Hundreds of Dino-Era Animals in Amber Revealed by X-Ray

Ker Than
for National Geographic News
April 4, 2008
A hidden trove of fossilized treasures in cloudy ancient tree sap have been brought to light with a new form of "x ray vision," scientists announced recently.

Fossilized tree sap, or amber, is usually transparent but can become murky due to contamination by dirt and other debris.

The dirtiest type, called opaque amber, resembles rocks and is a challenge for paleontologists who want to see organisms trapped inside.

That is changing with synchrotron imaging, which uses high-energy x-rays generated by accelerated electrons to examine hidden fossils.

"Researchers have tried to study this kind of amber for many years with little or no success," study co-author Paul Tafforeau, a paleontologist at the European Synchrotron Radiation Facility in France, said in a statement.

In a new study, scientists used the technique to reveal hundreds of organisms—mostly insect—entombed in opaque amber since the time of the dinosaurs.

(Related news: "Dino-Era Feathers Found Encased in Amber" [March 11, 2008].)

The work will appear in an upcoming issue of the journal Microscopy and Microanalysis.

Virtual Extraction

The researchers imaged 640 pieces of Cretaceous-period amber from the Charentes region of southwestern France.

First the team had to pinpoint the locations of the encased fossils.

When synchrotron x-ray beams penetrate an object, different materials can modify their wavelength shapes in various ways.

By examining altered x-rays, scientists can create "phase contrasts" in which the fossils stand out clearly against the amber.

Once the fossils' positions are known, they are again exposed to a synchrotron beam—but this time while being rotated.

The team then "virtually extracted" 356 exquisitely detailed fossil organisms, which included microscopic mites, larger wasps, flies, spiders, and plant remains.

The digital images can also be scaled up or printed to create physical models.

Improved Technique

David Grimaldi is an amber expert at the American Museum of Natural History in New York City, who helped pioneer the use of imaging technology to study insect fossils.

(See a photo of a digitally dissected ancient spider.)

Grimaldi, who was not involved in the new work, said it was an improvement over past techniques, which relied on CT scanners similar to those used in hospitals.

With synchrotron imaging, fossils that were previously inaccessible can now be studied, Grimaldi said.

"Most of the amber that comes from the Cretaceous deposits in France is opaque," he said.

"A dense suspension of organic particles [makes] it difficult to see more than a few millimeters into the piece."

Recreated Skin?

Other researchers, such as Uwe Bergmann, a senior scientist at the Stanford Linear Accelerator Center in California, are employing related synchrotron-based x-ray techniques to create "elemental maps" that highlight specific chemical elements in fossils.

"If you create an image of calcium, you bring out [the bones] much clearer," Bergmann said.

By focusing on other elements, scientists could one day reconstruct the skin and soft tissues of ancient animals.

"In the fossilization process, the skin and everything turns into stone, but some of the chemical elements of the original skin are still trapped in there," he said.

(Related news: 'Dinosaur Mummy' Found; Has Intact Skin, Tissue" [December 3, 2007].)

"What we would love to do is recreate the soft tissue or stomach contents of something that has not lived for millions of years."

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