WASHINGTON — One of the most complete dinosaur mummies ever found is uncovering secrets locked away for millions of years, bringing researchers as close as they will ever get to touching a live dino.

The fossilized duck-billed hadrosaur is so well preserved that scientists have been able to calculate its muscle mass and learn that it was more muscular than thought, probably giving it the ability to outrun predators such as T. rex.

While they call it a mummy, the dinosaur is not really preserved like King Tut was. The dinosaur body has been fossilized into stone. Unlike the collections of bones found in museums, this hadrosaur came complete with skin, ligaments, tendons, and possibly some internal organs, according to researchers.

The study is not yet complete, but scientists have concluded that hadrosaurs were bigger and stronger than had been known, were quick and flexible, and had skin with scales that may have been striped.

“Oh, the skin is wonderful,” paleontologist Phillip Manning of Manchester University in England rhapsodized, acknowledging a “glazed look in my eye.”

“It’s unbelievable when you look at it for the first time,” he said in a telephone interview. “There is depth and structure to the skin. The level of detail expressed in the skin is just breathtaking.”

Mr. Manning said a pattern of banding is evident in the larger and smaller scales on the skin. Because it has been fossilized, researchers do not know the skin color. Looking at it in monochrome shows a striped pattern. He notes that in modern reptiles, such a pattern is often associated with color change.

The fossil was found in 1999 in North Dakota and now is nicknamed “Dakota.” It is being analyzed in the world’s largest CT scanner, operated by the Boeing Co. The machine usually is used for space shuttle engines and other large objects. Researchers hope the technology will help them learn more about the fossilized insides of the creature.

“It’s a definite case of watch this space,” Mr. Manning said. “We are trying to be very conservative, very careful.”

But they have learned enough so far to produce two books and a television program. The TV special, “Dino Autopsy,” will air on the National Geographic channel December 9. National Geographic Society partly funded the research.

A children’s book, “DinoMummy: The Life, Death, and Discovery of Dakota, a Dinosaur From Hell Creek,” goes on sale tomorrow and an adult book, “Grave Secrets of Dinosaurs: Soft Tissues and Hard Science,” will be available in January.

Soft parts of dead animals normally decompose rapidly after death. Because of chemical conditions where this animal died, fossilization — replacement of tissues by minerals — took place faster than the decomposition, leaving mineralized portions of the tissue. That does not mean DNA, the building blocks of life, can be recovered, Mr. Manning said. Some has been recovered from frozen mammoths up to 1 million years old, he said. At the age of this dinosaur, 65 million to 67 million years old, “the chance of finding DNA is remote,” he said.

A Manchester colleague, Roy Wogelius, who also worked on the dinosaur, said, “One thing that we are very confident of is that we do have some organic molecular breakdown products present.” That look at chemicals associated with the animal is still research in progress.

Matthew Carrano, a paleontologist at the Smithsonian’s National Museum of Natural History, said he could not comment in detail about the find because he had not seen the research. But, he added, “Any time we can get a glimpse of the soft anatomy of a dinosaur, that’s significant.”

The findings from Dakota may cause museums to rethink their dinosaur displays.

Most dinosaur skeletons in museums, for example, show the vertebrae right next to one another. The researchers looking at Dakota found a gap of about a centimeter — about 0.4 inch — between each one. That indicates there may have been a disk or other material between them, allowing more flexibility and meaning the animal was actually longer than what is shown in a museum. On large animals, adding the space could make them a yard longer or more, Mr. Manning said.

Because ligaments and tendons were preserved, as well as other parts of Dakota, researchers could to calculate its muscle mass, showing it was stronger and potentially faster than had been known. They estimated the hadrosaur’s top speed at about 28 miles a hour, 10 mph faster than the giant T. Rex is thought to have been able to run.