The Dallas Cowboys on Friday signed starting nose tackle Jay Ratliff, who took over the position when veteran Jason Ferguson was injured in the opening game of the year, to a five-year contract extension. The deal, first reported by The Dallas Morning News and confirmed for ESPN.com by league sources, is worth $20.5 million and includes $8 million in bonuses. A three-year veteran, Ratliff spent his first two seasons rotating between end and tackle in the Cowboys' 3-4 front. He moved to tackle full-time this year and assumed the No. 1 spot on the nose tackle depth chart when Ferguson suffered a ruptured biceps tendon in the first game of the season.