IRVING (November 26, 2012) -- The next man up for the depleted Dallas defense is Batman. That's the way newcomer Brady Poppinga is looking at it anyway.

Poppinga joined the Cowboys on Monday as the roster replacement for linebacker Bruce Carter, who will miss the rest of the season with a dislocated left elbow. Carter is the fourth starting defender to be placed on injured reserve.

Poppinga says he tried to keep himself in "Batman" shape - ready when called - while sitting out this season. He last played in the 2011 finale with St. Louis.

Dallas is without its top two inside linebackers in Carter and Sean Lee, who injured a toe last month. Dan Connor will be the third defensive play caller at the start of a game Sunday, against Philadelphia.