Spurred by what could be an unprecedented discovery, Utah paleontologists continued their efforts Thursday to salvage the skeletal remains of a huge prehistoric mammoth found near Huntington Reservoir.

Scientists say the discovery of a mammoth at such a high elevation could force a fundamental rethinking of commonly held theories about the mammoth's lifestyle and habitat.When scientists started excavating at the 9,000-foot elevation, they assumed they were digging up a prehistoric mastodon - a tree-eating herbivore common to higher elevations.

But once they got to the animal's skull, they discovered not a mastodon, but a mammoth - a grass-eating contemporary of the mastodon never before found above 7,200 feet.

"It was something of a surprise," said David Gillette, the state paleontologist. It is unusual, he said, because "high altitudes were thought to be unsuitable."

Scientists say the difference between mammoths and mastodons is their teeth. The larger mastodons have "chomping teeth" designed for eating foliage and trees, which make them better suited for the the forests at higher elevations.

Mammoths, which have grinding teeth for eating grasses, were thought to have been plains animals. Now scientists are scratching their heads over how a plains animal made it to the mountains.

Crews from Nielsen Construction, working on a new irrigation dam, had been clearing a boggy area on U.S. Forest Service land when a backhoe operator dug up a piece of tusk and a humerus bone.

That was Monday afternoon, and by 1 p.m. Tuesday state scientists had converged on the rare find. The removal is expected to take several more days, even with the assistance of dozens of volunteers from the local area.

Gillette, a specialist in Pleistocene vertebrates, speculates the mammoth probably lived in the area next to the stream. The condition of the huge skeleton indicates it has not moved far from where the creature died, and its discovery in the bog may indicate he became trapped.

The mammoth probably lived 10,000 to 15,000 years ago, Gillette said.

The bones are "as fresh as modern bone," though darkened with time, said Gillette. "We're taking it out bone-by-bone."

The bones are being removed to the College of Eastern Utah where they are being dried under controlled conditions. Then they will be transported to Gillette's laboratories in Salt Lake City.

Final ownership of the mammoth skeleton, however, has yet to be determined. The Forest Service owns the skeleton because it was found on Forest Service lands. But Gillette is hopeful the state can negotiate with the federal government to acquire it.

The mammoth as a species is believed to have originated on the North American continent. It had curved tusks and a huge, elephant-like body weighing several tons. (Not all mammoths were hairy.)

Mammoth remains have been discovered all over the world, including Utah.