The infaunal descendants of the Cycloconchidae: an outline of the evolutionary history and taxonomy of the Heteroconchia, superfamilies Cycloconchacea to Chamacea

Abstract

The history of the Heteroconchia is traced from the earliest Ordovician, where they occur in shallow, marine sand and silt and inshore mud facies throughout the Palaeozoic, where in contrast to Mesozoic and more recent times they are numerically less important than the Anomalodesmata in the number of species present in the infauna. Evidence for the relationship of the heteroconch superfamilies from Cycloconchacea to Chamacea is discussed and a number of modifications to their existing classification made.