Mercury Morris, the NFL running back and kick returner who played on the iconic, undefeated 1972 Miami Dolphins, has died. He was 77.

The Pittsburgh native played for the Dolphins from 1969 to 1975, winning back-to-back Super Bowls with the team in 1972 and 1973 under coach Don Shula.

Dolphins legend dies

Along with Larry Csonka and Jim Kiick, Morris was part of what became known as "the perfect backfield."

The Dolphins' 1972 season remains the only perfect season in NFL history. Morris ran 1,000 yards that year, a career best, and led the NFL in rushing touchdowns with 12 that season.

“Morris left a lasting impact through his dynamic play, personality and record-breaking performances,” the Dolphins said. “He loved the Dolphins, the fans and the community of South Florida and will forever be remembered as one of the greatest players to don the aqua and orange.”

Morris, who played college football with West Texas A&M, was also selected for three Pro Bowls during his pro career. In a statement, Morris' family said his “talent and passion left an indelible mark on the sport.”

“Beyond the field, Mercury was a devoted father, a loving brother, a loyal friend, and a pillar in the community,” his family wrote in the statement. “His presence extended far beyond football, as he touched the lives of many throughout his time in Miami.”

Teammate reacts

In 1972, Morris and fullback Larry Csonka became the first duo to rush 1,000 yards each in a season.

“It's a very sad day for me and our Dolphin family," Csonka said in reaction to Morris' death.

In 1982, Morris was convicted on a drug trafficking charge over a $120,000 deal and sentenced to 20 years in prison. Morris admitted to using cocaine to manage pain but denied dealing the drug.

The Florida Supreme Court overturned the conviction after he served over three years in jail, and he was freed from prison under a plea bargain agreement. He went on to become a motivational speaker.

“Was I bitter? Not really,” Morris wrote in his book Against The Grain published in 1998. “I would not recommend three days in jail to anyone, much less three years. But I must be honest: I needed to go through what I did to develop the character I had when I became a free man.”

Morris is survived by five children - Geno, Maceo, Tiffany, Troy and Elliott, and three siblings.