An onsite restoration drawing of how "Leonardo" may have looked before burial based on observations and measurements of the specimen. The drawing was done by paleolife artist Greg Wenzel.
Art copyright Judith River Dinosaur Institute
His fossilized skeleton is covered in soft tissue—skin, scales, muscle, foot pads—and even his last meal is in his stomach. The actual tissue has decayed over the millennia, and has been replaced by minerals. What’s left for scientists to study is a fossil of a dinosaur mummy.
"For paleontologists, if you can find one complete specimen in a lifetime, you’ve hit the jackpot," said Nate Murphy, curator of paleontology at the Phillips County Museum, Montana, where Leonardo makes his home. "To find one with so much external detail available, it’s like going from a horse and buggy to a steam combustion engine. It will advance our science a quantum leap."
Leonardo is one of the most complete brachylophosaurus dinosaur fossils uncovered to date, and the first sub-adult. He is also only the fourth dinosaur fossil in the world to be classified as a "mummy" because of the soft tissue that is preserved.
The other three mummies were uncovered in the early 20th century, when excavation and preservation techniques were not as advanced as they are today.
"Paleontologists back then didn’t have the techniques we have today to coax out the secrets these fossils are holding," said Murphy. "This specimen gives us a chance to apply modern scientific techniques to answer old questions."
The mummified fossil was named Leonardo because graffiti near its burial site in northern Montana read "Leonard Webb and Geneva Jordan, 1917." Leonardo made his debut to the scientific community today at the 62nd Annual Meeting of the Society of Vertebrate Paleontology, taking place October 9-12, in Norman, Oklahoma.
Remarkable State of Preservation
When he died, Leonardo was a 22-foot-long (seven meters) teenager, weighing between 1.5 to 2 tons. He sported polygonal, five-sided scales that ranged from the size of a BB (airgun pellet) to the size of a dime, and soft-tissue structures on his back suggest that he had a little sail frill running up it.
Scales and tissue parts have been found on less than one-tenth of one percent of all dinosaurs excavated. Leonardo’s fossilized skeleton is about 90 percent covered in soft tissue, including skin, muscle, nail material, and a beak. Skin impressions have been found on the underside of the skull and all along the neck, ribcage, legs, and left arm.
"When the animal was alive, the skin was almost as soft as your earlobe," said Murphy.
A three-dimensional rock-cast of the right shoulder muscle and throat tissue, and the pads on the bottom of the three-toed foot were also preserved.
Leonardo’s stomach contents are so well-preserved that researchers can tell what he had for his last supper; a salad of ferns, conifers, and magnolias. The stomach also contained the pollen of more than 40 different plants.
All of these qualities should go a long way to providing concrete information about the diet, range of movement, methods of locomotion, and paleo-environment dinosaurs during the late Cretaceous (89 to 65 million years ago) experienced.
"We have the shoulder muscle to look at, so we can see how much range of motion he had," said Murphy. "We should be able to tell the size of his average step, how his chest muscles worked, and if he was truly a quadruped or if he was bipedal."
"Paleontology is not an exact science," he said. "All we have are bones, and from there we develop theories about what the animals looked like, how they moved, and what they ate. A specimen like Leonardo will take a lot of guess work out and really tell us if Steven Spielberg’s getting it right."
Discovery and Excavation
Dan Stephenson, of Minot, North Dakota, discovered Leonardo during the last hour of the last day of a summer expedition in 2000 sponsored by the Judith River Dinosaur Institute.
"He had the wisdom to not mess with it," chuckles Murphy. "He went and got me and I knew right away we had a complete skeleton. Looking at the geology, I told the team that this was a great scenario for skin fossilization."
Excavation began in the summer of 2001, when a demolition expert, using low-impact charges, cleared away the huge boulders on the top of the hillside. A road to the site was cut, and a bulldozer was called in to scrape off the hilltop. Team members dug a six-foot -deep (two meters) trench around the fossil’s perimeter, and then went in with hand tools—the scalpels, brushes, and dental picks that are a paleontologist’s tools of trade.
Leonardo was disinterred from his cement-like grave as a single 6.5-ton block to preserve the skeleton. "He’s in the record books as the largest dinosaur taken out in one chunk; it was a monumental undertaking," said Murphy.
The scientific work on Leonardo will keep paleontologists occupied for years.
"It’s like looking through a frosted glass window. With bones you get an idea of what the animal looked like, but with soft tissue you get to see how the animal is put together—it goes a long way to clearing the frost," said Murphy.
Source: National Geographic News, October 11, 2002