49ers sign defensive lineman who’s familiar with SF defense

With three defensive linemen out with injuries, the 49ers on Wednesday signed Sen'Derrick Marks, a former second-round pick familiar to defensive coordinator Robert Saleh, to a one-year deal.

The 49ers had worked out three defensive linemen on Tuesday, including Tyson Jackson, the third overall pick in the 2009 draft.

Marks' eight-year career has been split between the Titans and Jacksonville Jaguars, who in recent seasons used the same defense the 49ers are implementing this year. Their former coach, Gus Bradley, was the Seahawks’ defensive coordinator when Saleh was a quality control coach in Seattle.

Saleh, the 49ers defensive coordinator this year, is implementing a Seattle-style system. He was Jacksonville’s linebackers coach for the last three seasons.

Marks (6-2, 302) started all 16 games for Jacksonville in 2013 and 2014, and he led the team with 8 1/2 sacks in 2014. However, he started only three games the last two seasons due to injuries and after the Jaguars brought in other, more prominent players at his position.

Marks, 30, likely will line up at defensive tackle in the 49ers' defense.

The starter there, DeForest Buckner, has been out of action with an ankle injury for much of August. Defensive ends Aaron Lynch (ankle) and Ronald Blair (groin) also have missed recent practices.

The 49ers had two open roster spots after waiving linebackers Donavin Newsom (concussion) and Jayson DiManche (hamstring) last week. They reached an injury settlement with DiManche while Newsom, the rookie involved in the scary collision earlier this month, will spend the year on injured reserve.

This story was originally published August 23, 2017 at 10:03 AM.