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http://www.sciencedaily.com/releases/2009/02/
090215151858.htm
X-rays Used To Reveal Secrets Of Famous 'Dinobird' Fossil
ScienceDaily (Feb. 22, 2009) — About 150 million years ago, an evolutionarily
hybrid creature, a dinosaur on its way to becoming a bird, died in what is now
Germany, and become fossilized in limestone.
About 150 years ago, the fossil of this "dinobird" was discovered and
celebrated as proof of Charles Darwin's new theory of evolution.
Now fast word to a few weeks ago: The famous fossil, the Thermopolis specimen
of Archaeopteryx lithographica, made its way by truck from the Wyoming Dinosaur
Center to the Stanford Synchrotron Radiation Lightsource in California, where
it was meticulously scanned by one of the world's most powerful X-ray machines,
a building-sized device created for physics research.
By looking for traces of specific elements left in the slab of limestone as the
bird decomposed, the researchers hope to uncover heretofore-unseen details of
the soft tissue that once surrounded the well-preserved bones.
The X-rays, generated by SSRL's high-speed electrons as they race around a
260-foot-diameter ring, cause the elements to glow, revealing the ghost of soft
tissue or feathers.
"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, a member of the research team. "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."
"What you normally can't see are the chemical elements from the original
organism that might still be present in the fossil," said SSRL scientist Uwe
Bergmann. "Using X-ray fluorescence imaging, we can bring these elements to
light, getting a better look at the fossil and learning more about the original
animal."
"These X-rays work a thousand time better than what you could do with a
commercial X-ray machine. Only a synchrotron can do this," Bergmann said. SSRL
is part of SLAC National Accelerator Laboratory, which is operated by Stanford
University for the Department of Energy.
In addition to offering a new view of a long-extinct animal, this work may also
reveal more about fossilization itself. By understanding how fossilization
occurs and what exactly is preserved in the process, researchers will be able
to deduce much more about ancient organisms and evolution.
The Archaeopteryx fossil holds a unique place in history. It was brought to
London soon after Darwin published his stunning On the Origin of Species in
1859. With perfect timing, the old bones played a major roll in the controversy
Darwin had stirred up.
"This fossil was the savior of Darwin," Manning said. "As soon as it arrived in
London, all of Darwin's supporters realized that this was an intermediate
animal, an evolutionary freak that they needed to study. It was half way
between dinosaur and bird. This is the single most important fossil in
paleontology for that simple reason.
" It was used to beat the living daylights out of the nonsense which had been
put forward as to the reason for why animals were present on this planet. Here,
Darwin's theory of descendant with modification was hammered home with this one
example of transitionary form, of an animal between dinosaur and bird."
The fossil research is one example of how the SSRL is shining new light on
fields as diverse as paleontology, medicine, and the history of mathematics.
The SSRL's hair-thin X-ray beam has been used, for example, to make visible the
hidden writing in a medieval copy of a mathematical treatise from the Greek
mathematician Archimedes. Tuned to specific energies, the X-rays produced
images of phosphorus and calcium from the ink used on the papyrus document,
which had been covered with paint.
Earlier this year, at the request of Stanford library officials and an academic
researcher, the laser-like X-ray beam was used to scan a score by the Italian
composer Luigi Cherubini (1760 – 1842). Portions of the work had been covered
over with carbon-black ink, but after the scan, "The researcher was able to
look right through the ink and read the score," said Mary Miller, a Stanford
preservation librarian. "I think he was thrilled."
"This is the very infancy of this new scientific method," said paleontologist
Peter Larson of the Black Hills Institute in South Dakota. "We don't even know
enough about this to know the right questions to ask yet. All of a sudden, we
can look at fossils in a very different and new way."
Adapted from materials provided by Stanford University. Original article
written by Dan Stober.
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Stanford University (2009, February 22). X-rays Used To Reveal Secrets Of
Famous 'Dinobird' Fossil. ScienceDaily. Retrieved February 23, 2009, from
http://www.sciencedaily.com /releases/2009/02/090215151858.htm
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