Stratigraphic time - taxa
genus Aberrokorynetes Winkler, 1990 (Priabonian)
species Aberrokorynetes abludens Winkler, 1990 (Priabonian)
species Aberrokorynetes oceanojubilaei Kolibáč, Alekseev, Kairišs & Bukejs, 2021 (Priabonian)
genus Abies Mill. - fir (Hauterivian - recent)
species Abies cuprovallis Axelrod (Eocene)
species Abies deweyensis Ting (Eocene)
species Abies sibiriciformis Zaklinskay, 1957 (Eocene)
subfamily Abietoideae Lindl. Emend Pilger & Melchior (Hauterivian - recent)
genus Abyssothyris Thomson, 1927 (Tertiary - recent)
species Acaenitus defunctus (Brues, 1906) (Eocene)
legio Acalyptratae Macquart, 1835 (Upper Eocene - recent)
species Acanthechinus peloria (Clark in Arnold & Clark, 1927) (Eocene)
infraorder Achelata Scholtz & Richter, 1995 (Lower Triassic - recent)
suborder Acipenseroidei (Upper Cretaceous - recent)
genus Aclistomycter Wilson, 1971 (Upper Eocene)
species Aclistomycter middletoni Wilson, 1971 (Upper Eocene)
genus Acrobrochus Cooper, 1983 (Tertiary - recent)
superorder Actinistia (Middle Devonian - recent)
class Actinopterygii Klein, 1885 - ray-finned fishes (Upper Silurian - recent)
genus Adamsochrysa Makarkin & Archibald, 2013 (Eocene)
suborder Adephaga Schellenberg, 1806 (Hettangian - recent)
genus Aegyptocetus Bianucci & Gingerich, 2011 (Upper Eocene)
species Aegyptocetus tarfa Bianucci & Gingerich, 2011 (Upper Eocene)
subfamily Aesalinae MacLeay, 1819 (Cenomanian - recent)
tribus Aesalini MacLeay, 1819 (Upper Cretaceous - recent)
family Agamidae Gray, 1827 - agamas (Upper Cretaceous - recent)
species Agriochoerus antiquus Leidy, 1850 (Upper Eocene)
species Agriochoerus maximus Douglass, 1901 (Upper Eocene)
subfamily Agrypninae Candèze, 1857 (Cenomanian - recent)
genus Alavesia Waters & Arillo, 1999 (Cenomanian - recent)
subfamily Aleuropteryginae (Callovian - recent)
genus Alicodoxa Emeljanov & Shcherbakov, 2011 (Priabonian)
species Alicodoxa rasnitsyni Emeljanov & Shcherbakov, 2011 (Priabonian)
subtribus Alleculina Seidlitz, 1836 (Priabonian - recent)
family Alligatoridae Gray, 1844 (Upper Cretaceous - recent)
genus Amartus LeConte, 1861 (Priabonian - recent)
species Amartus petrefactus Wickham, 1912 (Priabonian)
tribus Amarygmini Gistel, 1848 (Priabonian - recent)
genus Amblyteles Wesmael, 1844 (Priabonian - recent)
species Amblyteles pealei Cockerell, 1927 (Priabonian)
order Ambystomatoidea (Upper Cretaceous - recent)
family Amiidae Bonaparte, 1831 - bowfins (Upper Jurassic - recent)
order Amiiformes Hay, 1929 - bowfins (Lower Triassic - recent)
subfamily Amnestinae Hart, 1919 (Aptian - recent)
kingdom Amoebozoa Lühe, 1913 emend. Cavalier-Smith, 1998 (Neoproterozoic - recent)
family Amorphoscelidae Stål, 1877 (Aptian - recent)
subfamily Amorphoscelinae Stål, 1877 (Aptian - recent)
tribus Amorphoscelini Stål, 1877 (Aptian - recent)
family Amphisbaenidae Gray, 1865 - worm lizards (Upper Eocene - recent)
family Amphiumidae Garden in Smith, 1821 - amphiumas (Upper Cretaceous - recent)
order Amphiumoidea (Upper Cretaceous - recent)
subfamily Anaidinae Nikolajev, 1996 (Lower Cretaceous - recent)
species Ancyrona eocenica Schmied, Wappler & Kolibác, 2009 (Eocene)
tribus Ancyronini Kolibáč, 2006 (Eocene - recent)
family Anguidae Gray, 1825 - glass lizards (Upper Cretaceous - recent)
family Aniliidae Stejneger, 1907 - cylinder snakes (Cretaceous - recent)
species Anisaster gibberulus (Cotteau, 1847) (Eocene)
suborder Anisoneura Lioy, 1864 (Upper Triassic - recent)
infraorder Anisopodomorpha Tuomikoski, 1961 (Upper Triassic - recent)
genus Antephilorhizus Kirichenko-Babko, 2021 (Priabonian)
species Antephilorhizus pripiatiensis Kirichenko-Babko & Perkovsky, 2021 (Priabonian)
species Antephilorhizus zerovae Kirichenko-Babko & Perkovsky, 2022 (Priabonian)
family Anthribidae Billberg, 1820 - fungus weevils (Middle Jurassic - recent)
subfamily Anthribinae Billberg, 1820 (Lower Eocene - recent)
suborder Apocrita Gerstäcker, 1867 (Berriasian - recent)
infraclass Apoda Oppel, 1810 (Lower Jurassic - recent)
family Aradidae Brullé, 1836 (Cenomanian - recent)
superfamily Aradoidea Brullé, 1836 (Cenomanian - recent)
family Araucariaceae Henkel & Hochst. (Oxfordian - recent)
family Arbaciidae Gray, 1855 (Lower Cretaceous - recent)
species Archaeotragulus krabiensis Métais, Chaimanee, Jaeger & Ducrocq, 2001 (Upper Eocene - Chattian)
genus Archiconiocompsa Enderlein, 1910 (Priabonian)
genus Archiconis Enderlein, 1930 (Priabonian)
genus Archiraphidia Handlirsch, 1910 (Priabonian)
species Archiraphidia somnolenta (Scudder, 1890) (Priabonian)
species Archiraphidia tranquilla (Scudder, 1890) (Priabonian)
species Archiraphidia tumulata (Scudder, 1890) (Priabonian)
superorder Archosauria (Lopingian - recent)
cohors Archosauromorpha Huene, 1946 (Lopingian - recent)
suborder Archostemata Kolbe, 1908 (Upper Triassic - recent)
family Arretosauridae Gilmore, 1943 (Upper Eocene)
family Artematopodidae Lacordaire, 1857 (Upper Eocene - recent)
phylum Arthropoda Gravenhorst, 1843 - arthropods (Cambrian - recent)
order Artiodactyla Owen, 1841 - even-toed ungulates (Lower Eocene - recent)
tribus Asclerini Gistel, 1848 (Upper Eocene - recent)