Order Trigoniida Dall 1889
Alternative spelling: Trigonioida
Parent taxon: Unionata according to J. G. Carter et al. 2011
See also Bieler and Mikkelsen 2006, Bouchet et al. 2010, Giribet and Wheeler 2002, Newell 1965, Scholz et al. 2008, Sepkoski 2002 and Vokes 1980
Sister taxon: Unionida
Subtaxa: Andivaugonia Antutitrigonia Arabitrigonia Beichuanioidea Columbitrigonia Dampietrigonia Gobiella Heslingtonia Kupenga Litotrigonia Lyrodesmatacea Macrotrigonia Mediterraneotrigonia Megatrigonioidea Myophorellina Myophorelloidea Nakanotrigonia Neuquenenitrigonia Paranditrigonia Procostaria Pseudocardinioidea Skwarkoella Trigoniina Trigonioidea Trigonioidoidea Trigonodoidea Virgotrigonia Zaletrigonia Zulutrigonia