Historical clue formulations

• *Period for Fred, Wilma and Pebbles (2016, 2023) — 2026-03-09
• Phase + 1 = Ancient period — 2023-05-23
• Primeval — 2022-07-31
• Primitive time — 2022-04-10
• When the Lascaux caves were painted — 2021-07-25
• Time before computers, facetiously — 2021-03-28
• Very primitive — 2016-09-29
• Primitive — 2016-08-20
• Primitive and backward — 2016-03-25
• Fred and Barney's time — 2014-03-05
• Smelting ended it — 2013-02-15
• Primitive — 2012-08-11
• Much simpler time — 2011-04-22
• Caveman's era — 2007-10-29
• Primitive — 2007-04-28
• It started about 2 1/2 million years ago — 2006-02-05
• "The Flintstones" setting — 2004-02-03
• Early time — 2001-07-07
• Alley Oop's time — 2000-03-21
• Primitive time — 1998-05-31
• Rocky period? — 1998-05-09
• Primitive time — 1995-09-24
• Neolithic period — 1995-07-02