The Dallas Cowboys sprang a memorable Bear trap today. They held Walter Payton to mortal yardage, and they did it with a defense led by Pat Donovan and John Fitzegerald, Roger Staubach, Tony Dorsett and . . .

Yes, I know those guys line up on offense. But today they had more to do with the Cowboys rendering Payton and the Chicago Bears harmless than all the tacklers in Texas.

Payton, splendid runner that he is, cannot gain yardage sitting on the bench - and that is where the Dallas offense kept him until this first-round National Conference playoff was decided - half time.

In the first 20 minutes, Payton carried the ball seven times for 18 yards. By that time the Cowboys ran nearly twice as many plays as the Bears, gained three times as many yards and took a 17-0 lead that could have been much more except for two fumbles.

"It's as well as we've ever played in a big game," quarterback Staubach admitted. "A lot of it was the game plan, and we ran things out there at times like you draw 'em up."

Not that the defense took the day off. Hardly. It did exactly what coach Tom Landry expects it to do against the Paytons of the world. Or as Thomas Henderson put it so well: "We gapped his ass."

That is about as eloquent as anyone can get in explaining the flex defense in four words or less. Naturally, Henderson volunteered to be more expansive.

"What happens is the ends contain and everyone fills a gap," he said. "Everyone holds his position - and when that happens a man can't go anywhere but down."

In truth, the Cowboys were not quite as effective against the NFL's most productive runner as they were here last season. In that game, Payton gained only 41 yards in 17 carries: today he mustered 60 yards in 19 carries, but most ofthat came after Dallas was assured victory.

And that happened because Staubach was exceptionally sharp and blockers such as center Fitzgerald and Donovan opened holes Mother Tums could trot through unmolested.

It was such a splendid combination of offense and defense that one could spend time lamenting a particularly awful performance from a group of superstars that ordinarily might have stolen the show.

To country and western music fans, there is no more delightful lineup of players than Waylon Jennings, Jerry Jeff Walker, Johnny Rodriguez, Hank Williams Jr. and Alex Harvey. Except when they combine on something called "Jingle Spurs," which Cowboy management played as the game was becoming a rout.

It includes:

"Santa Claus was here

With tons of Christmas cheer

He stayed to watch the Cowboys run

Right past his own reindeer .

The world makes such a fuss

When the Cowgirls cheer for us

And Big D's riding high with prides

'Cause the Cowboys ride for us .

Jingle Spurs, Jingle Spurs ,

Cowboys all the way ,

Oh what fun it is to win

The playoff game today."

There was a tear in the eye of Texas after the final refrain - and C & W fans admitted lyrics like that had not come forth since "Lookin' through the knothole of Daddy's wooden leg."

The Cowboys' music was sweet, though, and the major reason was Dorsett. Let Donovan explain:

"He's at the hole while we're working our blocks, just making contact," he said. "While the defensive man is trying to figure out what to do, Tony's already in the hole.

"He makes some awful blocks look good, because he'd by 'em right quick. And when you see the guy you've got to block look over your shoulder (to Dorsett), that's nice.

"It takes the pressure off all of us - off Roger, off Drew Pearson, every one of us."

Left tackle Ralph Neenly was not quite so charitable:

"Well, they were 12th in offense in a division not known for its offense," he said. "No, that's not saying a whole lot."

But it's more than Waylon and his minstrels could say.