The direct ancestor of cowries

A taxonomic revision of the extinct genus Zittelia from Jurassic sediments made it possible to trace a gradual evolutionary change in shell morphology: from the earliest species with an oval shell and elevated spire to later ones with a more globular form, in which the spire scarcely rises above the last whorl. The morphology of the aperture indicates an affinity of Zittelia with representatives of the cowries (superfamily Cypraeoidea), whose earliest members likewise appeared in the Late Jurassic.