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|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Rhynchonellata - Orthida - Plectorthidae
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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||Shell large for the genus, wider thcin long with the greatest width at about the middle; hinge narrow; cardinal extremities obtuse. Sides and anterolateral extremities broadly rounded ; anterior margin nearly straight ; anterior commissure rectimarginate to faintly uniplicate. Costellae fine, about 10 to 13 in 5 mm. at the front margin of a large adult.
Pedicle valve moderately convex in lateral profile with the maximum convexity in the median region ; anterior profile gently and broadly convex ; umbo swollen ; median region and anterior half flattened to faintly sulcate ; lateral areas gently convex ; posterolateral slopes long, moderately steep. Interarea moderately long, apsacline: Muscle field heart shaped, deeply impressed, and with a thickened anterior rim ; adductor track wide ; pallial impressions commonly exquisitely preserved.
Brachial valve strongly convex in lateral profile and with the greatest convexity slightly posterior to the middle; anterior profile strongly convex with the median region somewhat narrowly rounded; umbo swollen, sulcus narrow, shallow, extending from umbo to anterior margin ; flanks bounding sulcus swollen ; lateral and posterolateral slopes long and steep. Notothyrial cavity of moderate size; brachiophore plates somewhat reclining; median ridge short; pallial marks fairly well impressed.