Evolution and classification of Mesozoic mathildoid gastropods

Abstract

About 150 Mesozoic (mostly Early and Middle Jurassic) species of the heterobranch superfamily Mathildoidea are classified into four families and 27 genera. Most taxa are assigned to the families Mathildidae, Gordenellidae, and Tofanellidae while the Triassic family Anoptychiidae holds only a single genus and is restricted to the Late Triassic. Mathilda janeti is designated as type species for the genus Promathildia. Earlier designations are invalid because they refer to species which were not originally included in the genus Promathildia. As a consequence, Promathildia is transferred fromMathildidae to Gordenellidae. The generic assignment of numerous mathildoid species is changed. The suggested classification represents an arrangement which is based on shell characters; it is not based on a cladistic phylogenetic analysis.However, a great number of fossil taxa can only be classified based on shell characters. A high mathildoid diversity has been recognized from the Late Triassic Cassian Formation. Many o...