Ancestral morphology of crown-group molluscs revealed by a new Ordovician stem aculiferan

Abstract

Our new discovery suggests that the last common ancestor of aculiferans and conchiferans possessed a radula with numerous rows of differentiated teeth, non-biomineralised chaetae and a single calcareous shell. This body plan gave rise to the remarkable morphological diversity characteristic of the molluscan classes-a disparity that has confounded previous attempts to reconstruct the evolutionary history of the group.