Thomas' first practice wasn't a full one, according to Chris McCosky. Thomas only took part in the Lions' individual drills, indicating that he's not quite ready to go through a full practice just yet. I suppose that makes sense considering he missed more than a week of training camp before even hitting the practice field at all.
Earlier this week, the Lions activated center Leroy Harris from the PUP list and defensive end Ronnell Lewis from the NFI list. These two players, in addition to Thomas, were the only Lions on injury lists going into training camp, and now all are active. As a result, this means there won't be a situation like last year where Chris Greenwood stayed on the PUP list for the entire season.
Now that Thomas is able to practice, he's got some serious ground to make up if he wants to make the 53-man roster. The expectation all along has been that he will have to impress on special teams to have a legitimate shot at making the team, and that remains the case as the first preseason game approaches.