|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).