Complex sentence: On May 14,2011, SkyScreamer officially opened at Six Flags St. Louis, where it replaced the Riverview Racer, which was removed at the end of the 2010 season.
Split into simpler sentences: On May 14,2011, SkyScreamer officially opened at Six Flags St. Louis. It replaced Riverview Racer which was removed at the end of the 2010 season.