One of the holes dug by Larry Walker, a self-taught fossil hunter who stumbled across the remains of a previously-undiscovered dinosaur in the desert south of Green River.

GREEN RIVER - Grain by grain, pebble by pebble, Larry Walker's X-Acto knife chipped away at the soft mudstone rock face.

Under cover of darkness, he hunched in his tiny tunnel the width of a sidewalk. The krypton bulb of his headlamp cast a circle of light on the gray rocks as the former uranium miner slowly extracted bits of another rare find - dinosaur fossils.

The femurs, ribs and other bones came loose in a jumble, rarely intact.

Walker, self-taught in the science of dinosaurs, puzzled over the neck vertebra. Long and grooved along the bottom, they matched nothing in his books.

As he turned the bones over in his hands, he suspected he had stumbled on something new.

His suspicion proved right, but it would be years before Walker revealed what he knew. The dinosaur he surreptitiously dug from the Earth represented an unprecedented glimpse at a dinosaur family caught evolving from meat eaters to plant munchers that would garner Utah international attention.

Like a boy eyeing his first dinosaur skeleton at a museum, he was obsessed with the fossils. He knew every bit of dinosaur bone he pulled from this patch of federal land broke the law, yet he kept going.

Walker desperately wanted to research this find - his dinosaur - alone, yet doubts crept into his head during his 12-hour shifts deep in the desert.

Giving up his dinosaur, though, carried grave consequences. The longer he kept the find a secret, the more his obsession grew.

Raised in Moab, Walker hunted, fished and rockhounded in southern Utah's badlands. Like others in the area, he developed the attitude that federal control of the land he loved did little other than keep people from making a living.

Walker still managed to find ways to profit from the places he played as a child - mining, logging and scouting locations for ads. A high-school dropout at 17, he jumped from job to job.

In his spare time, he trekked into the Mars-like terrain in search of agate, a multicolored variety of quartz. He transformed bits of red, black, blue and tan into jewelry to sell.

On a gusty day in 1997 while hunting for rare Yellowcat Redwood agate, Walker came across a smattering of fossilized gizzard stones. Among them, he spotted a single, gray toe bone.

"The fossil was so perfect, it still had the small vein and artery openings in the bone and all the little muscle attachment features on the bone," he recalled.

The find launched a three-year clandestine mining operation. A week after finding the toe bone on the canyon floor, he returned to discover more bones at the top of a nearby plateau. Each morning, he hiked about a mile to his site, rotating through one of five different trails to avoid leaving a worn path.

Temperatures often topped 100 degrees as he climbed into his 4-foot-high tunnel shaft.

Wearing faded Levi's that he found forgiving under the desert sun, he worked 10- to 12-hour shifts, digging tunnels deep enough to shade his upper body.

Lying on his side, he scraped away at the mudstone, removing a cubic foot of material in a shift. He wrapped the bones in paper towels and placed them in plastic bags. Any bones he deemed unworthy of reconstruction, he tossed into a nearby trash pile.

Periodically, Walker swept the tunnel floor clean so he could see any bone that fell from the ceiling. To prevent cave-ins, he removed the overhanging material every few feet.

Paleontologists cringe at this tunneling technique. Professionals dig from above so they can map and photograph each bone where it was found to better understand the context of the find.

Walker cared little about context. He simply wanted enough bones for a skeleton of the beast.

The work was grueling. In three years, he spent up to 900 hours working in five different shafts.

With little money to support himself, he fretted over each tank of gas for his old Chevy truck to carry him from Moab to the site south of Green River. He slept under a camper shell night after night to save money.

Though he dug in a desolate area for days at a time, the fear of being detected haunted Walker.

He walked on sandstone outcroppings whenever possible to reduce footprints. He planted fossilized wood chunks near his mini-mining shafts, hoping unexpected visitors might assume the holes contained wood, not bones.

"I knew if I was discovered by federal agents, it would be taken away from me," he said. "I was torn between 'I know this is against the law - I don't know why it is, but I know it is' - and my curiosity to know what happened here. I was never afraid I would destroy anything. It's not my nature. I'm a preservationist."

As much as the law concerned him, other prospectors worried him more.

"I was very protective of that site," he said. "It was my baby."

Planes passing overhead on the Moab-Green River route provided yet more aggravation, since a curious pilot might spot his operation. Walker worked under canvas tarps at times, but those covers trapped the heat.

"In the summer, the temperatures got to be unbearable," he said. "It got to the point where it hurt me so much I had to start changing my procedures and work at night."

The cooler temperatures helped, but he could no longer camp in his truck, which became an oven during the day. He started commuting from Moab.

At the end of each outing, Walker hauled his take back to a Moab house he shared. In a spare bedroom where he made jewelry, he set aside a table for the bones.

Using Paleo-Bond, a specialized glue available at fossil shows, he rebuilt each bone like he was solving a jigsaw puzzle. Walker, whose formal education ended once he obtained a general high school equivalency diploma, consulted books - including The Dinosaur Heresies by Robert Bakker and Principles of Geomorphology - to learn all he could about his critter.

He thought his dinosaur might be Deinonychus, a small meat-eating dinosaur with sharp claws, or Utahraptor, another fierce predator.

Curiosity drove him to learn about what he found. But Walker needed cash to help support himself as he pursued this dinosaur mystery.

Hanging out in the parking lots of an Arizona gem and mineral show, he peddled his "extra" bones to passers-by. He lied to potential buyers, saying he had Utahraptor fossils found on a private ranch near Blanding.

The enterprise marked the beginning of his downfall.

glavine@sltrib.com

UP NEXT:

Monday: Dinosaur bones on the black market

Tuesday: The paleontologists

Wednesday: A secret meeting in the desert