Complex sentence: Ridder was also the owner and publisher of the Saint Paul Pioneer Press, but both papers continued to be published as independent daily newspapers until 1985 when the two papers were merged to become the Saint Paul Pioneer Press and Dispatch.
Split into simpler sentences: Ridder was also the owner and publisher of the Saint Paul Pioneer Press, but both papers continued to be published as independent daily newspapers until 1985. In 1985 the two papers were merged to become the Saint Paul Pioneer Press and Dispatch.