Related Clues:

• One billion years, in geology
• Quite a while
• See 44-Across
• Significant time
• Proposal defeated in 1982
• Many millennia
• Stat for Maddux
• Long time
• Years and years
• Pitcher's pride
• Cenozoic, e.g.
• Age
• '___ Yes!' (old political placard)
• One for the history books
• Period in history