|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Rhynchonellata - Atrypida - Atrypinidae
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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.
|L.E. Popov et al. 1999||Atrypinidae with dorsibiconvex, transverse shell; ventral beak strongly curved dorsally; posterior commissure wide, broadly rounded, anterior commissure parasulcate; ventral sulcus and dorsal median fold originating at the umbonal area and sharpened by low, angular plications on flanks; radial ornament fine, equally multicostellate with accentuated median rib in ventral valve; ventral interior with hinge teeth strong; dental plates rudimentary or absent; dorsal interior with very fine median ridge and pair of oblique submedian ridges; spiralia with up to six whorls and with apices directed dorso-medially, jugum incomplete, located posteriorly.|