Ac
†Acallosuchus Long and Murry 1995
- †Acallosuchus rectori Long and Murry 1995
Reptilia → Eosuchia → Neodiapsida
- Acerodontosauridae †
†Porodica Acerosodontosauridae
- Acerosodontosaurus,
- Aciprion,
- Acrodonta,
Ad
†Adelosaurus Watson 1914
- †Adelosaurus huxleyi Hancock and Howse 1870
Ae
- Aegyptosuchidae †
- Aegyptosuchus †
- Aeolodon †
- Aetosauria Lydekker, 1889 †
- Aetosauridae,
- Aetosaurus
Af
- Afairiguana,
Ag
- Agama,
- Agamidae,
- Agaminae,
- Agkistrognathus Nicholls & Brinkman, 1993 †
- Agrestipus,
Ai
- Aigialosuchus †
Ak
- Akropus,
Al
- Alligator Cuvier, 1807
- Alligatorellus †
- Alligatoridae
- Alligatorium †
- Allodaposuchus Nopcsa, 1928 †
- Allognathosuchus †
Am
- Ammorhynchus,
- Amphisbaena,
- Amphisbaenia,
- Amphisbaeniformes,
- Amphisbaenoidea,
An
- Anarosauridae,
- Anarosaurus Dames, 1890 †
- Anchaurosaurus,
- Angistorhinopsis,
- Angistorhinus,
- Anglosuchus †
- Angustinaripterus He, Yan & Su, 1983 †
- Anhanguera Campos & Kellner, 1985 †
- Anhangueridae Campos & Kellner, 1985 †
- Anhanguerinae †
- Anisodontosaurus,
- Anisolepinae,
- Ankistrodon indicus,
- Anniealexandria,
- Anolis,
- Anomalopsis,
- Anomosaurus,
- Anquingosaurus,
- Anshunsaurus Liu, 1999 †
- Antipus,
- Anurognathidae Kuhn, 1937 †
- Anurognathus Doederline, 1923 †
Ap
- Apatopodidae,
- Apatopus,
- Aphrosaurus Welles, 1943 †
- Aptychodon,
Ar
- Araeoscelida †
- Araeoscelidae †
- Araeoscelidae,
- Araeoscelidia,
- Araeoscelis,
- Araeosceloidea,
- Arambourgia †
- Arambourgiania Nesov & Borkin, 1989 †
- Araripedactylus Wellnhofer, 1977 †
- Araripesaurus Price, 1971 †
- Araripesuchus †
- Archaeonectrus Novozhilov, 1964 †
- Archaeosuchia †
- Archaerhineura,
- Archeopelta,
- Archosauria
- Archosauria,
Klada Archosauriformes Gauthier 1986 †
- †Arctosaurus Adams 1875
- †Asperoris Nesbitt et al. 2013
- †Barberenasuchus Mattar 1987
- †Collilongus Borsuk−Białynicka and Sennikov 2009
- †Crosbysaurus Heckert 2004
- †Crurotarsi Sereno and Arcucci 1990
- †Doswelliidae Weems 1980
- †Dyoplax Fraas 1867
- †Eorasaurus Sennikov 1997
- †Erythrosuchia Bonaparte 1984
- †Erythrosuchidae Watson 1917
- †Euparkeriidae Huene 1920
- †Graoullyodon Godefroit and Cuny 1997
- †Koilamasuchus Ezcurra et al. 2010
- †Lucianosaurus Hunt and Lucas 1993
- †Plateosaurus ornatus Huene 1905
- †Protecovasaurus Heckert 2004
- †Proterochampsia Kischlat 2000
- †Proterosuchidae Broom 1906
- †Tecovasaurus Hunt and Lucas 1994
- †Uatchitodon Sues 1991
- †Vancleavea Long and Murry 1995
- †Wangisuchus Young 1964
- †Wangisuchus tzeyii Young 1964
- †Zanclodon Plieninger 1846
Reptilia → Diapsida → Archosauromorpha
Infrarazred Archosauromorpha Huene 1946
- †Archosauriformes Gauthier 1986
- †Azendohsaurus Dutuit 1972
- †Czatkowiella Borsuk−Białynicka and Evans 2009
- †Drepanosauridae Berman and Reisz 1992
- †Gwyneddosaurus Bock 1945
- †Mecistotrachelos Fraser et al. 2007
- †Megalancosauridae Olshevsky 1991
- †Noteosuchus Broom 1925
- †Prolacertiformes Camp 1945
- †Protorosauria Huxley 1871
- †Rhabdopelix longispinis Cope 1866
- †Rhynchosauria Osborn 1903
- †Teraterpetidae Sues 2003
- †Trilophosauria Romer, 1956
- †Trilophosauridae Gregory 1945
Reptilia → Eureptilia → Romeriida → Diapsida
- Archosaurus,
- Arctosaurus,
- Ardeosauridae,
- Ardeosaurus,
- Aristelliger,
- Aristonectes Cabrera, 1941 †
- Armadillosuchus Marinho & Carvalho, 2009 †
- Arretosauridae,
- Arretosaurus
- Arthurdactylus Frey & Martill, 1994 †
As
- Asiatosuchus †
- Asilisaurus,
- Askeptosauridae Kuhn-Schnyder, 1952 †
- Askeptosauroidea,
- Askeptosaurus Nopcsa, 1925 †
- Asperoris,
At
- Atopodentatus,
- Atoposauridae †
- Atoposaurus †
- Atreipus,
- Attenborosaurus Bakker, 1993 †
Au
- Augustasaurus Sander, Rieppel & Bucher, 1997 †
- Austriadactylus Dalla Vecchia, Wild, Hopf & Reitner, 2002 †
- Austriadactylus,
Av
- Avalonianus,
Klada †Avemetatarsalia Benton 1999
- †Ornithodira Gauthier 1986
- †Scleromochlidae Huene 1914
Diapsida → Archosauromorpha → Archosauriformes → Crurotarsi → Archosauria
†Klada Avicephala Senter 2004
- †Coelurosauravus Piveteau 1926
- †Longisquama Sharov 1970
- †Simiosauria Senter 2004
- Avipes,
Az
Azendohsaurus Dutuit 1972
- †Azendohsaurus laaroussii Dutuit 1972
- †Azendohsaurus madagaskarensis Flynn et al. 2010