The last sentence here – supplemental – what distinguishes it from a sentence that would cause a comma splice?
If I was to write - it was the most fitting conclusion... it would become a comma splice and need a semi-colon.
winning his favorite competition, the long jump, and bringing home another Gold Medal for the United States, the most fitting conclusion to his brilliant career in track and field.
Source: http://grammar.ccc.commnet.edu/grammar/run-on.htm (full sentence)
also: would this last sentence take a dash instead of a comma? Would either be correct?