|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Rhynchonellata - Orthida - Harknessellidae
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.
|B. G. Baarli 1988||Shell biconvex and subcircular with relatively short hinge line. Ribbing costellate and costellae situated in posterior portion of shell recurving posteriorly to intersect posterior valve margin. Small ventral umbo. Ventral muscle scars widely cordate with diductor lobes extending|