Article: Morphology and shell microstructure of Cretaceous thecideidine brachiopods and their bearing on thecideidine phylogeny

New morphological and microstructural information from Bifolium faringdonense (Davidson, 1874), Bosquetella campichei (de Loriol, 1872), Thecidiopsis tetragona (Roemer, 1839) and Thecidiopsis bohemica imperfecta Nekvasilova, 1967 indicates that the specimens assigned to T. bohemica imperfecta do not belong to Thecidiopsis. The organization and microstructure of the brachial valve, place T. bohemica imperfecta close to thecidellinids such as the Recent Thecidellina blochmanni Dall, 1920. In comparison with other Cretaceous monoseptate forms, differences in morphology and shell microstructure clearly separate T. bohemica imperfecta, B. faringdonense and B. campichei, and are considered to be distinctive enough to allow T. bohemica imperfecta to be assigned to a new genus, Eothecidellina. The discovery of canopied brachial lobes in B. faringdonense and rudimentary canopies in the Middle Jurassic Moorellina dubia (d'Orbigny, 1850), together with the clarification of the systematic position of Eothecidellina imperfecta (Nekvasilova), provides a much clearer picture of thecidellinid evolution. The correlation of the morphology and shell microstructure of T. tetragona with basal Middle Jurassic genera and the narrowing of the thecidein plexus of descent, enables a revised thecideidine phylogeny to be presented.