*''Aalenirhynchia''
*''Aberia''
*''Aboriginella''
*''Abrekia''
*''Absenticosta''
*''Abyssorhynchia''
*''Abyssothyris''
*''Acambona''
*''Acanthalosia''
*''Acanthambonia''
*''Acanthatia''
*''Acanthobasiliola''
*''Acanthocosta''
*''Acanthocrania''
*''Acanthoglypha''
*''Acanthoplecta''
*''Acanthoproductus''
*''Acanthorhynchia''
*''Acanthorthis''
*''Acanthospirifer''
*''Acanthospirina''
*''Acanthothyris''
*''Acanthothyropsis''
*''Acanthotoechia''
*''Acareorthis''
*''Acculina''
*''Achunoproductus''
*''Acidotocarena''
*''Acolosia''
*''Acosarina''
*''Acritosia''
*''Acrobelesia''
*''Acrobrochus''
*''Acrospirifer''
*''Acrothele''
*''Acrothyra''
*''Acrothyris''
*''Acrotreta''
*''Acrotretella''
*''Actinoconchus''
*''Actinomena''
*''Acuminothyris''
*''Acutatheca''
*''Acutella''
*''Acutilineolus''
*''Acutoria''
*''Adairia''
*''Adaptatrypa''
*''Adectorhynchus''
*''Adenus''
*''Adiaphragma''
*''Adminiculoria''
*''Admixtella''
*''Admodorugosus''
*''Adnatida''
*''Adolfia''
*''Adolfispirifer''
*''Adrenia''
*''Advenina''
*''Adygella''
*''Adygelloides''
*''Adygellopsis''
*''Aegiria''
*''Aegironites''
*''Aemula''
*''Aenigmastricklandia''
*''Aenigmastrophia''
*''Aenigmathyris''
*''Aequispiriferina''
*''Aerithyris''
*''Aerothyris''
*''Aesopomum''
*''Aetheia''
*''Aethirhynchia''
*''Afghanospirifer''
*''Afilasma''
*''Agarhyncha''
*''Agastapleura''
*''Agelesia''
*''Agerinella''
*''Agramatia''
*''Agulhasia''
*''Agyrekia''
*''Ahtiella''
*''Aidynkulirhynchia''
*''Airtonia''
*''Ajukuzella''
*''Akatchania''
*''Akelina''
*''Akopovorhynchia''
*''Aktassia''
*''Alabusherothyris''
*''Alaskospira''
*''Alatiformia''
*''Alatoproductus''
*''Alatorthotetina''
*''Aldaniopirifer''
*''Aldanotreta''
*''Aldingia''
*''Alekseevaella''
*''Alexenia''
*''Alichovia''
*''Aliconchidium''
*''Alimbella''
*''Alipunctifera''
*''Aliquantula''
*''Alisina''
*''Alispira''
*''Alispirifer''
*''Alispiriferella''
*''Alitaria''
*''Alithyris''
*''Allanella''
*''Allanetes''
*''Allorhynchoides''
*''Allorhynchus''
*''Almerarhynchia''
*''Almorhynchia''
*''Altaeorthis''
*''Altaestrophia''
*''Altaethyrella''
*''Altajella''
*''Altiplecus''
*''Altoplicatella''
*''Altunella''
*''Alvarezites''
*''Alwynia''
*''Ambardella''
*''Ambikella''
*''Ambocoelia''
*''Amboglossa''
*''Ambonorthella''
*''Ambothyris''
*''Amerista''
*''Amesopleura''
*''Ametoria''
*''Amictocracens''
*''Amissopecten''
*''Amoenirhynchia''
*''Amoenospirifer''
*''Amosina''
*''Amphiclina''
*''Amphiclinodonta''
*''Amphigenia''
*''Amphipella''
*''Amphiplecia''
*''Amphistrophia''
*''Amphistrophiella''
*''Amphithyris''
*''Amphitomella''
*''Amsdenella''
*''Amsdenina''
*''Amsdenostropiella''
*''Amurothyris''
*''Amydroptychus''
*''Amygdalocosta''
*''Anabaia''
*''Anabaria''
*''Anabolotreta''
*''Anadyrella''
*''Anakinetica''
*''Anaptychius''
*''Anarhynchia''
*''Anastrophia''
*''Anathyrella''
*''Anathyris''
*''Anatreta''
*''Anatrypa''
*''Anazyga''
*''Anchigonites''
*''Ancillotoechia''
*''Ancistrocrania''
*''Ancistrorhynchia''
*''Ancorellina''
*''Ancorhynchia''
*''Ancylostrophia''
*''Andalucinetes''
*''Andobolus''
*''Andreaspira''
*''Aneboconcha''
*''Anechophragma''
*''Anelotreta''
*''Anemonaria''
*''Angarella''
*''Angiospirifer''
*''Angulotreta''
*''Angusticardinia''
*''Angustothyris''
*''Aniabrochus''
*''Anidanthus''
*''Animonithyris''
*''Anisactinella''
*''Anisopleurella''
*''Annuloplatidia''
*''Anomactinella''
*''Anomalesia''
*''Anomaloglossa''
*''Anomaloria''
*''Anomalorthis''
*''Anoplia''
*''Anopliopsis''
*''Anoplotheca''
*''Anoptambonites''
*''Ansehia''
*''Antelocoelia''
*''Anteridocus''
*''Antezeilleria''
*''Anthracospirifer''
*''Antigonambonites''
*''Antigoniarcula''
*''Antinomia''
*''Antiptychina''
*''Antiquatonia''
*''Antirhynchonella''
*''Antispirifer''
*''Antistrix''
*''Antistrixia''
*''Antizygospira''
*''Antronaria''
*''Anulatrypa''
*''Anx''
*''Aorhynchia''
*''Aparimarhynchia''
*''Apatecosia''
*''Apatobolus''
*''Apatomorpha''
*''Apatorthis''
*''Apatoskenidioides''
*''Aperispirifer''
*''Apertirhynchella''
*''Aphanomena''
*''Aphaurosia''
*''Apheathyris''
*''Aphelesia''
*''Aphelotreta''
*''Apheoorthina''
*''Apheoorthis''
*''Aphragmus''
*''Apicilirella''
*''Apletosia''
*''Apodosia''
*''Apollonorthis''
*''Apomatella''
*''Apopentamerus''
*''Aporthophyla''
*''Aporthophylina''
*''Apothyris''
*''Apousiella''
*''Apringia''
*''Apsilingula''
*''Apsocalymma''
*''Apsotreta''
*''Arabatia''
*''Arabicella''
*''Araksalosia''
*''Araneatrypa''
*''Arapsopleurum''
*''Araspirifer''
*''Aratanea''
*''Aratella''
*''Aratoechia''
*''Araxathyris''
*''Araxilevis''
*''Arbizustrophia''
*''Arcelinithyris''
*''Arceythyris''
*''Archaeorthis''
*''Archaiosteges''
*''Archeochonetes''
*''Arcosarina''
*''Arcticalosia''
*''Arctireta''
*''Arctispira''
*''Arctochonetes''
*''Arctohedra''
*''Arctomeristina''
*''Arctosia''
*''Arctothyris''
*''Arcualla''
*''Arcuatothyris''
*''Arcullina''
*''Ardiviscus''
*''Ardmosteges''
*''Arduspirifer''
*''Areella''
*''Arenaciarcula''
*''Arenorthis''
*''Areostrophia''
*''Argella''
*''Argentiproductus''
*''Argorhynx''
*''Argovithyris''
*''Argyrotheca''
*''Arionthia''
*''Arktikina''
*''Aromasithyris''
*''Articalosia''
*''Artimyctella''
*''Artiotreta''
*''Artospirifer''
*''Aseptagypa''
*''Aseptalium''
*''Aseptella''
*''Aseptirhynchia''
*''Aseptonetes''
*''Asiarhynchia''
*''Asioproductus''
*''Askepasma''
*''Asperlinus''
*''Aspidothyris''
*''Aspinosella''
*''Astaristrophia''
*''Astegosia''
*''Astraborthis''
*''Astua''
*''Asturorthis''
*''Astutorhyncha''
*''Asymmetrochonetes''
*''Asymphylotoechia''
*''Asyrinx''
*''Asyrinxia''
*''Atactosia''
*''Atelelasma''
*''Atelelasmoidea''
*''Atelestegastus''
*''Atelithyris''
*''Athabaschia''
*''Athyrhynchus''
*''Athyris''
*''Athyrisina''
*''Athyrisinoides''
*''Athyrisinopsis''
*''Athyrorhynchia''
*''Atlanticocoelia''
*''Atlantida''
*''Atribonium''
*''Atrypa''
*''Atryparia''
*''Atrypella''
*''Atrypellina''
*''Atrypina''
*''Atrypinella''
*''Atrypinopsis''
*''Atrypoidea''
*''Atrypopsis''
*''Atrypunculus''
*''Atrythyris''
*''Attenuatella''
*''Auchmerella''
*''Aucklandirhynchia''
*''Aulacatrypa''
*''Aulacella''
*''Aulacorphora''
*''Aulacothyris''
*''Aulacothyroides''
*''Aulacothyropsis''
*''Aulidospira''
*''Aulie''
*''Aulites''
*''Aulonotreta''
*''Auloprotonia''
*''Aulosteges''
*''Auricolispina''
*''Austinella''
*''Australiarcula''
*''Australina''
*''Australirhynchia''
*''Australispira''
*''Australocoelia''
*''Australosia''
*''Australospirifer''
*''Australostrophia''
*''Austriellula''
*''Austrirhynchia''
*''Austrochoristites''
*''Austrohedra''
*''Austronoplia''
*''Austrospirifer''
*''Austrothyris''
*''Avisyrinx''
*''Avonia''
*''Avonothyris''
*''Axiodeaneia''
*''Azamella''
*''Azygidium''