|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Craniata - Craniopsida - Craniopsidae
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.
|L. E. Popov and L. R. M. Cocks 2014||Shell dorsibiconvex, elongate oval, about 120% as long as wide, with maximum width at midlength. Both valves with hemiperipheral growth. Ventral valve weakly convex with submarginal umbo. Cicatrix area small, weakly defined. Dorsal valve lateral profile moderately convex, with maximum height at the umbonal area, steeply inclined from the umbo toward the posterior margin. Dorsal umbo submarginal with a small hemispherical protegulum. Shell surface with up to 14 regular, evenly distributed, thin growth lamellae. Ventral interior with thickened visceral area, bordered by an elevated rim (Fig. 9 O, P), about 65% as long and 50% as wide as the valve. Anterior adductor scars large, subtriangular, situated on elevated muscle platforms and bisected by a shallow groove representing an attachment track of oblique internal muscle scars. Dorsal interior with slightly thickened visceral area about 55–60% as long and 50% as wide as the valve. Anterior part of the visceral area occupied by gently impressed, slightly transverse suboval anterior adductor scars bisected by slightly elevated, strongly elongate subtriangular attachment tracks of brachial protractor muscles. Large, composite, posterior adductor and oblique internal muscle scars situated in the posterolateral parts of the dorsal visceral area. Single median scar of the levator ani recognizable in the umbonal area at posterior termination of the visceral area. Narrow, flattened limbus present along the margins of both valves.|