Acaremyidae Wood, 1949 † (extant flag source)
Acaremyidae Wood, 1949 † (basis of record)
Acrioceratidae Vermeulen, 2004 † (basis of record)
Acrioceratidae Vermeulen, 2004 † (extant flag source)
Acrocrinidae Wachsmut & Springer, 1885 † (extant flag source)
Acrocrinidae Wachsmut & Springer, 1885 † (basis of record)
Acrosmiliidae † (basis of record)
Acrosmiliidae † (extant flag source)
Acteoninidae Cossmann, 1895 † (basis of record)
Adolfiidae † (basis of record)
Adolfiidae † (extant flag source)
Aesiocrinidae † (extant flag source)
Aesiocrinidae † (basis of record)
Agatheliidae Beauvais & Beauvais, 1975 † (basis of record)
Agatheliidae Beauvais & Beauvais, 1975 † (extant flag source)
Aglaocetidae † (extant flag source)
Aglaocetidae † (basis of record)
Allodesmatidae Dall, 1895 † (basis of record)
Allodesmatidae Dall, 1895 † (extant flag source)
Angulobracchiidae Baumgartner, 1980 (basis of record)
Annuliconchidae † (extant flag source)
Annuliconchidae † (basis of record)
Anomoepodidae Lull, 1904 † (basis of record)
Anomoepodidae Lull, 1904 † (extant flag source)
Anoptychiidae Bandel, 1995 † (basis of record)
Anthracopupidae † (basis of record)
Aoujgaliaceae Termier et al., 1975 † (basis of record)
Aphrosalpingidae Myagkova, 1955 † (basis of record)
Aphrosalpingidae Myagkova, 1955 † (extant flag source)
Apographiocrinidae † (basis of record)
Apographiocrinidae † (extant flag source)
Araeoscelidae † (extant flag source)
Araeoscelidae † (basis of record)
Araripemydidae Price, 1973 † (basis of record)
Araripemydidae Price, 1973 † (extant flag source)
Archaeonycterididae Revilliod, 1917 † accepted as Archaeonycteridae † (extant flag source)
Archaeonycterididae Revilliod, 1917 † accepted as Archaeonycteridae † (basis of record)
Archaeosemantidae Kozur & Mostler, 1981 † (basis of record)
Archaeosemantidae Kozur & Mostler, 1981 † (extant flag source)
Archaeospongoprunidae Pessagno, 1973 † (extant flag source)
Archaeospongoprunidae Pessagno, 1973 † (basis of record)
Arctohedridae † (basis of record)
Arctohedridae † (extant flag source)
Asiatoceratodontidae Vorobyeva, 1967 † (basis of record)
Asiatoceratodontidae Vorobyeva, 1967 † (extant flag source)
Aulastraeoporidae Alloiteau, 1957 † (basis of record)
Aulastraeoporidae Alloiteau, 1957 † (extant flag source)
Axosmiliidae Geyer, 1955 † (extant flag source)
Axosmiliidae Geyer, 1955 † (basis of record)
Azibiidae † (basis of record)
Azibiidae † (extant flag source)
Balatonospiridae † (extant flag source)
Balatonospiridae † (basis of record)
Beckwithiidae † accepted as Aglaspididae Miller, 1877 † (extant flag source)
Beckwithiidae † accepted as Aglaspididae Miller, 1877 † (basis of record)
Beecheriidae † (basis of record)
Beecheriidae † (extant flag source)
Blothrocrinidae † (extant flag source)
Blothrocrinidae † (basis of record)
Boreiothyrididae † (basis of record)
Boreiothyrididae † (extant flag source)
Bridgerocrinidae † (extant flag source)
Bridgerocrinidae † (basis of record)
Bucanellidae Koken & Perner, 1925 † (basis of record)
Canoptidae Pessagno, 1979 † (extant flag source)
Canoptidae Pessagno, 1979 † (basis of record)
Catacrinidae † (basis of record)
Catacrinidae † (extant flag source)
Cauletellidae Caridroit, De Wever & Dumitrica, 1999 † (basis of record)
Cauletellidae Caridroit, De Wever & Dumitrica, 1999 † (extant flag source)
Cercomyidae † (extant flag source)
Cercomyidae † (basis of record)
Changshaniidae † (basis of record)
Changshaniidae † (extant flag source)
Chirotheriidae Abel, 1935 † (extant flag source)
Chirotheriidae Abel, 1935 † (basis of record)
Clistoceratidae Ruzhencev, 1975 † (basis of record)
Clistoceratidae Ruzhencev, 1975 † (extant flag source)
Clorindidae † (extant flag source)
Clorindidae † (basis of record)
Cooperinidae † (basis of record)
Cooperinidae † (extant flag source)
Coreospiridae Knight, 1952 † (basis of record)
Crassimarginatidae Frýda et al., 2002 † (basis of record)
Crassumbidae † (basis of record)
Crassumbidae † (extant flag source)
Crioceratitidae Wright, 1952 † (extant flag source)
Crioceratitidae Wright, 1952 † (basis of record)
Cryptotretidae † (basis of record)
Cryptotretidae † (extant flag source)
Cteniogenidae Seiffert, 1975 † (extant flag source)
Cteniogenidae Seiffert, 1975 † (basis of record)
Ctenodiscidae Sladen, 1889 (basis of record)
Cuniculiformidae De Wever, 1982 † (basis of record)
Cuniculiformidae De Wever, 1982 † (extant flag source)
Curtoseriidae Melnikova, 1996 † (extant flag source)
Curtoseriidae Melnikova, 1996 † (basis of record)
Cyathophoridae Vaughan & Wells, 1943 † (basis of record)
Cyathophoridae Vaughan & Wells, 1943 † (extant flag source)
Cytherissinellidae Kashevarova, 1958 † (extant flag source)