Building a Paleobiogeographic Atlas: A Database Approach

Biogeography is considered to be a cornerstone in the exciting, emerging study of macroecology, a field that is largely confined to investigations of the modern environment at the present time. Incomplete and inconsistent data are among the most significant challenges for paleontologists undertaking the kinds of global analyses necessary for testing and developing concepts of paleobiogeography. Such analyses require adequate sampling of globally distributed fossil assemblages and an internally consistent systematic database; the Paleobiology Database (www.paleodb.org) provides such a resource. The database presently comprises over 420,000 occurrences of fossil marine invertebrate taxa, derived from 18,000 faunal assemblages. While the database continues to increase in geographic coverage and density of sampling, considerable effort has also focused on developing a sound taxonomic framework. This resource now permits adequate analyses of spatial relationships between faunal assemblages throughout the Phanerozoic.

The purpose of this investigation is to demonstrate the utility of the database for analyzing the distribution of marine invertebrate taxa. Additionally, these data are used to quantify changes in provinciality throughout the Phanerozoic. Biogeographic units (provinces) defined by genera and subgenera of important marine invertebrate groups in the context of tectonic reconstructions are shown for nine geologic intervals across the Phanerozoic. Invertebrate groups considered are bivalves, gastropods, brachiopods, and trilobites. Cephalopods were analyzed independently to provide a contrast in biogeographic resolution between benthic and nektonic organisms. Biogeographic units were defined using consistent quantitative protocols for each time interval. The results of this preliminary analysis suggest that spatial sampling density and distribution can strongly influence perceived patterns of provinciality. In general, provinciality remains low throughout the Paleozoic and Mesozoic. After standardizing for increased geographic coverage in the Cenozoic biogeographic complexity is observed to be only slightly greater than Paleozoic-Mesozoic levels