The Coyotes (4-5, 1-2 Great West) rushed for 334 yards and finished with 569 overall. Isaac Newton ran for 113 yards and a touchdown and quarterback Noah Shepard also ran for a score.
Shepard, who was 19 of 29 with two interceptions, threw a touchdown pass to Will Powell for South Dakota, which led 28-7 at the half. Shepard had 235 yards passing with Tom Flanagan catching nine for 109 yards.
Cade Cooper threw for 278 yards and three touchdowns for Southern Utah (4-5, 2-2). Tysson Poots, who finished with 150 yards receiving, caught two of the TD passes for the Thunderbirds. But South Dakota picked off four Cooper passes.