Gifford was injured in the first half of a 44-21 win over the Los Angeles Rams on Sunday. Gifford, who missed the early part of the season after breaking an ankle in a preseason game, was placed on season-ending injured reserve.
The Cowboys have already been without second-year linebacker Leighton Vander Esch because of a neck injury. It’s unclear whether he will play again this season. Veteran Joe Thomas injured a knee against the Rams.
Smith was the MVP of the 2014 Super Bowl with Seattle, returning an interception 69 yards for a touchdown and recovering a fumble in the Seahawks’ 43-8 rout of Denver.
The 30-year-old Smith was never a full-time starter in Seattle before starting 30 of 31 games in two seasons with Oakland.
Jacksonville added Smith in November but waived him after he appeared in two games. Smith has started half of his 102 career games over eight seasons. He also played for San Francisco.
Dallas and Philadelphia are tied for first in the NFC East at 7-7 and playing each other Sunday. The Cowboys make the playoffs if they win.
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