Thomas G. Osenton has been named president and chief operating officer of Sporting News Publishing Co., effective Aug. 15. Richard Waters, currently president and CEO, has been named chairman of the St. Louis-based publishing firm, which is owned by Times Mirror. He will remain as chief executive until Jan. 1, when Osenton will assume the additional duties of CEO. Osenton is publisher of American Artist Magazine, a Billboard publication. Times Mirror also publishes the Los Angeles Times.