Article: True Strophomena and a revision of the classification and evolution of strophomenoid and 'strophodontoid' brachiopods

The brachiopod superfamily Strophomenoidea is reviewed and reclassified, with chief emphasis on the form and evolution of the cardinalia, the denticulation, the ventral muscle fields, and the dorsal side sept. There are six families without denticulation along the hinge line: the Christianiidae, Foliomenida Glyptomenidae, Leptaenoideidae, Rafinesquinidae, and Strophomenidae; and seven families with denticles along the hinge line: the Amphistrophiidae, Douvillinidae, Eopholidostrophiidae, Leptostrophiida, Shaleriidae, Strophodontidae and Strophonellidae. A separate superfamily ' Strophodontacea' is not recognized since denticulation arose polyphyletically, mainly from different stocks within the Rafinesquinida. Experimentation in the development of denticles and crenulations in the Strophomenidae, Leptaeninae and other groups also occurred but was unsuccessful. The form of the cardinalia is the most important character for differentiating families apart from the later denticulate genera, in which parallel evolution of the cardinal occurred, and the form of the ventral valve muscle field and other structures are used. A lectotype is selected for Strophomena planumbona, the type species of Strophomena, and the new genus Palaeoleptostrophia is erected, with type species Stropheodonta jamesoni, from the lower Llandovery (Rhuddanian) of Girvan, Scotland. Brachyprion, Eostropheodonta, Leptaena, Rhenostrophia, and associated genera are revised, and the new family Eopholidostrophiidae is erected.