April 10, 2008
Fossilized Snake With Two Legs Found
Researchers at the National Museum of Natural History, Paris were thrilled to finally confirm that a slab of Lebanese limestone depicts the body of a snake with two legs.
Researchers at the European Light Source (ESRF) in Grenoble, France used a high-powered super camera to validate their suspicions about the fossilized reptile.
Alexandra Houssaye, from the National Museum of Natural History, Paris, said that the X-ray technique is useful because it allows researchers to get an in-depth glimpse of the inner structure of the creature without damaging the specimen.
"We were sure he had two legs but it was great to see it, and we hope to find other characteristics that we couldn't see on the other limb," said Houssaye.
Known as Eupodophis descouensi, the reptile is 33 inches long and comes from the Late Cretaceous, about 92 million years ago.
"It's very rare," Houssaye said of the specimen. "There are only five or six species known, and there are only three species with a leg preserved. So, it's very unique."
Although part of the vertebral column is absent and the tail has become detached and positioned near the head, the fibula, tibia and femur are unmistakable. Its hind limb is only 0.8 inches long, and researchers said it was most likely useless to the creature.
In the genealogy of snakes, two theories are prevalent. One theory states that as lizards started to adapt to their subterranean existence, their forelimbs and hind-limbs were eventually eliminated.
Another theory says that the snake originated from a habitat primarily composed of water.
"Every detail can be very important in establishing the great relationships and that's why we must know them very well," said Houssaye.
"I wanted to study the inner structure of different bones and so for that you would usually use destructive methods; but given that this is the only specimen [of E. descouensi], it is totally impossible to do that. 3D reconstruction techniques were the only solution. We needed a good resolution and only this machine can do that," she said.
The recent discovery was made largely in part by the European Synchrotron Radiation Facility, which has proven its extensive imaging capabilities in the past by enabling archaeologists to study fossils of ancient minute insects in samples of opaque amber.
Researchers fixed the reptilian fossil to a table that was rotated in front of the powerful X-ray beam to produce an interwoven and very detailed 3D image.
The finished product, which can be spun around on a computer screen, reveals details that will be measured in just millionths of a meter.
"We can even see ankle bones," ESRF's resident palaeontologist Paul Tafforeau said.
"In most cases, we can't find digits; but that may be because they are not preserved or because, as this is a vestigial leg, they were never present."
On the Net:
European Synchrotron Radiation Facility
National Museum of Natural History
BBC News Video