Musculature and asymmetry in a Carboniferous pseudo-bellerophontoidean gastropod (Mollusca)

A Single pair of well-preserved muscle attachment scars showing excellent d etail on the umbilical surface is described in a supposed bellerophontoidea n gastropod from the Carboniferous of Britain. Ontogenetic study reveals th at the bilateral symmetry of the thick-shelled adult masks an anisometric e arly growth stage, indicating that the gastropod is a pleurotomarioidean ve tigastropod masquerading as a bellerophontoidean.