CONODONTS THROUGH TIME AND SPACE: STUDIES IN CONODONT PROVINCIALISM.

摘要

A computerized file of approximately twenty thousand records of conodont occurrences was used in a quantitative study of conodont provincialism. Although biases in the fossil record, in specimen collection, and in data collection preclude any rigid statistical testing, study of quantitative measures of similarity between faunas, when combined with paleogeographic reconstructions, can given insight into provincial patterns and their possible causes.; Conodonts showed strong provinciality three times during the Paleozoic. In each instance, temperature is a plausible control of the provincial distribution. In the Ordovician, one fauna inhabited the low to mid latitudes in Laurentia, China, Siberia, and northern Gondwana. Another fauna inhabited high latitudes in Baltica. Cooler high-latitude temperatures as compared to warmer low-latitude temperatures could have been the factor controlling distrubition. In the Early Devonian, the Aurelian-province fauna (in present-day Europe and Turkey) inhabited a semi-restricted seaway while the Tasman-Cordilleran-province fauna (in present-day western North America, Siberia, and Australia) occupied the shores of a larger ocean. Eastern North America had a seemingly transitional fauna. These provinces were all in low to mid latitudes but reconstructed current patterns suggest a warmer temperature in the Aurelian seaway than in the larger ocean. In the Pennsylvanian and Permian, the fauna in western Pangaea (present-day North America) differed from that in eastern Pangaea (present-day Eurasia). Again both provinces were in low to mid latitudes, but a stronger westward equatorial current due to the Pennsylvanian-Permian glacial episode could have contributed to a warming of the eastern (Tethyan) coast relative to the western coast.