Colorado State had fallen behind, 72-68 in the extra period, but rallied to tie the score on Matt Williams' two free throws with 2 minutes, 27 second left, and Ronnie Clark's layin 39 seconds later, knotting the score for the first time in the game.
Wyoming took it's final lead of the night with 1:38 to play on David Rottinhaus' two free throws.
Rams' guard Micheal Morris drew the Rams within a point, 74-73, with 1 minute, 19 seconds to play.
That set the stage for the frantic finish. The Rams missed a pair of field goals to try for the lead and had a turnover, but Boatner forced a turnover with 10 seconds left in the game, drove downcourt and was caught off-balance in the air without a teammate to catch his pass.
The freshman from Lake Charles, La., shot the ball off his team's backboard, followed the shot, and grabbed the rebound to score the winning layin. Wyoming's David Adams' fadeaway 12-footer missed as time expired.
"Dwight Boatner came in and made big play after big play," said Layer. "The last play he had the presence of mind to shoot if off the board. It's often times a freaky play like that that decides these kind of games."
Colorado State won for the third time in a row, and moves to 11-8 overall, 3-3 in the Mountain West Conference. Wyoming is 9-10, 2-4.
Colorado State, playing without injured center Matt Nelson, who has a sprained knee, led 40-31 at intermission, but saw that lead slip away when Wyoming's Alex Dunn hit a short jumper with 5 minutes, 30 seconds to play in regulation to give the Cowboys a 59-58 lead - the fourth lead change of the game.
Dunn had four points during an 8-0 Cowboy run in the game as Wyoming led 63-58 with under four minutes left in eh game. Colorado State fought back within one, 63-63 with three minutes to play on a baskets by Matt Williams and Shelton Johnson.
After a basket by Joe Ries and Straight's layin gave Wyoming a 67-62 lead, the Rams scored the final five points of regulation - in the final 1 minute 54 seconds - on three free throws by Matt Williams and two by Boatner.
Colorado State had possession the final 26.6 seconds of regulation but guard Micheal Morris' baseline jumper was wide, sending the game into the extra period.
Colorado State returns to action Saturday night, Feb. 7, at New Mexico.