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|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Strophomenata - Strophomenida - Strophomenidae
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.
|T. W. Amsden 1974||Unequally costellate shells with rugae developed on the postero-Iateral margins only, and with strong dorsally directed geniculation. The ventral foramen is apical in position and open at maturity (pI. 21, fig. Ic), and the delthyrium is partly closed by a convex pseudodeltidium (pI. 21, fig. 1 b). The teeth are supported on welldeveloped dental plates that extend forward to enclose the subcircular muscle area; accessory plates brace the teeth (pI. 21, figs. 1 a, 1 c). The adductor muscle scars make a linear, slightly elevated track and are almost completely enclosed by the diductors (pI. 21, fig. Ic). The cardinal process has a bilobed myophore that is partly covered at its posterior end by a chilidium (pI. 21, fig. 1 h); the base of the cardinal process flares laterally to form well-developed sockets. The teeth and sockets are crenulated (pI. 21, fig. 1 q; pI. 22, fig. 1 b). Just anterior to the cardinal process shaft are two high, winglike, laterally inclined plates that converge, but do not meet, near the middle of the valve (pI. 21, fig. ie, Iq); on some specimens a median septum is also present (pI. 22, fig. Ia)|