The Dallas Cowboys traded a seventh-round pick in the 2013 draft to the Miami Dolphins for backup center Ryan Cook. The Cowboys, thinned by injuries to interior offensive linemen since the start of training camp, are likely to use Cook at center and as a "swing" backup who played offensive tackle in college and was a second-round pick of the Vikings in 2006. Among Cook's 40 career starts, he has played right guard, right tackle and center. The Cowboys might not know the status of starting center Phil Costa (back) until early next week. It's possible Cook or David Arkin, a guard who moved to center when Costa first experienced back issues, will play a significant role in Wednesday's season opener against the Giants. With the trade, the Dolphins now have 11 total draft picks in 2013, including an additional third-round pick in the deal that sent Brandon Marshall to the Chicago Bears.