Because the Detroit Lions don't play until Monday night, they have an extra day to get ready for this week's game. Some teams decide to just push everything back a day to get ready for a Monday night game, but the Lions held a practice on Wednesday like usual.
While it is believed that Wednesday's practice was a bit lighter than a typical one considering so many players sat it out, the Lions did get rookie defensive tackle Nick Fairley back on the field. He participated in practice on a limited basis on the Friday before the Vikings game, leading some to believe he could play against the Cowboys. He didn't after not practicing all week, so it's a good sign that he was back on Wednesday.
Although Fairley did practice, that doesn't necessarily mean he will make his debut for the Lions on Monday. For the last month it has seemed like the Monday night game was a good time for his debut, but Jim Schwartz made it clear that he isn't going to go from "zero to 100 without taking some steps along the way." I suppose we will have to wait and see if he practices the rest of the week before getting a better idea about his status for Monday.
The list of players missing from Wednesday's practice includes offensive tackle Jason Fox, linebackers Stephen Tulloch and Justin Durant (he hasn't been cleared to practice, according to Chris McCosky), wide receivers Calvin Johnson, Titus Young and Rashied Davis and safety Erik Coleman. Amari Spievey left practice after stretching.
Several players out on Wednesday were likely just getting a day off. Others, such as Durant, Davis and Coleman, were out because of injuries rather than rest.