NON-SELECTIVITY IN EXTINCTION OF BIVALVES IN THE LATE CRETACEOUS OF THE ATLANTIC AND GULF COASTAL-PLAIN OF NORTH-AMERICA

It has been suggested that the biogeographic and clade-level character istics of marine invertebrate groups important in survival through mas s extinctions are different from those important in survival during no rmal times. The role played by ecologically important characters in su rvival across mass extinctions, however, has not been well-studied. We obtained information from the literature about the feeding mode and m orphology, burrowing habits, size and depth below sea-level inhabited, temperature range, shell thickness, species richness and abundance of bivalve genera present in the Late Cretaceous of the Atlantic and Gul f Coastal Plain of North America. Non-parametric analysis revealed tha t there were no significant associations between any of these characte ristics and survival across the Cretaceous-Tertiary boundary. This lac k of selectivity may be due to varying local conditions, which favor d ifferent ecological characteristics in each area and produce no overal l pattern of selectivity. It might also be indicative of the severity of this extinction on bivalves - differences in ecological habits may have been virtually irrelevant to survivorship through this event.