• Aaleniella variata M. A. Conti & J. C. Fischer, 1981 †: Aalenian
• Aarchaeocidaris strawberryensis Webster, 1997 †: Mississippian
• Abakana macrospina (Schoenmann, 1926) †: Givetian
• Abakaniella jangotoika Betekhtina, 1986 †: Pennsylvanian, Upper
• Abathomphalus intermedius (Bolli, 1951) †: Cretaceous, Upper
• Abathomphalus mayaroensis (Bolli, 1951) †: Cretaceous, Upper
• Abatus kieri McKinney, McNamara & Wiedman, 1988 †: Priabonian
• Abditodentrix pseudothalmanni (Boltovskoy & Guissani de Kahn, 1981): Holocene
• Abditodentrix pseudothalmanni (Boltovskoy & Guissani de Kahn, 1981): Pleistocene
• Abditodentrix pseudothalmanni (Boltovskoy & Guissani de Kahn, 1981): Pliocene
• Abditodentrix pseudothalmanni (Boltovskoy & Guissani de Kahn, 1981): Miocene
• Abdomenopora schumacheri Voigt, 1995 †: Maastrichtian
• Abelleicidaris borjnadorensis Vadet, Marignac, Nicolleau & Reboul, 2007 †: Berriasian
• Abertella gualichensis Martínez, Reichler & Mooi, 2005 †: Miocene
• Abertella kewi Durham, 1957 †: Miocene
• Abertella palmeri Durham, 1957 †: Miocene
• Abiella beloserskiensis Ivanova, 1963 †: Cisuralian
• Abiella chejagica Kanev, 1989 †: Roadian
• Abiella incerta Betekhtina, 1966 †: Guadalupian
• Abiella kolvae Kanev, 1983 †: Kungurian
• Abiella porochovskiensis Ragozin, 1938 †: Kungurian
• Abiella rotunda Ragozin, 1933 †: Cisuralian
• Abiella satura Kanev, 1994 †: Roadian
• Abiella satura Kanev, 1994 †: Kungurian
• Abiella ussovi Ragozin, 1933 †: Guadalupian
• Abiella vana Kanev, 1994 †: Wordian
• Abra cytheraeformis Cossmann & Peyrot, 1909 †: Aquitanian
• Abra deltoidea (Deshayes, 1857) †: Eocene
• Abra depressa (Deshayes, 1857) †: Eocene
• Abra deshayesi (Bosquet, 1864) †: Eocene
• Abra difficilis (Deshayes, 1857) †: Eocene
• Abra exilis (Deshayes, 1857) †: Eocene
• Abra fragosa (Marwick, 1931) †: Miocene
• Abra inflata (Laws, 1939) †: Miocene
• Abra lamberti (Deshayes, 1857) †: Eocene
• Abra macrodonta (Deshayes, 1857) †: Eocene
• Abra marshalli (H. J. Finlay, 1927) †: Miocene
• Abra media (Deshayes, 1857) †: Eocene
• Abra obtusa (Deshayes, 1857) †: Eocene
• Abra pusilla (Lamarck, 1806) †: Eocene
• Abra recluzii (Deshayes, 1857) †: Eocene
• Abra striatula (Deshayes, 1857) †: Eocene
• Abra suessoniensis (Deshayes, 1857) †: Eocene
• Abra vouastensis Périer, 1941 †: Eocene
• Absurdaster hungaricus Kroh, Lukeneder & Gallemí, 2014 †: Hauterivian
• Absurdaster meriani (Ooster, 1865) †: Cretaceous, Lower
• Absurdaster puezensis Kroh, Lukeneder & Gallemí, 2014 †: Barremian
• Absurdaster puezensis Kroh, Lukeneder & Gallemí, 2014 †: Hauterivian
• Abyssamina poagi Schnitker & Tjalsma, 1980 †: Bartonian
• Abyssamina poagi Schnitker & Tjalsma, 1980 †: Lutetian
• Abyssamina poagi Schnitker & Tjalsma, 1980 †: Ypresian
• Abyssamina quadrata Schnitker & Tjalsma, 1980 †: Bartonian
• Abyssamina quadrata Schnitker & Tjalsma, 1980 †: Lutetian
• Abyssomelania campbellae Kaim, R. G. Jenkins, Tanabe & Kiel, 2014 †: Albian
• Abyssomelania cramptoni Kaim, R. G. Jenkins, Tanabe & Kiel, 2014 †: Maastrichtian
• Abyssomelania cramptoni Kaim, R. G. Jenkins, Tanabe & Kiel, 2014 †: Campanian
• Acanomyphoria tuberosa F.-X. Guo, 1985 †: Triassic, Upper
• Acanthinula clairi Schlickum & Truc, 1972 †: Piacenzian
• Acanthinula hesslerana Jooss, 1911 †: Aquitanian
• Acanthinula karsdorfensis Kadolsky, 2020 †: Ypresian
• Acanthinula nanxiongensis W. Yu, H.-L. Gu & X.-Q. Zhang, 1990 †: Eocene
• Acanthobaktron spinosum Voigt, 1999 †: Paleocene
• Acanthocardia allae Studencka & Popov, 1996 †: Miocene
• Acanthocardia andreae (Dujardin, 1837) †: Miocene
• Acanthocardia bianconiana (Cocconi, 1873) †: Pliocene
• Acanthocardia deshayesii (Payraudeau, 1826): Calabrian
• Acanthocardia leognanensis (Mayer, 1866) †: Burdigalian
• Acanthocardia otarii (Kharatishvili, 1952) †: Miocene
• Acanthocardia perrugosa (Fontannes, 1882) †: Pliocene
• Acanthocardia saucatsensis (Mayer, 1866) †: Burdigalian
• Acanthocardia subserrigera (A. d'Orbigny, 1852) †: Burdigalian
• Acanthocardia subserrigera (A. d'Orbigny, 1852) †: Aquitanian
• Acanthocardia turonica (M. Hörnes, 1861) †: Miocene
• Acanthocardia vidali (Cossmann & Peyrot, 1912) †: Miocene
• Acanthoceramoporella brestica Pushkin, 2002 †: Ordovician
• Acanthoceramoporella granulosa (Ulrich, 1890) †: Ordovician
• Acanthoceramoporella spinigera Ernst & Munnecke, 2009 †: Hirnantian
• Acanthoceramoporella triloba (Cumings & Galloway, 1913) †: Ordovician
• Acanthoceramoporella valliensis Karklins, 1984 †: Ordovician, Upper
• Acanthochitona andegavensis Dell'Angelo, Landau, Van Dingenen & Ceulemans, 2018 †: Tortonian
• Acanthochitona chauvereauensis Dell'Angelo, Landau, Van Dingenen & Ceulemans, 2018 †: Tortonian
• Acanthochitona flebilis (Laws, 1950) †: Pliocene
• Acanthochitona globosa Dell'Angelo, Landau, Van Dingenen & Ceulemans, 2018 †: Tortonian
• Acanthochitona interglacialis Dell'Angelo, Landau, Sosso & Taviani, 2020 †: Pleistocene, Upper
• Acanthochitona mastalleri Strack, 1989: Pleistocene, Upper
• Acanthochitona penicillata (Deshayes, 1863): Pleistocene, Upper
• Acanthochitona zelandica (Quoy & Gaimard, 1835): Holocene
• Acanthochitona zelandica (Quoy & Gaimard, 1835): Pleistocene
• Acanthocidaris curvatispinis (Bell, 1892): Holocene
• Acanthocidaris curvatispinis (Bell, 1892): Cisuralian
• Acanthocidaris hastigera A. Agassiz & H.L. Clark, 1907: Holocene
• Acanthocidaris hastigera A. Agassiz & H.L. Clark, 1907: Cisuralian
• Acanthocidaris maculicollis (de Meijere, 1904): Holocene
• Acanthocidaris maculicollis (de Meijere, 1904): Cisuralian
• Acanthocladia anceps (Schlotheim, 1820) †: Permian
• Acanthocladia antiqua Nekhoroshev, 1956 †: Carboniferous
• Acanthocladia biserialis Chronic, 1949 †: Paleozoic
• Acanthocladia ciscoensis Moore, 1929 †: Pennsylvanian
• Acanthocladia crebriramosa Trizna, 1939 †: Permian
• Acanthocladia fruticosa Ulrich, 1890 †: Carboniferous