COLLABORATIVE RESEARCH: Evolutionary Success in Marine Invertebrates: Testing Relationships Between Eurytopy, Longevity, and Geographic Range in Carboniferous Crinoids

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COLLABORATIVE RESEARCH: Evolutionary Success in Marine Invertebrates: Testing the Relationships between Eurytopy, Longevity, and Geographic Range in Carboniferous CrinoidsThis study will focus on the role of environmental and biogeographic factors in the evolutionary success of crinoids (echinoderms), one the most diverse and abundant groups of marine invertebrates during the Paleozoic. Lower Carboniferous (354 to 314 m.y. ago) rocks record the peak of crinoid generic diversity during their evolutionary history. Evolutionary success is measured by taxonomic longevity in the fossil record. Current understanding of reasons for evolutionary success is incomplete, but available evidence indicates a positive correlation with environmental breadth (eurytopy) and geographic range. Data supporting this correlation are limited for Paleozoic marine invertebrates. Thus, analysis of Early Carboniferous crinoids, where preliminary work supports such a correlation, will more rigorously test the correlation and broaden our understanding of the relationships between eurytopy, longevity, and geographic range in marine invertebrates. The research will compare the average stratigraphic (longevity), environmental (eurytopy), and geographic ranges of genera within crinoid groups (suborders) between North America and Europe, the two regions with the best fossil record. The study will include the Kinderhookian to early Meramecian epochs of the Mississippian Period (Early Carboniferous) of North America and the equivalent Tournaisian to middle Visean epochs of the Early Carboniferous of western Europe. Stratigraphic and geographic ranges of genera will be determined by evaluating all known species for correct generic assignment. Simultaneously, data on environmental distribution will be tabulated for genera on both continents to calculate a eurytopy index value for each genus, both intracontinental and intercontinental. Results of this investigation will bear directly on evolutionary theory as it endeavors to explain the history of life on Earth. The extensive data set derived from this study will help elucidate the roles of environment and geography in determining generic longevity and, ultimately, group longevity in defining evolutionary success.