If The Who, Britain’s grand masters of megaton rock, are to be considered one of today’s musical “dinosaurs,” then the capacity crowd at Alpine Valley for Friday’s concert was an archaeological gold mine.

In the sea of some 40,000 faces, few appeared younger than 25 years old. Attire was upscale casual. Torn jeans were rare, and most of the T-shirts visible were purchased that night.

These were the people you usually see working at your bank or managing a retail store, and quite likely the parents of at least one teenager.

This was also the audience that set an all-time speed record for ticket sales at the outdoor theater to be present for the first of three consecutive shows by a band known more for its force than finesse.

Handsomely middle-aged, guitarist Pete Townshend bounded on-stage first to the taped theme from the TV series “Bonanza,” followed by radiantly fit singer Roger Daltrey, sartorially splendid bassist John Entwistle and drum demon Simon Phillips.

The rest of the entourage — a guitarist and keyboardist, two percussionists, three back-up singers, four horn players — took their places swiftly and before the clamor that greeted them could subside, the band launched into the Overture from the famed rock opera, “Tommy.”

Townshend, suffering from a painful hearing malady called tinnitus, played an acoustic guitar instead of the more appropriate electric tool. Scotsman Steve “Boltz” Bolton handled the lead guitar role admirably while Townshend unleashed the most powerful “folk” guitar parts ever heard.

Phillips’ drumming was astounding — wild in the tradition of Who original Keith Moon and dynamic enough to turn from deafening thunder to a whisper of cymbals in a heartbeat.

The Who: Still big and bouncy, if a bit grayer, after 25 years playing together.

Obviously looking older after 25 years together, the Who alumni appeared no less enthusiastic about performing tunes they’ve done a thousand times before.

Classic cuts like “Pinball Wizard” had the audience in ecstasy, especially with full-bodied brass and keyboard reinforcement.

In the half-hour condensed version of “Tommy,” The Who displayed rock at its most arrogant, underscored by the lines, “We’re not gonna take it. Never did and never will.”

During “See Me, Feel Me, Touch Me, Heal Me,” thousands of lighters glowed in the darkness. From the stage, it must have looked like some sort of religious rite.

The songlist then shifted to contemporary material like Townshend’s newest single, “A Friend Is A Friend.”

Before that segment, however, the lanky guitarist known for his leaps and windmill strumming style explained his aural problem. He joked about being on medication and not knowing how it would affect his playing. He also claimed, jokingly, that his acrobatic guitar style had somehow disconnected his brain.

With a serious tone, he revealed that singing and just being around loud music caused him severe pain.

“But that doesn’t mean I’m not happy to be here,” he stated. After a brief pause for applause he said softly, “I’m very happy to be here.”

The rest of the first 90-minute set ranged from the band’s earliest cover material, like Muddy Waters’ “I’m A Man,” to their own classics “I Can’t Explain” the explosive “I Can See For Miles” and humorous “Boris The Spider” (during which Townshend played hard enough to snap a string).

As if caught up in his own Whon-ess, the man who said he wouldn’t “windmill” did just that repeatedly. The man who said he wouldn’t leap around did a lot of that, too. And harkening back to the days when equipment trashing was their grand finale,

Townshend struggled with a guitar strap that came loose twice before flinging the offending instrument to the stage and kicking it.

The 17-minute intermission was the only time the crowd used the seats to sit. Everyone was seemingly catapulted erect again when Part Two opened with “Magic Bus” and its more pronounced Bo Diddley rhythm.

With the large band, Daltrey had plenty of vocal support for the high ranges he had difficulty reaching. Musically, the effect was like Benny Goodman’s big band meets heavy metal.

“Love Reign O’er Me,” from the concept work “Quadrophenia,” was absolutely majestic, largely due to the keyboard wizardry of John “Rabbit” Bundrick.

Decades ago, a rock “fanzine” used the headline, “Nobody is allowed to die until The Who have stopped playing.”

When this tour is over, they deserve to rest in peace.