Nick Bosa, the 49ers star pass rusher, suffered a head injury late in the second quarter against the Cowboys and has been ruled out for the game. Bosa was on a pass rush with just over one minute left when he collided with fellow defensive lineman D.J. Jones.The third-year pass rusher was checked in the injury tent, then went to the locker room early. He did not emerge after halftime and was ruled out a short time later.Arden Key will likely take over for the injured Bosa.