Sam, the first openly gay player in the NFL, was signed to the team's practice squad Sept. 3. He never made it to the Cowboys' active roster.
According to the team's official website, Sam will be replaced on the practice squad with linebacker Troy Davis, who worked out for Dallas on Monday.
I want to thank the Jones family and the entire Cowboys organization for this opportunity, as well as my friends, family, teammates and fans for their support. While this is disappointing, I will take the lessons I learned here in Dallas and continue to fight for an opportunity to prove that I can play every Sunday.
60 Greatest NFL Photos
Bobby Layne led the Detroit Lions to NFL titles in 1952 and '53, but had to settle for a conference crown in '54.
Colts back Alan Ameche scored the winning touchdown against the Giants in the NFL Championship, labeled ''The Greatest Game Ever Played.''
Eagles linebacker Chuck Bednarik knocked Giants back Frank Gifford out of the game ... and the following season.
Jim Taylor could grind out yardage for Green Bay even when the tundra wasn't frozen.
The Colts' Jimmy Orr beat tight coverage for a touchdown catch against the 49ers.
The Packers' grasp exceeded their reach as they tried to knock down a chip shot by 49ers kicker Tommy Davis.
Browns back Jim Brown tries for a touchdown against the Colts during the 1964 NFL Championship at Municipal Stadium in Cleveland.
Packers linebacker Ray Nitschke recovers a Jim Brown fumble during the NFL Championship at Lambeau Field.
Jerry Kramer (64) and Forrest Gregg carry Vince Lombardi off the field after Green Bays' second straight Super Bowl triumph and Lombardi's final game as the Packers' coach.
Pete Beathard (11) called the Oilers' play as this shot was snapped from a catwalk inside the Astrodome.
John Mackey (88) and Johnny Unitas (19) huddle with their fellow Colts during practice at Memorial Stadium, shot with a fisheye lense.
Dick Butkus made eight straight Pro Bowls and led the Monsters of the Midway in intimidation for nine years.
Broadway Joe offered reporters, including Brent Musburger (left), a guarantee: the underdog Jets would shock 18-point favorite Baltimore in Super Bowl III.
Vikings back Dave Osborn took a lick from the Rams' Deacon Jones (75) but still scored.
Eight months after Super Bowl IV, Dave Osborn and the Vikings avenged their loss to Willie Lanier (63) and the Chiefs.
The Colts' margin of victory over the Cowboys in Super Bowl V was provided by Jim O'Brien on this field goal.
Mean Joe Greene, the first pick in the '69 draft, became the cornerstone of a Steelers team that dominated with defense and won four Super Bowls.
Packers tackle Mike McCoy had mayhem in mind but couldn't reach 49ers quarterback Steve Spurrier before he let it fly.
The Dolphins' Manny Fernandez (75) pursues Redskins quarterback Billy Kilmer in Super Bowl VII.
Don Shula celebrates with his Dolphins, who capped off their undefeated season -- still unmatched in NFL history -- with a win in Super Bowl VII.
The Mayhem of football took a toll on the hands of Steelers defensive end L.C. Greenwood.
O.J. Simpson broke Jim Brown's single-season rushing record with this carry, and ended the season with 2,003 yards.
Mercury Morris helped the Dolphins dominate Jim Marshall (70) and the Vikings in Super Bowl VIII.
Jets quarterback Joe Namath listens on the sidelines during a messy game against the Bills at Shea Stadium.
Steelers wideout Lynn Swann laid out the Cowboys in Super Bowl X in Miami, and was the game's MVP.
Tight end Jackie Smith flops in the end zone after dropping a potential game-tying touchdown. Dallas had to settle for a field goal en route to losing Super Bowl XIII 35-31.
Dwight Clark's last-minute catch beat the Cowboys and put the 49ers in the Super Bowl.
49ers fullback Earl Cooper celebrates after scoring a 10-yard receiving touchdown in the second quarter of Super Bowl XVI.
The Chargers' Mike Williams got up high to cover Dolphins tight end Bruce Hardy, who went even higher for this catch.
Walter Payton went around, through and sometimes over the defense to pick up precious yards.
The Bears' Reggie Phillips returned this interception for a TD in Chicago's rout of the Patriots in Super Bowl XX.
Referee Jack Vaughn tries to follow an Eagles' field goal attempt during the Fog Bowl, an NFC divisional playoff game against the Bears.
With only 3:10 left in the game, Joe Montana marched the 49ers 92 yards down the field to beat the Bengals 20-16 in Super Bowl XXIII.
Raiders quarterback Jay Schroeder was an unlucky 13 when Bills defenders put a new twist on the old gang tackle.
The Cowboys' Emmitt Smith ran into heavy traffic while the Giants' Lawrence Taylor tried to run into Smith.
Hats off to Raiders linebacker Mike Jones for not flagging the ref for holding on this play.
Dan Marino had to contend with the Patriots' rush and a ravaged field in Miami.
Barry Sanders ran circles around NFL defenses with an electrifying style unlike anything the league had seen.
The Bears' Chris Zorich felt the chill of 15-degree weather in December, in Green Bay.
Chiefs back Marcus Allen scored the 100th of his 123 career rushing TDs, in Denver.
Chiefs cornerback Dale Carter was stretched to the limit when he broke up this pass to Packers wideout Don Beebe.
Jaguars quarterback Mark Brunell went up and over two Browns to reach the end zone in Cleveland.
Steve McNair paid a high price to reach paydirt against the Steelers.
All hands were on deck--and on Aaron Brooks (2)--as the Giants' defense scuttled the Saints' quarterback.
Vikings wideout Randy Moss took matters into his own hand to make this reception against the Steelers.
Dolphins tight end Randy McMichael soars over Saints defenders to score during a preseason game.
Steelers wideout Antwaan Randle El provided a turning point of sorts when he was face-masked by the Browns' Chris Akins.
Titans receiver Justin McCareins had a meeting of the minds with Panthers linebacker Mike Caldwell (59) and safety Jarrod Cooper.
The pylon left no doubt that Bengals running back Jeremi Johnson had scored against the Chiefs in Cincinnati.
Tom Brady and the Patriots rush the field after defeating the Panthers 32-29 in Super Bowl XXXVIII.
Chargers back LaDainian Tomlinson stiff arms Rams saftey O.J. Atogwe as he takes off on a 38-yard touchdown run.
Giants wideout David Tyree secures a catch with his helmet against Patriots safety Rodney Harrison in Super Bowl XLII.
Wideout Santonio Holmes's leaping touchdown grab with 42 seconds remaining gave the Steelers a 27-23 win over the Cardinals in Super Bowl XLIII.
Ravens wideout Derrick Mason rolls over in end zone after making a touchdown catch as Patriots safety Brandon Meriweather watches.
Buccaneers linebacker Geno Hayes got upended during a field goal attempt by the Packers.
Packers cornerback Charles Woodson returns an interception 48 yards for a touchdown against the Lions at Lambeau Field.
Browns wideout Mohamed Massaquoi sustained a concussion on this hit by Steelers linebacker James Harrison.
Jets linebacker David Harris rips the helmet off Patriots tight end Aaron Hernandez as he makes the tackle.
Giants back Ahmad Bradshaw scores with 57 seconds left in Super Bowl XLVI as he tried to stop himself from falling into the end zone to kill the clock.
Redskins quarterback Robert Griffin III stepped out of bounds before making a dive towards the end zone against the Bengals.
Sam made history and received national attention in the spring when he announced he was gay several weeks before the NFL combine. As the reigning SEC co-defensive player of the year at Missouri, Sam became the highest-profile active gay football player and sought to become the first gay player to be selected in the NFL Draft.
The St. Louis Rams picked Sam in the seventh round of this year's draft and kept him on their roster until the last round of cuts at the end of training camp. He was picked up by the Cowboys several days later.
At the time of Sam's signing, Cowboys owner Jerry Jones said Sam "had a long way to go" as a player while dismissing concerns that the rookie could be a potential distraction in the locker room due to his sexuality, echoing the sentiments of Rams coach Jeff Fisher from when Sam was with St. Louis.
Jones said Sunday that Sam's sexual orientation was "a dead issue."
Sam is now free to sign with any other team or join any other team's practice squad. The CFL could also be an option, as Sam reportedly received interest from the Montreal Alouettes before he joined the Cowboys' practice squad.
- Ben Estes