| Anaptomorphinae(noun, creature, geohistory, paleocene) |
| Andrewsarchus(noun, creature, geohistory, lutetian) |
| Andrias scheuchzeri(expression, creature, geohistory, oligocene) |
| Anomalure(noun, creature, geohistory, eocene) |
| Anomaluromorpha(noun, creature, geohistory, eocene) |
| Anseranatidae(noun, creature, geohistory, eocene) |
| Anthidium exhumatum(expression, creature, geohistory, priabonian) |
| Anthidium scudderi(expression, creature, geohistory, priabonian) |
| Anthropornis(noun, creature, geohistory, priabonian) |
| Apidium(noun, creature, geohistory, priabonian) |
| Apogon(noun, creature, geohistory, eocene) |
| Arachnopusiidae(noun, creature, geohistory, eocene) |
| Araliaceae(noun, creature, geohistory, eocene) |
| Archaeohyracidae(noun, creature, geohistory, paleocene) |
| Archaeonycteridae(noun, creature, geohistory, ypresian) |
| Arctoidea(noun, creature, geohistory, eocene) |
| Arctostylopida(noun, creature, geohistory, paleocene) |
| Argyropelecus(noun, creature, geohistory, eocene) |
| Arsinoitherium(noun, creature, geohistory, priabonian) |
| Astrapotheria(noun, creature, geohistory, paleocene) |