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Rhynchonellata - Orthida - Dalmanellidae
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|G. A. Cooper 1956 (Cristiferina)||Shell small, less than t inch in width, subelliptical to subcircular in outline; valves unequally convex, the brachial valve having less depth than the pedicle valve; anterior commissure gently sulcate; surface multicostellate, narrowly rounded, and strongly elevated, costellae increasing in number by intercalation. Pedicle valve with stout teeth having large fossettes; dental plates short and stout; delthyrial cavity deep; muscle area heart shaped; diductor scars protruding anterior to the ends of the dental plates and forming 2 lobes at the front of the muscle field. Traces of somewhat divergent vascula media separated by a low median ridge appear in some specimens. Brachial interior with moderately long bladelike brachiophores having short, sharp crura protruding from their inner end; brachiophores supported by strong swelling of the notothyrial platform; sockets deep; no fulcral plates; cardinal process with short, grooved shaft, expanded myophore; surface of myophore with large, recurved median plate; median ridge strongly elevated. Adductor field small.|