This list of the Cenozoic life of Colorado contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Colorado and are between 66 million and 10,000 years of age.

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Abies †Abies longirostris †Absarokius †Absarokius abbotti – or unidentified comparable form †Absarokius metoecus †Absyrtus †Absyrtus decrepitus – type locality for species †Acaenitus †Acaenitus defunctus – type locality for species †Acalles †Acalles exhumatus – type locality for species †Acallomyia †Acallomyia probolaea – type locality for species †Acalyptus †Acalyptus obtusus – type locality for species †Acanthomyites – type locality for genus †Acanthomyites aldrichi – type locality for species †Acarictis – or unidentified comparable form †Acarictis ryani Acer †Acer florissanti †Acer fragile †Acer macginitiei †Acer oregonianum †Achrestocoris – type locality for genus †Achrestocoris cinerarius – type locality for species †Acilius †Acilius florissantensis – type locality for species †Aciprion – type locality for genus †Aciprion formosum – type locality for species †Aciprion majus – type locality for species †Acnemia †Acnemia cyclosoma – type locality for species †Acocephalus †Acocephalus callosus – type locality for species Acris †Acritoparamys †Acritoparamys atwateri †Acritoparamys pattersoni Acrostichum †Acrostichum hesperium †Acylophorus †Acylophorus immotus – type locality for species †Adalia †Adalia subversa – type locality for species †Adelocera †Adelocera perantiqua – type locality for species †Adelopsyche – type locality for genus †Adelopsyche frustrans – type locality for species †Adjidaumo †Adjidaumo minimus †Adjidaumo minutus †Adocus Aegialia †Aegialia opaca †Aelurodon †Aelurodon asthenostylus †Aepycamelus †Aepycamelus giraffinus Aeshna †Aeshna larvata – type locality for species †Aeshna solida – type locality for species Agabus †Agabus charon – type locality for species †Agabus florissantensis – type locality for species †Agabus infuscatus †Agabus rathbuni – type locality for species †Agallia †Agallia abstructa – type locality for species †Agallia flaccida – type locality for species †Agallia instabilis – type locality for species †Agallia lewisii – type locality for species †Agathemera †Agathemera reclusa – type locality for species Agelaius †Agelaius phoenicieus †Agenia †Agenia cockerellae – type locality for species †Agenia saxigena – type locality for species †Agnotocastor †Agnotocastor coloradensis – type locality for species Agoliinus †Agoliinus plutonicus Agrilus †Agrilus liragus †Agrilus praepolitus – type locality for species †Agrion †Agrion exsularis – type locality for species †Agrion mascescens – type locality for species †Agrion telluris – type locality for species Agriotes †Agriotes apicalis †Agriotes comminutus – type locality for species †Agriotes nearcticus – type locality for species †Agromyza †Agromyza praecursor – type locality for species †Agulla †Agulla protomaculata – type locality for species †Agyrtes †Agyrtes primoticus – type locality for species †Ailanthus †Ailanthus americana †Ailanthus lesquereuxi †Aleocharopsis †Aleocharopsis caseyi – type locality for species †Aleocharopsis secunda – type locality for species †Alepidophora – type locality for genus †Alepidophora cockerelli – type locality for species †Alepidophora minor – type locality for species †Alepidophora pealei – type locality for species †Aletodon †Aletodon gunnelli – or unidentified comparable form Aleurites †Aleurites glandulosa †Alforjas – tentative report †Alismaphyllites †Alismaphyllites grandifolius †Allantodiopsis †Allantodiopsis erosa †Allognathosuchus †Allognathosuchus polyodon †Allophaiomys †Allophaiomys pliocaenicus †Allophylus †Allophylus flexifolia †Alomatia – type locality for genus †Alomatia fusca – type locality for species Altica †Altica renovata – type locality for species †Alticonus – type locality for genus †Alticonus gazini – type locality for species †Alysia †Alysia exigua – type locality for species †Alysia petrina – type locality for species †Alysia phanerognatha – type locality for species †Alysia ruskii – type locality for species Amara †Amara cockerelli – type locality for species †Amara danae – type locality for species †Amara powellii – type locality for species †Amara revocata – type locality for species †Amara sterilis †Amara veterata – type locality for species †Amartus †Amartus petrefactus – type locality for species †Amauropilio †Amauropilio atavus – type locality for species †Amauropilio lacoei – type locality for species †Amblycorypha – tentative report †Amblycorypha perdita – type locality for species †Amblyteles †Amblyteles pealei – type locality for species †Ambystoma †Ambystoma alamosensis – type locality for species †Ambystoma tigrinum †Amebelodon †Amebelodon floridanus Amelanchier †Amelanchier peritula †Amelanchier scudderi Amia †Ammophila †Ammophila antiquella – type locality for species †Ampelopsis †Ampelopsis acerifolia †Amphechinus †Amphechinus horncloudi †Amphicerus †Amphicerus sublaevis Amphicosmus †Amphicosmus delicatulus – type locality for species †Amphicyon †Amphicyon galushai †Amphicyon ingens †Amphicyrta †Amphicyrta inhaesa – type locality for species †Amphimachairodus †Amphimachairodus coloradensis †Ampliconus – type locality for genus †Ampliconus browni – type locality for species †Anabrus †Anabrus caudelli – type locality for species Anas †Anasa †Anasa priscoputida – type locality for species †Anatis †Anatis resurgens – type locality for species †Anchastus †Anchastus diluvialis – type locality for species †Anchastus eruptus – type locality for species †Anchitherium †Anconatus – type locality for genus †Anconatus dorsuosus – type locality for species †Anconatus niger – type locality for species Andrena †Andrena clavula – type locality for species †Andrena grandipes – type locality for species †Andrena hypolitha – type locality for species †Andrena lagopus †Andrena percontusa – type locality for species †Andrena sepulta – type locality for species †Andrenopteryx †Andrenopteryx willardi †Andrias †Andrias matthewi †Andricus †Andricus myricae – type locality for species †Anelaphus †Anelaphus extinctus – type locality for species †Anemia †Anemia elongata †Angustidens †Angustidens vireti †Anisonchus †Anisonchus athelas – or unidentified comparable form Anisotoma †Anisotoma sibylla – type locality for species †Ankylodon †Ankylodon annectens †Anobium †Anobium durescens – type locality for species †Anomala †Anomala exterranea – type locality for species †Anomala scudderi – type locality for species †Anomalon †Anomalon deletum – type locality for species †Anomalon excisum – type locality for species †Anomalon miocenicum – type locality for species Anser †Antas †Antas crecca Anthaxia †Anthaxia exhumata – type locality for species †Anthaxia prasina †Antherophagus †Antherophagus megalops – type locality for species †Anthidium †Anthidium exhumatum – type locality for species †Anthidium scudderi – type locality for species †Antholithes †Antholithes amoenus †Antholithes pediloides †Anthomyia †Anthomyia atavella – type locality for species †Anthomyia laminarum – type locality for species †Anthomyia persepulta – type locality for species †Anthomyia winchesteri – type locality for species Anthonomus †Anthonomus concussus – type locality for species †Anthonomus debilatus – type locality for species †Anthonomus defossus – type locality for species †Anthonomus evigilatus – type locality for species †Anthonomus primordius – type locality for species †Anthonomus rohweri – type locality for species †Anthonomus soporus †Anthophora †Anthophora melfordi – type locality for species †Antiacodon †Antiacodon pygmaeus Antilocapra †Antilocapra americana †Antocha †Antocha principialis – type locality for species †Apanthesis – type locality for genus †Apanthesis leuce – type locality for species †Apatosciuravus †Apatosciuravus bifax †Aphaena †Aphaena atava – type locality for species Aphaenogaster †Aphaenogaster donisthorpei – type locality for species †Aphaenogaster mayri – type locality for species †Apheliscus †Aphelops †Aphelops malacorhinus †Aphelops megalodus †Aphelops mutilus †Aphidopsis †Aphidopsis margarum – type locality for species Aphodius †Aphodius aboriginalis – type locality for species †Aphodius florissantensis – type locality for species †Aphodius granarioides – type locality for species †Aphodius inundatus – type locality for species †Aphodius laminicola – type locality for species †Aphodius mediaevus – type locality for species †Aphodius praeemptor – type locality for species †Aphodius senex – type locality for species †Aphodius shoshonis – type locality for species Aphrophora Apion †Apion attenuatum †Apion cockerelli – type locality for species †Apion evestigatum – type locality for species †Apocymospermum †Apocynophyllum †Apocynophyllum lesquereuxi †Apolysis †Apolysis magister – type locality for species †Aporema – type locality for genus †Aporema praestrictum – type locality for species †Apsilocephala †Apsilocephala vagabunda – type locality for species †Apternodus †Apternodus iliffensis Aquila †Aquila chysaetos †Araneaovoius †Araneaovoius columbiae Araneus †Araneus absconditus – type locality for species †Araneus cinefactus – type locality for species †Araneus delitus – type locality for species †Araneus emertoni – type locality for species †Araneus kinchloeae – type locality for species †Araneus longimanus – type locality for species †Araneus meeki – type locality for species †Araneus vulcanalis – type locality for species †Archaeochrysa †Archaeochrysa creedei – type locality for species †Archaeochrysa fracta – type locality for species †Archaeochrysa paranervis – type locality for species †Archaeomnium †Archaeomnium brownii †Archaeotherium †Archaeotherium mortoni †Archalia – type locality for genus †Archalia femorata – type locality for species †Archimyrmex – type locality for genus †Archimyrmex rostratus – type locality for species †Archiponera – type locality for genus †Archiponera wheeleri – type locality for species †Archiraphidia †Archiraphidia somnolenta – type locality for species †Archiraphidia tranquilla – type locality for species †Archiraphidia tumulata – type locality for species Arctobyrrhus †Arctobyrrhus subcanus †Arctocyon †Arctocyon mumak †Arctodontomys †Arctodontomys nuptus †Arctodontomys wilsoni †Arctostylops – tentative report †Arfia †Arfia opisthotoma †Arfia shoshoniensis †Argia †Argia aliena – type locality for species †Arhopalus †Arhopalus pavitus – type locality for species †Aristolochia †Aristolochia mortua †Artimonius †Artimonius australis †Artimonius nocerai †Artocarpus †Artocarpus lessigiana †Asilus †Asilus amelanchieris – type locality for species †Asilus curculionis – type locality for species †Asilus florissantinus – type locality for species †Asilus peritulus – type locality for species †Asilus wickhami – type locality for species †Asimina †Asimina vesperalis Asio †Aspicolpus †Aspicolpus repertus – type locality for species †Asplenium †Asplenium delicatula – or unidentified comparable form †Astephus †Aster †Aster florissantia †Asterocarpinus †Asterocarpinus perplexans †Astronium †Astronium calyx †Astronium truncatum Asynarchus Ataenius †Ataenius patescens – type locality for species †Ataenius restructus – type locality for species †Atalantycha †Atalantycha humata – type locality for species †Athalia †Athalia wheeleri – type locality for species Atheta †Atheta florissantensis – type locality for species †Athous †Athous contusus – type locality for species †Athous fractus – type locality for species