Thursday, December 11, 2008

Dinosaur "ghost" fossil revealed

MENLO PARK, Calif. — By the end of today, scientists hope that by using immensely powerful X-rays, they'll get pictures of a ghost. That is, the ghostly remains of a flying dinosaur bird that lived 150 million years ago.

When they're done, using new X-ray technology produced by electrons moving at or near the speed of light, they may have the clearest image ever recorded of what the creature's appearance and body composition. The 16-inch-long Archaeopteryx (pronounced aR-kee-OP-ter-iks) — or "ancient wing" in Greek — lived in the late Jurassic period.

An Archaeopteryx wasn't something you'd want coming towards you fast. Scientist started working late last week on a stone fossil originally discovered in Germany and now owned by the Wyoming Dinosaur Center. Within days, they had scans showing a creature with nasty sharp little teeth on its beak and two really pointy talons at the end of each wing.

"It's kind of like a bird stuffed up a dinosaur's butt," says University of Manchester paleontologist Phil Manning, one of the researchers.

When this particular creature died, it sank to the bottom of a shallow lagoon full of very salty water, where it was entombed in the limestone that preserved it as an amazing fossil. The Archaeopteryx is important because it's a crossover species, an example of evolution in motion, as one branch of dinosaurs was morphing into what would become the ancestors of birds. But only 10 Archaeopteryx fossils have been found, and of those only five are intact enough to tell us much.

The original idea of using new X-ray technology on fossils came from engineer and chemist Robert Morton of the Children of the Middle Waters Institute. His day job is doing chemistry for oil companies, which means he thinks about how to get information about things that might be hidden in very old rocks, such as oil. He heard a talk in the late 1980s and realized that the technique described could also be used to "see" the chemical ghosts of fossils.

Scientists at the Stanford Synchrotron Radiation Lightsource (SSRL) at the SLAC National Accelerator Laboratory, operated by Stanford University for the U.S. Department of Energy, are using this new method to tease out secrets that were embedded in the stone all those millions of years ago. The secrets may tell us more than we ever knew about how the Archeaopteryx lived and flew — and maybe even give us a few hints on how to store spent nuclear fuel as well.

The researcher are using synchrotron radiation, which produces intense X-ray beams, to build an elemental image of the creature. A single, intense beam is slowly scanned across the surface of the fossil.

As the X-ray bounces off the surface of the fossil, it creates a unique pattern that reveals the chemical composition of the remnants of the animal that are still preserved in the stone. Sometimes even those remnants are gone, but because other chemicals flowed in during fossilization to take their place in a fairly orderly manner, scientists can reverse-engineer what they see to imagine what once was there. The technique is called X-ray fluorescence imaging.

This enormous waterfall of data is then fed into a computer program that allows scientists to create an image of the leavings of a list of different elements — calcium, phosphorous, sulfur, zinc, copper and others. Seen alone or layered over one and other, they give an image of the "ghost" of a body that disintegrated millions of years ago, leaving only tiny traces of the elements it was made of behind.

Although the scan will be completed today, scientists will be working on the data for months. Then they'll submit it for publication in a scientific journal. By the conventions of the world of science, they can't release any images of anything new they've found before the paper comes out. So sometime late in 2009 or early 2010, keep an eye out for stories about the Ancient Feathered Dinosaur, and see what its wings really looked like.


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