Complex sentence: John Conyers, the Dean of the United States House of Representatives, administered the oath of office to Paul Ryan who, in turn, administered the oath of office en masse to the rest of the members of the 115th Congress.
Split into simpler sentences: John Conyers, the Dean of the United States House of Representatives, administered the oath of office to Paul Ryan. Ryan, in turn, administered the oath of office en masse to the rest of the members of the 115th Congress.