| Anchitheriinae(noun, creature, appearance, eocene) |
| Ancylopoda(noun, creature, appearance, eocene) |
| Andrias scheuchzeri(expression, creature, appearance, oligocene) |
| Anoplotheriidae(noun, creature, appearance, eocene) |
| Anthracotheriidae(noun, creature, appearance, eocene) |
| Anthracotherium(noun, creature, appearance, eocene) |
| Archaeohyracidae(noun, creature, appearance, paleocene) |
| Archaeohyrax(noun, creature, appearance, eocene) |
| Archaeopithecidae(noun, creature, appearance, eocene) |
| Archaeotherium(noun, creature, appearance, eocene) |
| Arctostylopida(noun, creature, appearance, paleocene) |
| Arsinoitheriidae(noun, creature, appearance, eocene) |
| Asiadapinae(noun, creature, appearance, eocene) |
| Asterostomatidae(noun, creature, appearance, eocene) |
| Astrapotheria(noun, creature, appearance, paleocene) |
| Astrapotheriidae(noun, creature, appearance, eocene) |
| Aturia(noun, creature, appearance, paleocene) |
| Azibiidae(noun, creature, appearance, eocene) |
| Barytherium(noun, creature, appearance, eocene) |
| Basilosaurinae(noun, creature, appearance, eocene) |