Dunn became the first Bison player to score four touchdowns since DJ McNorton's effort at Montana State in 2010 in the second round of the FCS playoffs.
Dunn did all his damage in the first half on three carries for 111 yards and three touchdowns and caught a 10-yarder for a score. He scored on runs of 61, 5 and 45 yards.
North Dakota State (3-0) scored five touchdowns in the first quarter and led 49-0 at halftime. The Bison piled up 450 yards of total offense to 57 for Robert Morris (2-2).
The Bison were 10 of 17 on third down conversions with Robert Morris going 0 for 9. The Bison held the ball for just more than 39 minutes.
Cole Blake had 50 yards rushing for Robert Morris.
More AP college football: http://collegefootball.ap.org and http://www.twitter.com/AP-Top25
Torrey's 92-yard TD run helps UNT beat FAU 41-38
DeAndre Torrey had 17 carries for a career-high 187 yards, including a 92-yard touchdown run with 4:06 to play, and North Texas beat UNT 41-38 on Thursday night.
Rutledge recaps Houston's 'Jacket-gate'
Laura Rutledge recaps Houston coach Major Applewhite's confrontation with star player Ed Oliver in Thursday's win.
Oliver-Applewhite drama overshadows Houston win
Scott Van Pelt reviews Houston's win over Tulane in which Ed Oliver stole the attention for arguing with coach Major Applewhite.
UCLA's Bruin Bear statue vandalized in USC colors ahead of rivalry game
Vandals broke into a wooden box intended to protect the Bruin Bear and spray-painted USC colors on the body and foundation of the statue ahead of this week's rivalry game.
Bama's defense taking shape
Marty & McGee discuss the emergence of the Crimson Tide defense and sophomore Quinnen Williams.
Patrick Carr runs for 139 yards; Houston beats Tulane 48-17
Patrick Carr ran for a career-high 139 yards and two touchdowns as Houston rolled to a 48-17 victory over Tulane on Thursday night.