Tomlinson was acquired on August 31, 2017, via a trade with the Detroit Lions, while Cooper signed a one-year deal with the team on March 20.
Of course, the slated starters could change through the course of the offseason. The 49ers also have guards Zane Beadles and Erik Magnuson on the roster and may add more competition via next month's draft.
There is also Joshua Garnett, who the 49ers selected with the 28th-overall pick in 2016. He will have an opportunity to compete at both spots, Shanahan said. The 49ers placed Garnett on season-ending injured reserve on September 2, 2017, after the guard injured his knee during a training camp practice and had surgery on August 10, 2017, to "clean out" the knee.
Garnett started 11 games for the 49ers as a rookie in 2016.
"We challenged Josh," Shanahan told Joe Fann of 49ers.com on Monday. "We wanted him to take the year to get his body in the best shape possible. Seeing him at the end of the year in December, it looked like he took advantage of his time off. He got his body fat down and his weight down. I think he's in the best shape of his life, and he's given himself a chance to help us this year."
Cooper is also coming off of a knee injury sustained during Week 17 with the Dallas Cowboys. He had MCL surgery in January, according to a report by ESPN, but is expected to be ready to participate in the team's offseason program, which is scheduled to kick off on April 16.
"Number one, he's got to get himself healthy," 49ers general manager John Lynch said last week at Stanford's pro day. "He had his surgery right after the season, so there's some work to be done there."
Lynch said the 49ers would be conservative in their approach to make sure Cooper returns healthy.
"He played very well, in our minds, for Dallas last year," he continued. "Kind of resurrected his career."
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