†order Billingsellida Schuchert 1893 (lamp shell)
Parent taxon: Strophomenata according to A. Williams et al. 2000
Sister taxa: Liosomeniidae, Orthotetida, Productida, Strophomenida
Subtaxa: Billingsellidina, Clitambonitidina
Ecology: stationary epifaunal suspension feeder