses have been proposed regarding large-scale temporal patterns of morphological diversity in the history of clades, particularly those originating in the early Paleozoic. However, the testing of evolutionary hypotheses regarding diversity has either used taxonomic diversity as a proxy for morphological diversity, or focused on patterns at relatively small scales. The proposed research will investigate temporal patterns of morphological diversity in large clades of Paleozoic echinoderms, Class Crinoidea, as well as in smaller clades. Specifically, it will be determined whether morphological diversity is concentrated early in the history of a clade, and whether there are temporally directed differences between morphological and taxonomic diversity. Morphological diversity will be measured directly, using dissimilarity measures based on discrete-character data. These data will be collected from published species descriptions as well as museum specimens. The approach adopted for quantifying morphology will allow direct documentation of morphological diversity patterns at a broader taxonomic scale than has heretofore been practiced, and will therefore provide important new data relevant to major questions of interest in evolutionary biology.