The Miami Dolphins beat the Dallas Cowboys, 28-21, tonight before 74,139 in the Orange Bowl and ended the Cowboys' hopes for a spot in the playoffs as a wild-card team. With the victory, the Dolphins (14-2) secured the home-field advantage throughout the AFC playoffs.

Miami quarterback Dan Marino threw four touchdown passes, the last for 63 yards to Mark Clayton with less than a minute to play.

The last previous time the Cowboys (9-7) failed to make the playoffs was in 1974. Their defeat gave the New York Giants a spot in the Dec. 23 wild-card game against the Rams in Los Angeles. The Giants (9-7) will be making only their second trip to the playoffs in 21 years.

"Adversity is being placed in tough situations and overcoming them," Dallas Coach Tom Landry said. "Unfortunately, we came a few points short tonight . . . It was a hard way to lose a game. We always measure success by the final score; we don't measure it by what we do during the game . . . You live and you die. We died."

Marino completed 23 of 40 passes for 320 yards. Coming into the game, he needed only 59 yards to break Dan Fouts' single season record of 4,802. Marino ended the regular season with a remarkable 5,084 yards, and his performance in the final period was sensational.

"That's real nice and exciting for me to break records like that," he said. "But it's even more exciting to be on a winning team that's going to the playoffs."

Miami Coach Don Shula said, "This was a heckuva win and it came at the right time because we've been struggling. Dan Marino just kept coming after them, and Mark Clayton showed what a great big-play receiver he is."

With 2:38 left in the game, Marino threw a 38-yard pass to Clayton and gave the Dolphins a 21-14 lead.

The Cowboys struck back quickly. Quarterback Danny White, who played exceptionally well in the second half to finish with 20 completions in 34 passes for 246 yards, needed only two plays to overcome the deficit. He passed to Tony Hill on the far sideline, and Hill pulled in the tipped ball and ran untouched down the sideline for 66 yards and the touchdown. There was only 1:47 on the clock, and the score was tied, 21-21.

After Miami's vehement protest that Hill was out of bounds when he made the catch, the officials ruled that the ball was tipped and Hill had come back in to catch it properly. That set the stage for the ensuing drama, which made the price of admission seem cheaper than a free lunch.

Marino came back with miraculous fervor and passed 63 yards to Clayton, who crossed the goal line with 51 seconds left. Uwe Von Schamann's extra point put the Dolphins ahead, 28-21. "That play was called 70 Texas," Marino said. "Mark sure has a knack of getting open. He's a big-play guy, and I'm very fortunate to have guys like him and Mark Duper on my team."

It was Clayton's third touchdown reception and gave the second-year man from Louisville 18 touchdown receptions this season, breaking the record of 17 set by Don Hutson, Elroy Hirsch and Bill Groman. Most important, though, it closed the book on this hard-fought game.

The first quarter proved a defensive struggle, with neither team seriously threatening. As if to break the boredom, Marino, passing to Clayton, was intercepted by cornerback Ron Fellows, who returned to the Miami 43.

White passed to Hill for 11 yards, then Timmy Newsome gained five off left tackle. The Cowboys were able to move down to the Dolphins' 22 but blew their chance when cornerback William Judson picked off White's weak pass toward Newsome in the end zone.

Marino opened the ensuing drive with a 14-yard pass to tight end Bruce Hardy. Shortly after the running game pushed Miami into the Cowboys' territory, defensive tackle Randy White sacked Marino for a 12-yard loss, but that did little to kill the Dolphins' momentum. On the next play, rookie Joe Carter got the 12 yards back on a power sweep off the left corner.

The drive extended into the early moments of the second quarter, but ended when Nat Moore was stripped of a pass reception and Fellows recovered for the Cowboys. After returning the ball six yards, Fellows fumbled but teammate Victor Scott pulled in the dribble at the Dallas 40.

Miami was better on its next drive, going 80 yards in eight plays for the only score of the first half. It started when Marino passed 22 yards to Moore over the middle. That pass was more than enough for Marino to break Dan Fouts' single-season passing-yardage record of 4,802, set in 1981 with the San Diego Chargers.

Marino finished with 340 yards tonight, giving him 5,084 this season. The play stopped momentarily as the officials gave Marino the ball, and one can only imagine what the second-year quarterback told his teammates when he returned to the huddle. He probably said, "Forget the record; let's go to work," because that is exactly what the Dolphins did.

A key penalty pushed the Dolphins deeper into Dallas territory. Strong safety Bill Bates, screaming in on the blitz, roughed Marino. Two plays later, Marino passed to Clayton, who used Moore's big block to find the end zone.