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Tuesday, 04 December 2007 |
Dinosaur Mummy Found With Skin Intact
Scientists have announced the discovery of what appears to be the world's most intact dinosaur mummy: a 67-million-year-old plant-eater that contains fossilized bones and skin tissue, and possibly muscle and organs. Preserved by a natural fluke of time and chemistry, the four-ton mummified hadrosaur, a duck-billed herbivore common to North America, could reshape the understanding of dinosaurs and their habitat, its finders say.
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"There is no doubt about it that this dinosaur is a very, very significant find," said Tyler Lyson, a graduate student in geology at Yale University who discovered the dinosaur in North Dakota. The 25-foot-long hadrosaur was found in an ancient river flood plain in the dinosaur-rich Hell Creek Formation.
"To say we are excited would be an understatement," said Phil Manning, a paleontologist at England's University of Manchester who is leading the examination. "When I first saw it in the field, (I thought) 'Shiiiit, that's a really well preserved dinosaur.' It has the potential to be a top-10 dinosaur, globally." He stated “This specimen exceeds the jackpot. We’re looking at three-dimensional skin envelope. In many places it’s complete and intact - around the tail, arms, and legs and part of the body.”
Nicknamed Dakota, the hadrosaur is one of only five naturally preserved dinosaur mummies ever discovered. Unlike previous dinosaur mummies, which typically involve skin impressions pressed into bones, Dakota's entire skin envelope appears to remain largely intact.
 "The skin has been mineralized," said Manning. "It is an actual three-dimensional structure, backfilled with sediment." The fidelity of the envelope, he said, raises the possibility that Dakota could contain other soft-tissue remnants, including muscles and organs.
"This is not a skin impression. This is fossilised skin," said Dr. Manning, "When you run your hands over the skin, this is the closest you are going to get to touching a real dinosaur, ever."
"He looks like a blow-up dinosaur in some parts," said Dr. Manning,"When you actually look at the detail of the skin, the scales themselves are three dimensional. . . . The arm is breathtaking. It's a three-dimensional arm, you can shake the dinosaur by the hand. It just defies logic that such a remarkable specimen could preserve."
Although it is described as "mummified," the 65 million-year-old duckbilled dinosaur that scientists have named Dakota bears no similarity to the leather-skinned human mummies retrieved from ancient tombs in Egypt. Time long ago transformed Dakota's soft tissue into mineralized rock, preserving it for the ages. "It's a dinosaur that was turned into stone, essentially," said Lyson, 24, now a graduate student in paleontology at Yale University.
 How Dakota perished is a mystery, but his death came near a river, and his body, curled in the fetal position, was quickly covered in water, wet sand and other sediment. The carcass was visited by at least one scavenger, a crocodile of the era that, Manning said, may have become stuck while feeding and died. Scientists found its preserved arm poking through Dakota's chest.
"It's a fossil within a fossil," Manning said. "We were over the moon when we found it."
Over time, weak acids in the sediment probably helped form the siderite, or iron carbonate, that encased both bodies and preserved them for millions of years, the researchers said.
A lifelong dinosaur enthusiast, Lyson has been strapping on a backpack and hunting (and finding) dinosaur bones in the arid outback of his home state ever since elementary school. He even started an organization, the Marmarth Research Foundation in his home town of Marmarth, N.D., to support education and research on dinosaur fossils.
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. A pretty good find, Lyson thought, but not outstanding. He marked the location in his notes and moved on.
But in 2004, after leading a team of amateur researchers in an excavation that did not pan out, a disappointed Lyson turned his attention again to the vertebrae he had left behind five years before.
"I didn't have very high hopes for the animal," Lyson said. "I figured the excavation would take two or three weeks, I'd have a hadrosaur tail, it would make a nice museum piece, but scientifically it would not be that impressive."
After finding a small piece of fossilized skin, however, Lyson knew he was onto something special. A friend at the dig knew Manning, and within months, Lyson and he had agreed to pursue the project.
They completed the excavation in summer 2006, removing a 10-ton block containing most of Dakota's body and a four-ton block with most of the tail. These were later whittled down to about four tons and less than a ton, respectively. Researchers are studying them with common tools such as tweezers but also with massive CT scanners at a facility near los Angeles formerly used by NASA and Beoing.
Only after the body and a chunk of the hillside was moved to a lab did the scientists realize the extent of the discovery. "On vast areas of the tail and body," Manning said, "there was what looked to be a three-dimensional skin envelope, in the same way as a sock around your foot -- which did not make any sense at all."
 "It is quite fair to say that our dinosaur mummy makes many other dinosaurs look like road kill. Simply because the evidence we're getting from our creature is so complete compared to the disjointed sort of skeletons that we usually have to draw conclusions from," said Dr. Manning.
Manning brought on dozens of scientists and engineers -- in disciplines ranging from computer science to organic chemistry and physics -- to investigate every aspect of the find using state-of-the-art tools.
"Up until Phil showed me this dinosaur," said Roy Wogelius, a geochemist from the University of Manchester studying the soil surrounding Dakota, "I had no interest in dinosaurs. As soon as I saw this specimen, I was fascinated."
Already, the scientists say they have made fascinating discoveries. The skin around the tail and on large swaths of the body appears generally in its original shape rather than squashed flat against the bones, giving researchers a three-dimensional look at Dakota. They can see both legs and arms and the chest cavity. The head and neck are not visible, but the researchers think they may be folded within the body block. They do not know whether the internal organs are there, nor have they determined the creature's sex, although they refer to it as a male.
The scientists have felt the scales near Dakota's elbow, noticing that they vary in size -- an indication, perhaps, of changes in skin color, texture or flexibility. They found a fleshy pad on its palm, an indication that it did not permanently walk on all fours, and keratin hooves on its feet.
The areas of uncollapsed skin have aided researchers in reconstructing Dakota's muscle sizes and allowed them to see, for instance, that a hadrosaur's backside was about 25 percent larger than previously thought. They estimate that Dakota could run as fast as 28 mph, faster than a Tyrannosaurus rex, the top predator of the time.
In North Dakota, the researchers used Light Detection and Ranging equipment (LiDAR) to develop a three-dimensional topographical map of the area where Dakota died. Manning speculated that the dinosaur collapsed in a riverbed during the late Cretaceous Period and was rapidly buried in mineral-rich wet sand, preventing bacteria from devouring all of its tissue. "There was active-enough chemistry in the sediments that the decay process didn't occur as quickly as the mineralization process," he said. "It was a perfect chemical soup."
After examining the dinosaur at a local lab, the scientists encased it and the remaining surrounding soil in plaster and hauled it by truck to a Boeing research center in Canoga Park, California, north of Los Angeles. There, Boeing volunteered the world's largest computerized tomography, or CT, scanner, originally built by NASA to scan space shuttle parts for flaws. At 8,000 pounds, the fossil became the largest object ever scanned at high resolution. The researchers are using the data to survey the body's interior before chipping away further on the fossil. "The CT scan is like a roadmap," said Manning. "It will help us recover the rest of the animal more easily and efficiently."
The first significant findings from the dinosaur, currently under review at a major scientific journal, will describe the unique chemical balance that preserved the fossil. The body, meanwhile, remains on the Boeing scanner, as Manning and his colleagues sift through terabytes of data. So far, they have determined that the hadrosaur's hindquarters are 25 percent larger than previously thought for the species, meaning that it could run up to 28 mph -- faster than previously estimated. They have also discovered that the specimen's vertebrae, which museums commonly stack together, are actually spaced 10 millimeters apart. The result, Manning said, implies that scientists may have been underestimating the size of hadrosaurs and other dinosaurs.
The National Geographic Channel, which helped fund the research, will recount the saga of Dakota's discovery in a documentary, Dino Autopsy. Manning is also publishing a book, Grave Secrets of Dinosaurs, describing the fossil and its history. Although there are a lot of scientists involved in the project, Lyson and Manning have not yet allowed experts outside the project to assess the mummified dinosaur.
But the scientific findings from the specimen may take decades to exhaust. "I'm 40 years old now," Manning said. "If I live till 80 I think I'll still be at the tip of the iceberg."
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