Acanthalosia Waterhouse, 1986 † (basis of record)
Acanthocrania Williams, 1943 † (basis of record)
Acanthothirididae Schuchert, 1913 † (basis of record)
Acrosaccus Willard, 1928 † (basis of record)
Acrospiriferidae Termier & Termier, 1949 † (additional source)
Acrothelidae Schuchert, 1893 † (basis of record)
Acrotheloidea Walcott, 1908 † (basis of record)
Acrotreta Kutorga, 1848 † (basis of record)
Acrotretella Ireland, 1961 † (basis of record)
Acrotretida † (additional source)
Acrotretidae Schuchert, 1893 † (basis of record)
Acrotretoidea Schuchert, 1893 † (additional source)
Adensuidae Popov & Rukavishnikova, 1986 † (basis of record)
Adnatidinae Williams et al., 2006 † (original description)
Adolfiidae Sartenaer, 1966 † (basis of record)
Adolfioidea Sartenaer, 1966 † (basis of record)
Aemula Steinich, 1968 † (basis of record)
Aenigmastrophiidae Boucot & Rong, 1994 † (basis of record)
Aetheia Thomson, 1915 † (additional source)
Aetheiinae Cooper, 1959 † (additional source)
Agulhasiinae Muir-Wood, 1965 † (additional source)
Alabushevothyrididae Smirnova, 1994 † (basis of record)
Alabushevothyris Smirnova, 1994 † (additional source)
Aldingia Thomson, 1916 (additional source)
Alisina Rowell, 1962 † (additional source)
Allorhynchidae Cooper & Grant, 1976 † (additional source)
Almorhynchia Ovtsharenko, 1983 † (basis of record)
Ambocoeliidae George, 1931 † (basis of record)
Ambocoeliinae George, 1931 † (basis of record)
Ambocoelioidea George, 1931 † (basis of record)
Amphipellidae Cooper & Grant, 1976 † (additional source)
Amphistrophiidae Harper, 1973 † (basis of record)
Anazygidae Davidson, 1883 † (basis of record)
Anazygidina † (basis of record)
Anazyginae Davidson, 1883 † (basis of record)
Anazygoidea Davidson, 1883 † (basis of record)
Ancistrorhynchidae Cooper, 1956 † (basis of record)
Ancistrorhynchoidea Cooper, 1956 † (basis of record)
Aniabrochinae Mancenido, 1993 † (basis of record)
Anoplothecidae Schuchert, 1894 † (basis of record)
Anoplothecoidea Schuchert, 1894 † (basis of record)
Aperispirifer Waterhouse, 1968 † (taxonomy source)
Aphelesiinae Cooper, 1959 † (additional source)
Apringia Gregorio, 1886 † (basis of record)
Archboldina Waterhouse, 2001 † (additional source)
Arcticalosia Waterhouse, 1986 † (additional source)
Arctitreta Whitfield, 1908 † (basis of record)
Artiotreta Ireland, 1961 † (basis of record)
Aseptorhynchiidae Savage, 1996 † (basis of record)
Atelithyris Smirnova, 1975 † (basis of record)
Athyridida † (basis of record)
Athyrididae Davidson, 1881 † (additional source)
Athyrididina † (basis of record)
Athyridoidea Davidson, 1881 † (basis of record)
Athyrisininae Grabau, 1931 † (additional source)
Atriboniidae Grant, 1965 † (basis of record)
Atrypa Dalman, 1828 † (basis of record)
Atrypida † (basis of record)
Atrypidae Gill, 1871 † (basis of record)
Atrypidina † (basis of record)
Atrypinae Gill, 1871 † (basis of record)
Atrypinidae McEwan, 1939 † (basis of record)
Atrypoidea Gill, 1871 † (basis of record)
Aulonotretidae Williams et al., 2000 † (original description)
Auloprotonia Muir-Wood & Cooper, 1960 † (basis of record)
Aulostegidae Muir-Wood & Cooper, 1960 † (basis of record)
Aulosteginae Muir-Wood & Cooper, 1960 † (basis of record)
Aulostegoidea Muir-Wood & Cooper, 1960 † (basis of record)
Auriculispininae Waterhouse, 1986 † (basis of record)
Australiarcula Elliott, 1960 † (taxonomy source)
Austrirhynchidae Ager, 1959 † (basis of record)
Babukellinae MacKinnon, Smirnova & Lee, 2002 (original description)
Bactryniidae Williams, 1965 † (basis of record)
Balatonospiridae Dagys, 1974 † (basis of record)
Bandoproductus Jing & Sun, 1981 † (additional source)
Basiliolella d'Hondt, 1987 (additional source)
Biernatiidae Holmer, 1989 † (basis of record)
Billingsellida † (basis of record)
Billingsellidina † (additional source)
Bittnerulidae Schuchert, 1929 † (basis of record)
Boreiothyrididae Dagys, 1968 † (basis of record)
Botsfordiidae Schindewolf, 1955 † (basis of record)
Bouchardiella Doello-Jurado, 1922 † (additional source)
Brachythyrididae Fredericks, 1924 † (basis of record)
Brachythyridoidea Frederiks, 1924 † (basis of record)
Buxtoniinae Muir-Wood & Cooper, 1960 † (basis of record)
Callytharrella Archbold, 1985 † (additional source)
Camarotoechioidea Schuchert, 1929 † (basis of record)
Camerellidae Hall & Clarke, 1894 † (basis of record)
Camerelloidea Hall & Clarke, 1894 † (basis of record)
Camerophorinidae Rzhonsnitskaia, 1958 † (basis of record)
Capillithyrididae Cooper, 1983 † (additional source)
Capillithyridinae Cooper, 1983 † (additional source)
Carinatinidae Rzhonsnitskaya, 1960 † (basis of record)
Ceratretidae Rowell, 1965 † (basis of record)
Chathamithyris Allan, 1932 † (taxonomy source)
Cheirothyropsidae Cooper, 1983 † (additional source)
Cheniothyrididae Muir-Wood, 1965 † (basis of record)
Chileata † (basis of record)
Chileida † (basis of record)