Dino-mummy: in the flesh. (Life/Earth News).

For a paleontologist (fossil scientist), nothing beats digging up dinosaur bones--except when the bones are still covered in skin! "The odds of finding dino skin are way out there," says paleontologist Nate Murphy at the Judith River Dinosaur Institute in Montana. Last summer, Murphy and his team unearthed a 7 meter (23 foot)-long fossil of a hadrosaur (duckbilled dinosaur). To Murphy's amazement, its bones were sheathed in rock-hard skin, muscles, even fingernails. The 2-ton dino-mummy--nicknamed Leonardo--is only the fourth dino fossil in history to be found with such well-preserved tissue.

Murphy's team discovered the 77-million-year-old Brachylophosaurus (duckbilled species) buried beneath 3.5 tons of sandstone in a dried-up riverbed in northern Montana (see map, above). Normally, living tissue such as skin rots from a carcass as it biodegrades, or decays. But Leo's tissue was preserved, or mummified, before it was fossilized because he died in a pool of wet river sand. Leo's body turned to stone as calcium carbonate, a mineral compound found in bones, as well as sandy water, leached into the decaying carcass. Over time, the tissue slowly calcified (hardened), much like bones do as they are formed.

So what new secrets can Leo reveal about the lives of extinct reptiles? One big clue, says Murphy: The right shoulder muscle is larger than expected--which implies hadrosaurs may have been quadripeds (four-legged walkers), not bipeds as originally suspected. Murphy was also surprised to find a thick neck and a fleshy rooster-like frill along the length of the back, features never before observed--not even in Jurassic Park. "Steven Spielberg almost got it right," says Murphy. But of course science can do better.