| Adilophontes(noun, creature, geohistory, rupelian) |
| Aeluroidea(noun, creature, eocene, geogistory) |
| Afrotarsius(noun, creature, geohistory, eocene) |
| Alagomyidae(noun, creature, geohistory, paleocene) |
| Albatross(noun, creature, eocene, geogistory) |
| Alligator(noun, creature, eocene, geogistory) |
| Ambulocetidae(noun, creature, geohistory, eocene) |
| Ameiurus(noun, creature, eocene, geogistory) |
| Amynodontidae(noun, creature, geohistory, eocene) |
| Anaptomorphinae(noun, creature, geohistory, paleocene) |
| Anchitheriinae(noun, creature, geohistory, eocene) |
| Ancylopoda(noun, creature, geohistory, eocene) |
| Anoplotheriidae(noun, creature, geohistory, eocene) |
| Anthracotheriidae(noun, creature, geohistory, eocene) |
| Anthracotherium(noun, creature, geohistory, eocene) |
| Aplodontiidae(noun, creature, eocene, geogistory) |
| Archaeohippus(noun, creature, geohistory, chattian) |
| Archaeohyracidae(noun, creature, geohistory, paleocene) |
| Archaeohyrax(noun, creature, geohistory, eocene) |
| Archaeopithecidae(noun, creature, geohistory, eocene) |