Thomas, who's started 23 of 29 games over the past two seasons, suffered a concussion in Sunday's win over Tampa Bay.
Rookie Chastin West was making his first career start in Thomas' place. The Jaguars signed West off Green Bay's practice squad three months ago. He has eight catches for 88 yards in nine career games, all with Jacksonville.
Third-year receiver Taylor Price, claimed off waivers from New England earlier this week, was active.