Dunn went to training camp with the Arizona Cardinals and was cut Aug. 25. He spent time on the practice squads for the Pittsburgh Steelers, Green Bay Packers, Cleveland Browns, Miami Dolphins and New England Patriots last year.
He holds the NCAA record with five kickoff returns for a touchdown with four coming in 2012 for Utah. He caught 31 passes for 355 yards and a touchdown.
He is the second receiver on the practice squad, joining Tim Benford.
Whitlock, a Wylie, Texas, native, joined the Cowboys last week after he was among the final cuts of the Cincinnati Bengals.