Order Solemyoida Dall 1889 (clam)
Parent taxon: Protobranchia according to R. Bieler and P. M. Mikkelsen 2006
See also Coan et al. 2000, Cope 1997, Fang 2006, Mikkelsen and Bieler 2008, Nevesskaja 2009, Newell 1965, Sepkoski 2002, Spencer et al. 2004 and Vokes 1980
Sister taxa: Antactinodiontidae, Nuculaniformii, Nuculiformii, Sareptoidea, Zeehania
Subtaxa: Archaracoidea Nucinelloidea
Ecology: slow-moving infaunal chemosymbiotic