What do the following clues have in common?

1. Geological epoch
2. Sprinter's race
3. Tax payer's tier
4. Cut dramatically
5. Human body part

Answer:

Each clue can be answered with a word that can be represented by an English punctuation mark: (parentheses used for clarity)

1. Period (.)
2. Dash (-) 
3. Bracket ( [ ] )
4. Slash ( / ) 
5. Colon (:)

Credit:
Levi Denham (#1-4)