Scientists today announced the discovery of an extraordinarily preserved "dinosaur mummy" with much of its tissues and bones still encased in an uncollapsed envelope of skin.

Preliminary studies of the 67-million-year-old hadrosaur, named Dakota, are already altering theories of what the ancient creatures' skin looked like and how quickly they moved, project researchers say.

Further investigations may reveal detailed information about soft tissues, which could help unlock secrets about the evolution of dinosaurs and their descendents, the scientists added.

For now, the team continues to examine the rare specimen, which included preserved tendons and ligaments, and to prepare scientific articles on the find for publication.

"This specimen exceeds the jackpot," said excavation leader Phillip Manning, a paleontologist at Britain's University of Manchester and a National Geographic Expeditions Council grantee.

Most dinosaurs are known only from their bones, which are seldom found joined together as they would be in real life.

But "we're looking at a three-dimensional skin envelope," Manning said. "In many places it's complete and intact—around the tail, arms, and legs and part of the body."

(The excavation is the subject of Dino Autopsy, a National Geographic Channel special airing December 9 at 9 p.m. ET/10 p.m. PT. The National Geographic Society owns National Geographic News and co-owns the National Geographic Channel.)

Find of a Lifetime

The hadrosaur, or duck-billed dinosaur, was discovered in 1999 by then-teenage paleontologist Tyler Lyson on his family's North Dakota property.

It was an extremely fortuitous find, because the odds of mummification are slim, researchers noted.

First the dinosaur body had to escape predators, scavengers, and degradation by weather and water. Then a chemical process must have mineralized the tissue before bacteria ate it. And finally, the remains had to survive millions of years undamaged.

"What usually would have been wiped out by the decay process—the mineralization has been so rapid that it is trapped and preserved," Manning said.

"It's such a unique preservational environment here that we'll be able to say, Well, you basically need these conditions to mummify a dinosaur," Lyson, now a graduate student in geology at Yale University in New Haven, Connecticut, told a National Geographic reporter during a field trip to the excavation site.

"I think that's going to be pretty neat."

Big Rear, Fast Runner

Plant-eating hadrosaurs are often called the "cows of the Cretaceous"—the geologic period that spanned 145 million to 65 million years ago—Manning said. They had horny, toothless beaks but hundreds of teeth in their cheeks and a long, stiff tail that was likely used for balance.

Preliminary studies are revealing a surprising side to these reptiles, suggesting that Dakota—even though roughly 35 feet (12 meters) long and weighing some 3.5 tons—was no slowpoke.

With the aid of a large-scale CT scanner, the researchers determined how much muscle mass was packed between the bone and skin of Dakota's tail.

This allowed the researchers to infer the muscle mass of the dinosaur's rear end, which they calculated is about 25 percent larger than previously believed. A more muscular rear end means more powerful legs, Manning noted.

He plugged this new measurement into a computer model his team created to figure out how dinosaurs moved.

"Our models confirm this hadrosaur would have had potential to run faster than T. rex," Manning said.

The preliminary calculations suggest Dakota could run 28 miles (45 kilometers) an hour. Tyrannosaurus rex tops out at about 20 miles (32 kilometers) an hour, according to the model.

For Manning, the finding makes perfect sense. Hadrosaurs are believed to have been T. rex prey, so evolution would have favored a faster running speed.

"And that's what our initial findings support," he said.

John Hutchinson studies the movement of living and extinct animals at the University of London's Royal Veterinary College. He said caution is warranted for claims based on computer simulations, which he uses for his own work.

The margin of error for locomotion computer models can be greater than 50 percent, he noted—enough to wipe out the speed difference between a hadrosaur and a T. rex.

"Knowing the leg muscle mass would reduce at least one uncertainty," he commented via email. "That's progress, but there are still huge uncertainties left."

Showing Some Skin

Research into Dakota's fossilized skin is also yielding image-altering clues to how hadrosaurs may have appeared, Manning's team says.

Though the skin has lost its color, much of its texture is still intact, allowing scientists to map it in 3-D to see what Dakota might have looked like.

"There seems to be a variation in scale size that might possibly correlate—as it does in modern reptiles in many cases—with changes in color," Manning said.

"There seems to be striping patternations associated with joint areas on the arm," he added, "and there's interesting information we're looking at in the tail as well."

The 3-D preservation of the skin has also prompted the researchers to search for traces of unfossilized soft tissue in the hopes that it might yield protein.

This April, for example, two teams announced the successful extraction and analysis of collagen, a bone protein, from 68-million-year-old T. rex fossils. Those findings supported the hypothesis that modern birds are descended from dinosaurs.

Manning's team is currently unable to discuss specific findings, which are pending peer review for publication in a scientific journal.

But team member Roy Wogelius, a geochemist at the University of Manchester, said: "We have an array of chemical analysis techniques that we're applying to the organism—and not just to the skin."

Remains to Be Seen

Other experts remain tight-lipped about the potential of Dakota to yield similar information as the T. rex studies.

Mary Schweitzer, a North Carolina State University scientist who worked on one of those projects, declined to comment until formal publication.

And Peggy Ostrom, a zoologist at Michigan State University who also studies ancient proteins for clues to how organisms are related to each other, commented only in general terms.

"It's rare to find an articulated skeleton and even more so to find one with fossilized soft tissue," she wrote in an email.

"If such finds show extraordinary preservation, they tempt us to wonder about the possibility of finding [unfossilized] biomolecules that might be remnants of the ancient organism."