Origin and evolution of deep-sea bivalves: an hypothesis

Bathyal and abyssal faunas, both recent and fossil, seem to be characterized by the peculiar trophic structure on the bivalve assemblages, which mainly consist of deposit feeders (Paleotaxodonta) and macrophaguous carnivores (Anomalodesmata): this structure results already well established since the Cretaceous at least. The evolutionary history of different taxa as well as the peculiar characters of deep environments (stable, with a low resource supply) are the main reasons for the origin of these assemblages. The climatic deterioration during Cainozoic as well as the termohaline circulation provided new biotopes where Paleotaxodonta and Anomalodesmata settled, giving rise to many endemic new genera and species. The trophic structure could be, therefore, a useful tool in paleoecology, to identify bathyal and/or abyssal communities. -English summary