Musculature of an Ordovician (Darriwilian) patelliform gastropod from Estonia

A unique internal mould of the patelliform mollusc Eesticonus aariensis n. gen. n. sp. is described from the Middle Ordovician (Darriwilian Series, Kunda Stage) of northern Estonia. Well-preserved muscle attachment scars are compared to those of Floripatella from strata of Middle Ordovician (Dapingian Series) age in Utah, originally considered to be the oldest known patelloidean gastropod but possibly an untorted mollusc. Comparison with the muscle scar pattern in Archinacellina from the Ordovician of Bohemia suggests that Eesticonus is an archinacelloidean gastropod, but not a patellogastropod.