Lions cut Gaines
Gaines signed a four-year contract last year as a free agent from Buffalo, but was plagued by drops and fumbles in his first season as a Lion. He finished with 23 catches last year.
Pettigrew isn't a down-the-field threat like Antonio Gates, but he was regarded as the most complete tight end in the draft.
"If you look back over the last few years, there's not many tight ends that have looked like him that have blocked him that have come out," Lions coach Jim Schwartz said. "If you're going to run the football, which we're going to do, you need a guy that can block the edge. And he's a guy that can do that.
"He's a really, really big target in the passing game. He's got really soft, reliable hands. Not necessarily a vertical threat down the field, but going to be a good target in the red zone."
The Lions also signed blocking tight end Will Heller as a free agent this offseason.