BIVALVE PALEOCOMMUNITY ANALYSIS PROVIDES A CONTEXT AND COMPARATIVE FRAMEWORK FOR STUDIES OF EVOLUTIONARY PATTERNS AND PROCESSES

Bivalve paleocommunity analyses can provide invaluable evidence and crucial contextual information for understanding the patterns and processes of evolution. Paleoecological analyses of bulk fossil samples from the Jurassic of the U.S. Western Interior and Neogene of the Dominican Republic illustrate the utility of bivalves in evolutionary paleoecological studies.

Bivalve communities can serve to test evolutionary theories developed on other taxa as well as provide test cases within the clade. For example, bivalve assemblages can serve as an independent taxonomic "outgroup" with Paleozoic faunal elements and Cenozoic colonial organisms when examining patterns of persistence, turnover and evolution. Given the differences in life histories and emergent species characteristics (e.g., species longevities), the use of bivalves and bivalve community patterns can provide an independent check on the universality of evolutionary theories which were developed based on data from other taxa (e.g., coordinated stasis). In addition, since bivalves exhibit a wide range of trophic strategies (including the hosting of chemo- and photo-symbionts), tiering levels above and below the water-sediment interface, substrate preferences, mobility ability, and environmental tolerances, there are many opportunities to examine patterns of escalation, differential survival, speciation, and longevities within a diverse monophyletic group.

In Mesozoic and Cenozoic paleocommunities, bivalves are a significant faunal element as accessory organisms, as dominant organisms, and at times, as the only fossil present. And so even when evolutionary patterns are documented in non-bivalve taxa, bivalve assemblages can be used to serve as proxies for recognizing major, rapid changes in community structure and environmental conditions overlooked by large-scale sedimentological analyses. Bivalve paleocommunity analysis can provide the ecological context for understanding species-level evolution.