|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Strophomenata - Strophomenida - Strophomenidae
|Year||Name and author|
|1942||Dactylogonia Ulrich and Cooper|
|1956||Cyphomena Cooper pp. 840 - 841|
|2000||Dactylogonia Williams et al. p. 227|
|2002||Blyskavomena Sepkoski, Jr.|
|2002||Cyphomena Sepkoski, Jr.|
|2002||Dactylogonia Sepkoski, Jr.|
|2017||Dactylogonia Liljeroth et al.|
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|G. A. Cooper 1956 (Cyphomena)||Shell generally transversely subrectangular in outline, concavo-convex in profile; valves strongly geniculated toward the brachial valve. Surface marked by fine subequal radial costellae crossed by fine concentric lines. Costellae not grouped into zones of different sizes as in Dactylogonia. Pseudopimctate.
Pedicle valve with small but stout teeth ; thick plates extend as a rim nearly completely around the suboval muscle field. Diductor scars subcrescentic, elongate, located on each side of a short, low median ridge which divides the muscle field but is extended anteriorly for a short distance only. Incipient vascula media extend directly anteriorly from the anterior ends of the diductors. Foramen and pseudodeltidium leptaenoid.
Brachial interior with broad, shallow sockets, the inner wall of which is formed by the outer face of a broad, flat brachiophore ; notothyrial cavity filled by a thick platform which supports the cardinal process and nearly buries the brachiophore with lateral extensions. Median ridge short, extending from notothyrial platform and dividing the posterior adductors. Cardinal process formed of 2 narrow, short-shafted pieces with flat myophores. Chilidium strongly convex and covering part of the myophore surfaces. Adductor field narrowly triangular or arrow shaped in outline with the apex directed anteriorly; posterior adductors the larger, located outside the anterior pair and apparently divided into pairs by a more or less thick oblique ridge. Anterior pair elongate and separated by a short, low median ridge.