Jurassic Park

Still, the dinosaurs had appeared at an unusual time in his life. For having built himself a mountain paradise, he was already thinking of selling it, an impulse which persists today, even though he can't, or won't, explain it very well.

"I've never been a really active seller," Cook said, but he speaks of downsizing, of finding a suitable buyer so as not to saddle his son, Gabe, with "such an immense responsibility." His daughter is in medical school.

"You can be the best operator in the world and go broke," Cook said. "It wouldn't even be your fault."

But "suitable" is a daunting condition for Cook. He would prefer to sell to another cattleman like himself, he said, but grassland in Wyoming had become so expensive by 1999 that no real rancher could afford to buy the whole spread and operate it at a profit. He would also sell to an "amenity rancher," a hugely rich person with a yen for the Western life, as long as the integrity of the property was maintained.

But under no terms would he sell to a developer, who might build a speedway on the property or divide it into 400-acre vacation "ranchettes."

Cook doesn't talk much about why he was, and is, so choosy, perhaps too choosy to ever sell the ranch. But he has tremendous respect for his land, not only for itself but because of how he has restored and maintained it. Cook can recount more than 100 years of his ranch's history, from Swan to himself, a continuum of private ownership and personal responsibility that has left the land almost as elegantly unbesmirched as the day the first Native American saw it, perhaps 12,000 years ago. He wants to continue the tradition. No picnic tables, no garbage cans, no campgrounds, no beer bottles, no hiking trails, no candy wrappers, no motocross. Never.

Cook developed a plan. He would seek a "conservation buyer," a nonprofit organization that would take care of the property, and use Spring Creek as a sweetener. The buyer would pay a premium for the dinosaur piece, then donate it to a university and take a tax deduction.

He opened negotiations with the Wyoming chapter of the Nature Conservancy, and at the same time he hired Bill Mundy, a Seattle-based real estate appraiser who specializes in putting dollar values on land with archaeological or earth science potential. Mundy had appraised Utah's Dinosaur National Monument, California's redwoods and 1.7 million acres of old growth forest on Tierra del Fuego.

Mundy visited Spring Creek in 2000 and saw the dinosaur bones and the Native American sites. "The ranch was just gargantuan," Mundy recalled. "I told Allen, 'In my opinion you don't have a ranch, you have a natural science laboratory.' And besides that, there's this huge history in the region."

Which might make the property even more attractive. Besides its history of Tom Horn and the Swan ranch, Spring Creek is next door to what is left of Wilcox, Wyo., where Butch Cassidy and the Sundance Kid robbed the Union Pacific, triggering the manhunt that eventually forced them to flee to Bolivia.

The Union Pacific still whistles past the Cook ranch today on the original track bed of the transcontinental railroad, barreling through cities and towns known to generations of Western history buffs -- Cheyenne, Laramie, Wilcox and Medicine Bow, the setting for Owen Wister's 1902 novel, The Virginian, whose laconic hero was the central character in two movies and a TV show.

Mundy appraised Spring Creek at $8 million and offered a suggestion. His boyhood friend Alec Stewart served as dean of the University of Pittsburgh's Honors College, which might be interested in buying Spring Creek. The Honors College ran a student summer camp outside Yellowstone Park to study natural science. Mundy telephoned Stewart in the autumn of 2000 and told him how "you stumble all over the dinosaurs" at Spring Creek and how it was "a national treasure. What better way to oversee it than to associate it with a university?"