Complex sentence: In 2012, the Cavalettes dance/drill team performed at the Tournament of Roses Parade, marking the first time in the history of the parade that a high school drill and dance team performed an opening number.
Split into simpler sentences: In 2012, the Cavalettes dance/drill team performed at the Tournament of Roses Parade. Marking the first time in the history of the parade that a high school drill and dance team performed an opening number.