|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||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.
|P. Copper 1986||Small, ventribiconvex to biconvex. sometimes weakly ventrocarinate shells with smooth umbonal regions. smooth or corrugated anterior and lateral commissure, weakly sulcate. Small anacline to hypercline beak. Internally thin shelled. small dental cavities. Minute deltidial plates. delicate medially dim:u:d teeth; thin socket plates. laterally pointed crum curving dorsally into ascending lamellae. in turn giving rise anteriorly to a dorsal complete or incomplete jugum and ventrally into a revolution of one whorl or less. Median dorsal septum absent or faint.|