Ever since the first skeleton was found in 1861, the remains of the feathered dinosaur (and earliest known bird) Archaeopteryx have been highly prized for their potential to shed light on the origin of birds. There are about eight specimens presently known, many of which possess feather impressions, and scientists treat these rare specimens with great care. As paleontologist Dave Hone has documented on his blog, however, in some cases preparation of these fossils has destroyed important features that can no longer be seen. In order to preserve the important details of a fossil, sometimes scientists have to hold back from picking away at it to see what might be underneath the rest of the slab.
Fortunately, 21st century technology has allowed paleontologists to get a better look at delicate fossils without risking damage to them. This month one of the best-preserved Archaeopteryx fossils, known as the Thermopolis specimen, at left, was sent from its home in Wyoming to the Department of Energy's SLAC National Accelerator Laboratory at Stanford for analysis. There the entire slab was scanned with an intense X-ray beam that can show the presence of ancient chemicals and parts of the animal otherwise invisible. (Scientists there recently used a similar technique to read a hidden text by Archimedes.) The chemicals may be the remnants of the dinosaur or of bacteria that covered it and took its shape as it decomposed, but either way they might represent a second “chemical impression” that has not been seen before.
This is the first time that this kind of technique has been applied to fossils, and paleontologists are unsure as to what they will find. If the test is a success and reveals parts of the fossil hitherto unknown, then expect a lot more delicate specimens to undergo similar analysis. For now, though, we’ll just have to wait for the paper to be published in a few years.