MIAMI GARDENS, Fla. -- Eugene "Mercury" Morris, who starred for the unbeaten 1972 Miami Dolphins as part of a star-studded backfield and helped the team win two Super Bowl titles, has died, the team said Sunday.

Morris, a three-time Pro Bowl selection, was 77.

In a statement, his 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. "His presence extended far beyond football, as he touched the lives of many throughout his time in Miami."

We are deeply saddened by the passing of Dolphins great Mercury Morris. pic.twitter.com/V2t8SFNVvf

Miami Dolphins (@MiamiDolphins) September 22, 2024

Morris was the starting halfback and one of three go-to runners that Dolphins coach Don Shula used in Miami's back-to-back title seasons of 1972 and 1973, alongside Pro Football Hall of Famer Larry Csonka and Jim Kiick. Morris led the Dolphins in rushing touchdowns in both of those seasons, finishing with an NFL-best 12 in 1972 and then 10 more in 1973.

"It's a very sad day for me and our Dolphin family," Csonka posted to X.

Those two seasons -- the best in Dolphins history -- just happened to be the best of Morris' eight-year career as well. He rushed for a career-best 1,000 yards in 1972 then ran for 954 more along with a league-best 6.4 yards per carry the following season.

Morris wasted no time making an impact on the Dolphins. In the first game as a rookie in 1969, he ran back a kickoff 105 yards for a touchdown against Cincinnati. That remains the longest in team history, and both his three career kick return TDs and average of 26.5 yards per return also are team records.

"I think Shula gave everybody a different kind of direction and purpose being coached by this guy," Morris said in 2008. "We were middle-class people and middle-class fans, and Shula was a blue-collar worker. And he had kind of a work ethic that really allowed you to see that if you work hard and you do what you're supposed to do, then things are going to turn out for you -- not all the time but you adjust to that and do what's necessary to try to do as best you can."

Morris made no secret of the fact that he was filled with pride about the 1972 Dolphins being the first -- and still only -- undefeated and untied team in NFL history, pulling off a truly perfect season.

He also tried to make this clear: No, the Dolphins were not rooting against the teams that came close to matching their feat of perfection or had champagne on ice waiting for the moment that the last unbeaten team in a season gets defeated.

"And for the record, we DO NOT TOAST every time an unbeaten team loses," Morris posted on social media in 2015, when the Cam Newton-led Carolina Panthers started 14-0 before losing the next-to-last game of their regular season. "There's no champagne in my glass, only Canada Dry Ginger ale! Ha!"

That sense of humor got pointed at his beloved Dolphins at times. When Miami was 0-8 in the 2007 season, on its way to a 0-13 start and 1-15 record, Morris offered another of his many memorable quips.

"The Dolphins are not embarrassing me, because our record's at the top of the heap," Morris said. "That's not my team. People say, 'Your team is doing bad.' I say, 'My team all has AARP cards.'"

Morris had some personal struggles after his football career ended, most notably being sentenced to 20 years in prison after his 1982 conviction on cocaine trafficking charges. He fought the conviction, admitting he used cocaine -- in part to deal with numerous lingering injuries -- but never sold the drug. His conviction was overturned by the Florida Supreme Court in 1986, and Morris became a motivational speaker urging people to avoid drugs.

"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 went into the Dolphins' Walk of Fame in 2013. He remains fourth on the team's all-time rushing list with 3,877 yards behind Csonka (6,737), Ricky Williams (6,436) and Ronnie Brown (4,815).

"Morris left a lasting impact through his dynamic play, personality and record-breaking performances," the Dolphins posted to X. "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."

The Associated Press contributed to this report.