Sometimes the delicate tools of dinosaur diggers just don't cut it.

Thwarted since 2007 by layers of rock-hard sandstone, researchers at one of Dinosaur National Monument's most important quarries turned to something more potent than brushes and hammers: explosives.

Crews set off a series of blasts earlier this month at a quarry known as DNM 16. It's the same site that several years ago yielded a complete sauropod skull, one of the rarest finds in the dinosaur business.

Tantalized by that discovery and other less-complete skulls, researchers were determined to find out what else was hidden in the quarry.

The problem, though, is that the rock around the bones is so hard that workers had been unable to break through, even with use of a jackhammer, said Dan Chure, a paleontologist at the monument that straddles the Utah-Colorado border.

That's why they sought out the blasting crew from Rocky Mountain National Park that typically uses explosives for work on trails, roads, utility lines and parking lots.

"There was no other way for us to get to these bones other than using these explosives," he said.

The work was unusual but not unprecedented. A similar operation was conducted at a nearby fossil quarry about 12 years ago.

This time around, the blast team spent three days at the monument detonating handset explosive charges to clear away the sandstone. It was a delicate operation using enough explosive power to get the job done but not so much it would ruin the bones that paleontologists are after.

Over three days, the team dug about 40 bore holes to drop explosives inside. After the blasts, much of the material could be moved by hand.

Chure said he didn't see any sign of damage to the dinosaur bones.

Digging at the site is expected to resume this spring.

In 2005, researchers from Brigham Young University and the monument announced the discovery of the skull of a sauropod, a hulking plant-eating dinosaur with a relatively small head. The complete skull from the Lower Cretaceous period is the only known one in North America from the final 80 million years of dinosaurs' reign.

Sauropods were a group of long-necked, long-tailed dinosaurs often considered the biggest beasts ever to walk on land.