The San Francisco 49ers on Tuesday officially placed defensive tackle Gracen Halton on season-ending injured reserve.

Halton suffered a broken ankle in the 49ers' Week 9 win over the Las Vegas Raiders. Head coach Kyle Shanahan on Sunday after the game indicated the injury would end Halton's promising rookie season.

There was no corresponding move just yet for San Francisco which means they have a roster spot open. That spot will probably go to wide receiver Keenan Allen who the 49ers acquired in a trade just before Tuesday's trade deadline. As for a direct replacement for Halton, second-year DT CJ West is due to return from IR after suffering a knee injury in Week 2. The 49ers won't have to clear a roster spot for West until Saturday if they plan to activate him for Sunday's game against the Dallas Cowboys.

Halton's injury is a particularly brutal blow to the 49ers' defensive front which was just starting to come together following the addition of DeForest Buckner. Now the promising fourth-round pick is done for the season. His first year as a pro featured eight productive games with two starts. Halton put up 15 tackles, five tackles for loss, 2.0 sacks, one pass breakup, one forced fumble and a fumble recovery that resulted in a touchdown.