†order Protorthida Schuchert and Cooper 1931 (lamp shell)
Parent taxon: Rhynchonellata according to A. Williams et al. 2000
Sister taxa: Athyridida, Atrypida, Cadomelloidea, Cardiarinidae, Dentatrypa, Mongolellidae, Orthida, Pentamerida, Rhynchonellida, Spiriferida, Spiriferinida, Terebratulida, Thecideida, Tropidoleptidae
Subtaxa: Protorthoidea, Skenidioidea
Ecology: stationary low-level epifaunal suspension feeder