†order Sulcavitida Qian 1989 (mollusk)
Parent taxon: Hyolithomorpha according to P. D. Kruse 2002
Sister taxa: Calcitheca, Dilites, Eumorpholites, Nervolites, Ovalitheca, Parahyolithes, Toxeumorphorida
Subtaxa: Cardiolithidae, Dorsojugatidae, Gakidae, Inflatatheca, Inflaticornidae, Linevitidae, Parakorilithidae, Trapezovitidae
Ecology: stationary epifaunal suspension feeder