| bygone(adjective, original, old, past, venerable) |
| foremost(adjective, beginning) |
| nascent(adjective, beginning) |
| old-time(adjective, last, original, past, primitive) |
| olden(adjective, original, old, past, primitive) |
| past(adjective, last, original, past, primitive) |
| previous(adjective, last, past, first, primary) |
| primogenial(adjective, head, beginning, opening, original) |
| starting(adjective, beginning, first, previous, initial) |
| undeveloped(adjective, immature) |
| Noachian |
| alpha(adjective, beginning) |
| baby(adjective, beginning) |
| basal(adjective, important, significant, original, essential) |
| budding(adjective, beginning) |
| commencing(adjective, beginning, first, previous, initial) |
| crucial(adjective, important, significant, original, essential) |
| earlier |
| fossil(adjective, oldness) |
| immemorial(last, original, past, primitive, venerable) |