The Dakota dinosaur story that is tearing up the newswires is not, in fact, about the Dakota dinosaur museum. It’s actually about something much more interesting that that. For what, in thi sense at least, "Dakota dinosaur" refers to is a mummified remains: that is, it’s isn’t purely a bone fossil, there’s actually evidence of muscle there (which, being 65 million years old is of course fossilised):

The world of 65 million years ago is filled with mystery, especially because scientists have little to go on but bones.

But buried in a remote corner of North Dakota was a remarkably
well-preserved dinosaur with fossilized skin, ligaments and tendons.
You can even see scales on its side.

…

Tyler Lyson, the young scientist who found the fossil, said, "The skin
hadn’t collapsed in around the bone, and at that point I knew that we
had a 3-D dinosaur mummy. I was absolutely thrilled."

Lyson is currently pursuing his doctorate in paleontology at
Yale University and founded the Marmarth Research Foundation, an
organization dedicated to the excavation, preservation and study of
dinosaurs.

Why
is it important to find one so complete? Because bones don’t tell you
what the animal really looked like. Imagine if you found elephant
bones, but you’d never seen a living one.

Well, quite, how would you rebuild an elephant only from the bones? We can look around at other animals, work out how bones relate to other parts, but we’re always making estimates and judgements, rather than actually being certain:

Specifically, the discovery is expected to add an extraordinary amount
of information about how such animals looked inside and out. It is
expected that the discovery will add to human knowledge on how
dinosaurs evolved over time.

The soft muscle, ligaments, tendons, and skin from a 25-foot (7.6
meter) hadrosaur (or duck-billed dinosaur, because their heads look
similar to ducks) was found in 1999 by 16-year-old Tyler Lyson
on his uncle’s ranch in the Hell Creek Formation Badlands of North
Dakota. Lyson now goes to school at Yales’ Department of Geology and
Geophysics in New Haven, Connecticut.

Much of the discovered bodily material is from the animal’s arms, legs, and tail.

Lyson’s discovery was reported by scientists on Monday, December 3,
2007 and is already considered a major find of a well-preserved
specimen of a dinosaur. Scientists consider this discovery to be the
first-ever of a dinosaur with its skin envelope not collapsed onto the
sheleton. The specimen has been nicknamed “Dakota,” and is estimated to
be about 67 million years old.

As to how the Dakota dinosaur was actually found, well, let the boys from Dakota talk about one of their own:

The story of Dakota, the dinosaur “mummy,” is big news
in dinosaur circles, and for good reason: The fossilized hadrosaur is
the find of the century.

But the dinosaur’s tale ought to be big news in North Dakota, too – and not just because the fossil was discovered here.

No, Dakota’s story is a North Dakota gem because of how the great beast
was discovered – and by whom. The “how” is that an amateur dinosaur
hunter used some good paleontology field work to find the fossil in the
Badlands in 1999.

…

“On an expedition in 1999, Lyson noticed some bone fragments at the
base of a hill and traced their origin to a point farther up. There he
spotted three vertebrae from the tail of a hadrosaur, a common plant
eater that traveled in herds and is sometimes described as the cow of
the Cretaceous Period.”

Lyson himself dismissed the find at first; dinosaur fossils are common in the area, called the Hell Creek Formation.

“After finding a small piece of fossilized skin, however, Lyson knew he was onto something special,” the Post reported.