Did Julius Caesar use the trebuchet?

I'm doing a report on who would win in a fight; Leonidas and the Spartans, Julius Caesar and his Legions, or Genghis Khan and his Mongolians. I'm trying to figure out what long-range weapons they had. I know they had long-bows, giant crossbows, and I'm wondering if they used the trebuchet or anything else for long-range, but it has to be during when Julius Caesar was in charge.