|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Rhynchonellata - Atrypida - Protozygidae
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 small, elongate oval in outline with the greatest width at about the middle ; sides gently rounded ; anterior margin truncated. Surface marked by fine growth lines and the flanks by 2 to 4 obscure costae.
Pedicle valve fairly strongly convex and with the greatest convexity at about the middle ; beak elongated ; umbo narrowh/ rounded and extended anteriorly as a prominent fold to the anterior quarter where a shallow sulcus divides the fold into 2 narrowly rounded costae. Flanks concave and steep sided. Marginal fold between umbo and shoulder fairly strong.
Brachial valve with less depth and less convexity than the pedicle valve and with the maximum convexity at about the middle. Umbonal and median regions somewhat swollen. Fold narrow, originating at about two-thirds the length from the beak of the brachial valve. Flanks convex but with moderate slopes to the extremities.