Dallas also placed DB Deante Burton and DB Darian Thompson on the practice squad injured list.
Martin, 30, is a former first-round pick of the Cowboys back in 2014. He was in the final year of his four-year, $8.967 million contract when the Cowboys picked up his fifth-year option for the 2018 season.
Martin was set to make $9.341 million for the 2018 season when he agreed to a six-year, $84 million extension that included $40 million guaranteed.
In 2020, Martin appeared in 10 games for the Cowboys, making 10 starts for them at various positions.
Gallup, 25, was drafted by the Cowboys in the third round out of Colorado State in 2018. He signed a four-year deal worth $3,523,980 and received a signing bonus worth $889,980.
Gallup is set to be an unrestricted free agent in 2022.
In 2021, Gallup has appeared in one game for the Cowboys and caught four passes for 36 yards receiving.
We have him included in our Top 50 2022 NFL Free Agents List.