Related Clues:

• They're full of dates
• Reign
• Precambrian et al.
• Historic spans
• Stretches of time
• Historical times
• Spans of history
• Important historic times
• Distinctive time periods
• Period pieces
• Concerns for Clemens and Rivera
• Time and time again?
• Extended periods
• Paleozoic and Cenozoic
• Key times in history