Using tiny brushes and chisels, workers picking at a big greenish-black rock in the basement of North Dakota's state museum in Bismarck are meticulously uncovering something amazing: a nearly complete dinosaur, skin and all.

Unlike almost every other dinosaur fossil ever found, the Edmontosaurus named Dakota, a duckbilled dinosaur unearthed in southwestern North Dakota in 2004, is covered by fossilized skin that is hard as iron. It's among just a few "mummified" dinosaurs in the world, say the researchers who are slowly freeing it from a 65-million-year-old rock tomb.

Stephen Begin uses an air tool to chip away at sandstone surrounding a dinosaur mummy at the North Dakota Heritage Center Museum in Bismarck, N.D., on Feb. 27.
(Will Kincaid/Associated Press)

"This is the closest many people will ever get to seeing what large parts of a dinosaur actually looked like, in the flesh," said Phillip Manning, a paleontologist at Manchester University in England, a member of the international team researching Dakota.

"This is not the usual disjointed sentence or fragment of a word that the fossil records offer up as evidence of past life. This is a full chapter."

Animal tissue typically decomposes quickly after death. Researchers say Dakota must have been buried rapidly and in just the right environment for the skin to be preserved.

"The process of decay was overtaken by that of fossilization, preserving many of the soft-tissue structures," Manning said.

Dakota remains a special find

Tyler Lyson, a 25-year-old doctoral paleontology student at Yale University, discovered the dinosaur on his uncle's ranch in the Badlands in 1999. Weeks after he started to unearth the fossil in 2004, he knew he had found something special.

"Usually all we have is bones," Lyson said in a telephone interview. "In this special case, we're not just after the bones; we're after the whole carcass."

Researchers have used the world's largest CT scanner, operated by the Boeing Co. in California and used to examine space shuttle parts, to get a better look at what is encased in the rumpled mass of sandstone.

"This is the fourth dinosaur mummy that's ever been found in the world of any significance," said Stephen Begin, a Michigan consultant on the project. "It may turn out to be one of the best mummies, because of the quality of the skin that we're finding and the extent of the skin that's on the specimen."

Dakota was moved to the museum early last month and is currently surrounded by precariously perched desk lamps and a machine to suck up dust. State paleontologist John Hoganson, of the North Dakota Geological Survey, said it will take a year, maybe more, to uncover it.

Long hours needed to uncover fossil

Amy Sakariassen, part of the team working on the project, was toiling away with a brush whose bristles had been ground down to nubs.

"It really is wonderful to work on it," she said, as Begin used a sharp instrument to pick away tiny bits of rock and unveil a scale. "Nobody's seen that particular scale in 67 million years. It's quite thrilling."

Manning said his involvement has meant 18-hour days, seven-day weeks and "more work than I could have ever imagined. But I would not change a single second of the past few years."

Hoganson said the main part of the fossil is in two parts, weighing a total of nearly 4.5 tonnes.

"The skeleton itself is kind of curled up," he said. "The actual length would be about 30 feet (nine metres), from about the tip of its tail to the tip of its nose."

The fossil has spawned both a children's book and an adult book, as well as National Geographic television programs. The National Geographic Society is funding much of the research.