The Horned Frogs (3-3, 1-2 Mountain West Conference) scored back-to-back touchdowns in the fourth quarter, but that wasn't enough to cross an 18-point gap Wyoming (4-1, 1-0) created on two touchdowns and a field goal earlier in the half.
Marsh was wide open in the third quarter for an 8-yard catch and a score of 14-6, ending a 47-yard drive that began when Cowboys cornerback Michael Medina picked off Andy Dalton.
On the Cowboys' next possession, three pass interference calls against TCU helped move Wyoming to the Frogs' 2-yard line. Seldon ran in for a 21-6 Cowboys lead.
Seldon finished with 100 yards rushing; Moore had 135.
Billy Vinnedge kicked a 23-yard field goal for a 24-6 Cowboys lead in the fourth quarter.
But TCU fought back, scoring the final 15 points.
On TCU's next possession, Bart Johnson caught a 5-yard pass for the final score.
Marsh's first touchdown, a 65-yard reception, put Wyoming ahead 7-3 in the first quarter.
TCU came within 7-6 on a 32-yard Chris Manfredini field goal at the end of the first half. Manfredini also kicked a 51-yarder, a career best, on the Frogs' first possession.
It was the 300th football game played in War Memorial Stadium. Wyoming's record in the stadium is 203-90-7.
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