"I'm sure he'll get surgery within the next couple of weeks and have to go on IR," Shanahan told reporters after Friday's practice.
Shanahan was asked how the injury occurred.
"No one fell on it," he responded. "Two people, him and an O-lineman pushing on each other, and came to a stop, and [the knee] just gave out. It was a real unfortunate one."
Shanahan said the team plans to promote defensive lineman Kevin Givens from the practice squad to take Taylor's roster spot.
"Kevin had a good training camp, was close to making our roster," Shanahan said. "He sat here and worked all year to get better, and he's been waiting for this opportunity, and he got it yesterday."
Givens has "a chance to be" active on Sunday against the Seahawks, Shanahan added.
Taylor, 24, was working his way back from a ligament injury in his elbow and was inactive for the 49ers' last three games.
The loss of Taylor is another hit to the defensive line's once-strong depth. The unit has already lost Ronald Blair, D.J. Jones, and Damontre Moore for the season. Pass rusher Dee Ford, whom the team traded for in March, has missed four of the last five games and isn't expected to be available until the playoffs.
The 49ers made Taylor a seventh-round selection out of Temple last year. He registered nine combined tackles and a pass defensed through six games this season and has recorded 16 combined tackles and a pass defensed through his two NFL seasons.
San Francisco signed Givens, 22, in April as an undrafted free agent out of Penn State. He registered 33 combined tackles, 10.5 for a loss, five sacks, and a pass defensed as a junior in 2018.
The 49ers waived Givens on August 31 and then signed him to the practice squad the next day.
Related News
More San Francisco 49ers News
-
49ers re-signing DT Kevin Givens to a one-year deal
The San Francisco 49ers are re-signing defensive tackle Kevin Givens to a one-year deal, with Matt Barrows of The Athletic being the first to report the news. 49ers are bringing back DT Kevin Givens on a one-year deal. Givens had 3 1/2 sacks last season.— Matt Barrows... -
49ers signing RB Patrick Taylor to a one-year extension
NFL insider Tom Pelissero reports that the San Francisco 49ers are signing running back Patrick Taylor to a one-year extension. He was scheduled to become an unrestricted free agent on Wednesday. The #49ers and RB Patrick Taylor, Jr. have agreed to a 1-year extension. Deal... -
Vikings signing potential 49ers free-agent target, DT Jonathan Allen
According to NFL insider Ian Rapoport, the Minnesota Vikings are signing former Washington Commanders defensive tackle Jonathan Allen, a two-time Pro Bowler, to a three-year, $60 million deal. The Commanders recently released Allen, freeing up an estimated $16.5 million in... -
Should the 49ers pursue recently-released DT Jonathan Allen?
The San Francisco 49ers are in dire need of reinforcements along the defensive line, and a prominent name just hit the market. The Washington Commanders are releasing two-time Pro Bowl defensive tackle Jonathan Allen, freeing up an estimated $16.5 million in salary cap...