|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Rhynchonellata - Orthida - Hesperorthidae
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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.
|D. A. T. Harper 1986||Transverse Ptychopleurella species with relatively low interarea; 13-15 costae and 14-18 costae are present on ventral and dorsal exteriors respectively, with two costae in dorsal sulcus; two costellae appear by internal branching in dorsal sulcus within 2 mm growth stage and two by external branching on either side of ventral medial rib.|