Historical clue formulations

• Polliwog — 2025-07-13
• One who grows up, then eventually croaks — 2023-06-17
• One on the verge of croaking? — 2013-01-27
• Frog-to-be — 2005-07-26
• Immature swimmer — 2001-09-15
• Creature that loses its tail — 2000-04-08
• Pond denizen — 1996-08-04
• Kermit, once? — 1995-10-13