|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Rhynchonellata - Orthida - Plaesiomyidae
It was reranked as Retrorsirostra by Howe (1988), Williams et al. (2000) and Sepkoski (2002).
It was assigned to Dinorthis by Schuchert and Cooper (1932); to Plaesiomyidae by Howe (1988); to Plaesiomyinae by Williams et al. (2000); and to Orthida by Sepkoski (2002).
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.