Comparability of modern and ancient marine faunal provinces

In the fossil record, biogeographic data at the species level are normally not adequately preserved to be utilized in the reconstruction of marine paleoprovinces; consequently, higher taxa are employed. Thus it is cogent to question whether modern marine provinces, which are generally recognized by their species content, are still distinctive at higher taxonomic levels. Similarity coefficients computed from the bivalve and gastropod faunas of six contiguous and five spatially separated modern provinces indicate that the present-day marine provinces are in fact recognizable at the generic and in most cases at the familial level. The deficiencies and biases of the fossil record obscure the distinctiveness and reduce the precision with which ancient provinces can be delimited. Nevertheless, paleoprovinces that are recognized from the distribution patterns of genera and families are clearly comparable to modern provinces that are determined by species distributions.