Thurman made 5 of 10 shots and grabbed six rebounds, and was the only Missouri State player to reach double figures.
Missouri State (9-13, 3-7 Missouri Valley) opened the second half on a 16-6 run to stretch its lead to 39-25 with 11:09 to play. The Bears led by double digits until Jordan Caroline scored and Tyler Smithpeters hit a 3-pointer to pull Southern Illinois within 50-44 with 35 seconds to go.
Caroline and Smithpeters scored 14 points apiece to lead Southern Illinois (9-14, 2-8).
Anthony Beane added 11 points for the Salukis, who shot just 14 of 42 (33 percent) from the floor for their third straight loss.