NEW DATA ON THE MORPHOLOGY OF ANCIENT GASTROPODS OF THE GENUS ALDANELLA VOSTOKOVA, 1962 (ARCHAEOBRANCHIA, PELAGIELLIFORMES)

Abstract

The position of attachment of the shell muscle is discovered in the columellar area of the shell of the Early Cambrian univalved genus Aldanella (family Aldanellidae, order Pelagielliformes, subclass Archaeobranchia), the structure of its protoconch is described, and the presence of series of septa in the embryonic part of their shell is confirmed. These new features confidently support the position of the family Aldanellidae within the gastropod class and allow them to be considered ancestral to younger gastropod lineages with a turbospiral shell. © Pleiades Publishing, Inc. 2006.