The extinct Nerineoidea and Acteonelloidea (Heterobranchia, Gastropoda): a palaeobiological approach

Abstract

ABSTRACT Based on the morphology of the aperture and internal plaits or folds, the Nerineoidea Zittel, 1873 are subdivided into seven families: the Pseudonerineidae Pchelintsev, 1965, Ceritellidae Wenz, 1940, Nerinellidae Pchelintsev, 1960, Eunerineidae n. fam. (new family that includes the Nerineidae Zittel, 1873 (pars) and the Diptyxidae Bouchet & Rocroi, 2005) the Ptygmatididae Pchelintsev, 1960, Nerineidae and Itieriidae Cossmann, 1896. The internal plaits of the Nerineoidea had different functions: the columellar plaits subdivided the columellar muscle into strands, which allowed portions of the foot to be moved individually. A tubelike space delimited by the parietal and palatal plaits is compared with the pallial caecum or posterior mantle chamber of heterobranchs and served the respiration. Waste from both mantle chambers was expelled through a subsutural notch, which is the common feature of the Nerineoidea. The Nerineoidea were shell draggers and probably deposit feeders with a semi- infaunal mo...