Cowboys sign defensive end; Kowalski hurt

OXNARD, Calif. -- The Cowboys officially signed defensive end Toby Jackson on Wednesday and released defensive lineman Ike Igbinosun, who was battling a lower leg injury.

Jackson, who didn't play last season at the University of Central Florida for academic reasons, was one of four players to work out for the Cowboys on Tuesday.

In 2011, Jackson played in nine games for UCF and had 14 tackles, three tackles for loss and one blocked punt. He was eligible for the NFL's supplemental draft this summer but wasn't selected.

Also, Cowboys right guard Kevin Kowalski bruised a knee during a pass-rush drill and will be out two to four weeks.

Kowalski was sharing first- and second-team snaps with David Arkin. Arkin received all the snaps with both units after Kowalski's injury.

The Cowboys are also without center Ryan Cook (conditioning), guard Ray Dominguez (shoulder), tackle Jermey Parnell, guard Mackenzy Bernadeau (hamstring) and tackle Demetress Bell (conditioning) along the offensive line.