Complex sentence: However Cinerama and the early 3D films, both launched in 1952, succeeded at the box-office in defying this trend, which in turn persuaded Spyros Skouras, the head of Twentieth Century-Fox, that technical innovation could help to meet the challenge.
Split into simpler sentences: However Cinerama and the early 3D films, both launched in 1952, were defying this trend and seeing success at the box-office. This persuaded Spyros Skouras, the head of Twentieth Century-Fox, that technical innovation could help to meet the challenge.