By Lisa M. Krieger
Mercury News
Stanford scientists are using powerful X-ray beams on a rare feathered dinosaur that perished more than 150 million years ago in an effort to see its inner tissues and perhaps someday understand the anatomical split that sent birds and reptiles down different evolutionary paths.
The archaeopteryx fossil has come to SLAC Laboratory to undergo a revolutionary analysis. (Courtesy of SLAC)
At SLAC’s Stanford Synchrotron Radiation Lightsource in Menlo Park, the scientists are using the beams to scan one of the world’s most valuable fossils, delicately transported by pickup truck from its home in a Wyoming dinosaur museum.
The X-rays, generated by a particle accelerator, cause tiny amounts of a dozen chemicals to glow without harming the ancient fossil, believed to be the earliest representation of a bird.
Scientists hope the chemicals will correlate with organs, blood vessels and other interior parts of the creature, called archaeopteryx, or “ancient wing,” which has both reptilian and avian features. When compared with scans of other fossils, such anatomical information could help explain evolutionary changes.
“What we are hoping is that we will learn more information than just what you can see with your eyes,” said Uwe Bergmann, staff scientist at SSRL. “The body decays, but the chemical elements — silicon, calcium, potassium, iron, all the chemicals which make up living animals — some of them will be preserved.”
What is visible in stone is just a faint imprint of a physical feature, such as a feather, he said. But soft tissues have unique chemical characteristics that aid in their identification. For instance, calcium would suggest a bone; iron might mean blood. By measuring the distribution of these chemicals in a fossil, it may be possible to re-create anatomy — and hence, evolution.
The latest effort is not the first time the intensely bright X-rays, emitted by particles circulating near the speed of light, have been used to solve ancient mysteries. In 2005, they helped decipher a 10th century manuscript that contained rare copies of works by the mathematician Archimedes.
But the tool brings new possibilities to our understanding of archaeopteryx. Some of the 10 known specimens of the creature have previously undergone extensive visual analyses and even CT scans, but nothing as comprehensive as the X-ray imaging researchers are utilizing at SSRL.
Archaeopteryx holds a unique place in history. When the first specimen was discovered about a century and a half ago, just a year after Charles Darwin published “On the Origin of Species,” its shared reptile-avian features provided the strongest evidence yet for the theory of evolution.
The Jurassic-era fossil has a beaklike mouth, winglike forelimbs, long feathers and feet for perching. But it also has reptilelike teeth in its jaws, claws on its fingers and a long tail. A little over a foot long, it could probably fly — but without the grace of modern birds.
“If you want to find a single fossil which is a missing link in the evolution of dinosaurs into birds, this is it,” said University of Manchester paleontologist Phil Manning. “It’s a bird with sharp teeth, claws and a long bony tail. If you were to freeze-frame evolution, you would end up with archaeopteryx.”
Millions of years ago, the creature under study at SSRL sank to the bottom of a shallow lagoon and became entombed in limestone near Solnhofen, Germany. It is now owned by the Wyoming Dinosaur Center, located in Thermopolis, Wyo.
Last weekend, scientists packed the creature into a small wooden box, loaded it into the cab of a white Chevy Silverado truck and drove the 850 miles to SLAC. Upon its arrival Monday night, it was moved into a helium-filled tray for analysis.
The creature heads back home after the weekend. Then, for SLAC scientists, the real work begins.
“We could build up a library of samples,” Bergmann said. “We’d start out with parts of creatures that are still in existence — let’s say, a bird’s feather, or maybe the shells of turtles or skins of lizards. Then we could do more fossils. Once you have all that information together, it’s possible to compare.”
“I don’t see that one measure of archaeopteryx will provide all the answers,” he said. “But if we work hard and very broadly, studying lots of samples, I think we’ll be in for a surprise.”
Contact Lisa Krieger at lkrieger@mercurynews.com or (408) 920-5565.
source: http://www.mercurynews.com/ci_11188177?nclick_check=1
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Technology gets fossil to reveal its secrets
David Perlman, Chronicle Science Editor
Saturday, December 13, 2008
(12-12) 19:19 PST – Physicists aimed Stanford’s mighty beam of high-energy X-rays on a stone fossil of a 150 million-year-old bird Friday in the first effort to discover what chemical mysteries of evolution lie inside the ancient creature.
The famed bird is an Archaeopteryx, the oldest known example of the flying dinosaurs that evolved long, long ago from more familiar creatures like Tyrannosaurus rex and the vicious Velociraptor.
It is, in fact, a major missing link between early dinosaurs and their descendants, the modern birds.
“This is one of the most important fossils on the planet,” said Phillip Manning, a paleontologist from England’s University of Manchester. “Any information about its elements and its chemical compounds that we can tease apart from its body with the X-ray beam from Stanford’s huge machine will let us compare it to the chemicals that changed during its evolution into modern birds.”
Those chemical changes over millions of years between flying dinosaurs and birds could reveal processes of evolution that Charles Darwin himself never dreamed of.
Inside the Stanford Synchrotron Radiation Lightsource at the SLAC National Accelerator Laboratory, the 16-inch square slab of stone holds a virtually complete but vague impression of the bird as it must have died in some ancient muddy lake bed. It reveals only outline sketches of its wings, legs, skull and twisted body.
‘Thermopolis Fossil’
Known as the “Thermopolis Fossil,” the bird has a mysterious past and a bit of the Maltese Falcon in it, too.
No one knows when it was actually discovered in Germany’s well known Solnhofen dinosaur quarry, but it later appeared somehow in the estate of an unnamed Swiss fossil collector who died 40 years ago.
It is one of only 10 Archaeopteryx fossils ever found – the first one was discovered only two years after Darwin published his “On the Origin of Species” in 1859. Like the others, this one is immensely valuable. At some point, an anonymous donor put up funds to buy it from the Swiss collector’s widow and ship it to the Wyoming Dinosaur Center, a museum in Thermopolis, Wyo., where it is on “permanent loan.”
The idea for X-raying the fossil first came from Robert Morton, an oil company chemist in Bartlesville, Okla., and its transport to Stanford was arranged by Peter Larson of the Black Hills Institute of Geological Research in South Dakota, which offers a wide variety of fossils for sale.
On Friday, SLAC’s synchrotron lightsource aimed its intensely bright X-ray beam at the fossil’s surface to reveal the structure of the Archaeopteryx’s interior bones and tiny teeth, and even hint at its soft tissues. Each individual chemical inside the fossil emitted a specific frequency of fluorescent light that identified it, Manning said.
Uwe Bergmann, a physicist at SLAC, runs the synchrotron lightsource, where X-ray beams are generated by magnets tapping a stream of electrons racing at 3 million electron volts inside a storage ring and accelerated to nearly the speed of light.
The stuff of ancient birds
In a short time, the beam has already identified an entire roster of the bird’s elements: sulfur, phosphorous, copper, zinc, manganese, calcium and more, Bergmann said, and the experiment will continue this weekend in a hunt for organic compounds, too.
“But we were puzzled when the X-rays revealed something we hadn’t expected,” he said. “Then we realized it was only varnish – a thin coat of varnish that someone had applied to part of the fossil some time after it was found in Germany.”
Although he’s a physicist, Bergmann’s interests are wide: More than three years ago, he and his SLAC team aimed their super-X-ray beam at a layer of goatskin parchment many centuries old bearing a copy of writing by Archimedes, the Greek scientist, on mathematics. The document has become famed as the “Archimedes Palimpsest” – a palimpsest being a segment of writing on which someone has written something else on top of it. Some of Archimedes’ words had been covered by later writings.
The synchrotron’s X-ray beam revealed the very words in the Archimedes parchment that had been hidden from human eyes for many centuries.
Now Stanford’s X-ray beam – an essential tool for physicists and material scientists – is lending a hand to biologists, too, helping to reveal the inner secrets of a 72 million-year-old duck-billed dinosaur and an ancient jellyfish.
This article appeared on page A – 1 of the San Francisco Chronicle
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/12/13/MNCV14N2R3.DTL
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Dinosaur “ghost” fossil revealed
USA Today - 21 ore fa
Scientist started working late last week on a stone fossil originally discovered in Germany and now owned by the Wyoming Dinosaur Center.
Scientists scan birdlike dinosaur for evolution clues St. Louis Post-Dispatch
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