Ameer Abdullah’s stay on the San Francisco 49ers’ active roster was brief as the veteran running back was placed on season-ending injured reserve on Monday after a rib issue sustained in Saturday’s preseason opener against the Denver Broncos.

The 49ers, who signed Abdullah on July 31, inked running back Jeff Wilson Jr. and defensive lineman Trevis Gipson to one-year contracts on Monday. The team cut quarterback Tanner Mordecai and activated offensive lineman Andre Dillard from the physically unable to perform list.

Head coach Kyle Shanahan said on Monday that rookie wide receiver Jordan Watkins is expected to be out about a month due to a high ankle sprain and that former starting receiver Brandon Aiyuk (ACL) is estimated to return around Week 6 of the regular season, though the situatio

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