Historical clue formulations

• In need of a haircut, say — 2025-05-11
• Long, thick and unkempt — 2020-02-29
• Like an Old English sheepdog — 2016-08-10
• Scooby-Doo's pal — 2016-02-29
• Unkempt — 2015-12-12
• Like yaks — 2014-07-25
• Hirsute — 2010-12-16
• Rough-napped — 2001-07-01
• Like a yak's coat — 1998-08-11