The Dallas Cowboys have signed defensive linemen Landon Cohen and George Selvie and released receiver Lavasier Tuinei.

The additions of Cohen and Selvie on Wednesday give the Cowboys depth while the defensive front deals with injuries.

Defensive end Anthony Spencer is having arthroscopic knee surgery Thursday and is likely out for the rest of training camp. Defensive tackle Jay Ratliff could be out another two weeks with a hamstring injury.

Tyrone Crawford is out for the season after tearing his left Achilles tendon in the first full workout of camp.

Selvie played in nine games for Jacksonville last year. He was drafted by St. Louis in 2010 and also played for Carolina.

Landon last played in 2011 with New England.

Tuinei never passed the conditioning test after signing Sunday.