Order Unionida Stoliczka 1871 (clam)
Alternative spelling: Unionoida
Parent taxon: Palaeoheterodonta according to R. Bieler et al. 2014
See also Beu et al. 1990, Bieler and Mikkelsen 2006, Bouchet et al. 2010, Carter et al. 2011, Giribet and Wheeler 2002, Nevesskaja 2009, Newell 1965, Sepkoski 2002, Shoshani et al. 1989 and Vokes 1980
Sister taxa: Trigoniida, Unioni, Thoraliidae
Subtaxa: Actinodontophoroidea Amblemidae Archanodontacea Archanodontoidea Carydioidea Etherioidea Hyriidina Protelliptio Silesunionidina Silesunionina Tihkia Unionidina
Ecology: facultatively mobile infaunal suspension feeder