A new breakthrough means that we can finally detect the red color in ancient fossils

About 3 million years ago, a tiny mouse with a reddish fur on the back and a white belly roamed the landscape of what is today Germany. We know this thanks to a remarkable new breakthrough in which a reddish pigment was detected in an ancient fossil, a first scientist.

Fossils with traces of soft tissue are exceptionally rare, which prevents scientists from determining the color of a sample, the texture of its skin and other important aesthetic and functional features. Without this information, scientists can not know for sure when certain physical characteristics have appeared in a species and how they have evolved over time.

A new study published Tuesday in Nature Communications describes a new technique allowing scientists to detect for the first time a reddish-colored pigment in a mouse fossil aged 3 million years. Using X-ray spectrography, chemical imaging and other techniques, researchers at the University of Manchester and several other institutions have shown that the extinct mouse has a reddish-brown fur on the back and a white belly . It is interesting to note that this new technique could be used to detect the reddish color on other fossils with traces of soft tissue.

"The fossils we have studied have the immense potential to reveal many secrets of the organism of origin. We can reconstruct the essential aspects of life, death and subsequent events affecting preservation before and after burial, "said Phil Manning, chief paleontologist and professor at UM, in a press release. "To undo this complex archive of fossil chemicals, an interdisciplinary team is needed that works together to solve this problem."

Indeed, the new study used experts in physics, paleontology and chemistry according to Manning. A key challenge was to develop a new technique for distinguishing red pigments from an old fossil. To do this, researchers had to map the chemical elements associated with melanin pigment, the dominant pigment in animals. For the red color, the version of melanin is pheomelanin and for the black color, it is eumelanin. In fossils, the red pigment is rarer and more difficult to detect because it is less stable over long periods.

Before this new study, scientists had already developed a technique for detecting eumelanin in ancient fossils. This was done, for example, to show that archeopteryx, a dinosaur resembling an early bird, had black feathers. In the same vein, the paleontologists at Bristol University used a similar approach to show that some dinosaur undersides had a lighter color and a darker color, a form of camouflage known as name of "counter-shading".

Three years ago, Nick Edwards, co-author of the new study and researcher at the SLAC National Accelerator Laboratory, showed that it was possible to distinguish eumelanin pigments from pheomelanin pigments in modern birds. . This discovery helped to establish an important preparatory work for the new study. .

"We had to create a solid foundation using modern animal tissues before we could apply the technique to these ancient animals," Edwards said in a statement from SLAC. "It was really a critical point in the use of chemical signatures to break the staining of old animals with soft tissue fossils."

For the new analysis, the researchers used an extraordinary fossil of a dead mouse, 3 million years old, discovered near the German village of Willershausen. The fossil, dubbed the "powerful mouse," has been scanned by X-ray sources at Stanford's synchrotron light sources and the Diamond Light Source light source in the UK. This allowed researchers to study X-ray interactions with fossil chemistry. The trick was to spot traces of metals that were once present in the soft tissues of living organisms.

"Where we had just seen minerals, we are now gently stripping away the" biochemical ghosts "of extinct species for a long time," Manning said.

Observations have shown that trace metals in the fossil bind in the same way as organic chemicals in living creatures with high concentrations of red pigment in their tissues. This resulted in the identification of pheomelanin in the fossilized mouse fur.

"Finding a counter-shading in a 3 million-year-old mouse is a neat task and shows how modern analytical techniques can reveal important information that traditional study methods would likely have missed," he said. Michael Pittman, paleontologist at the University of Hong Kong. new study, said to Gizmodo.

Pittman said his own work on the development of laser-stimulated fluorescence imaging was similar in this respect, which he had used to reveal the first example of counter-shading in dinosaurs.

It is interesting to note that this new non-destructive technique could be used to study other fossils.

"The resolution of the pigment residues of pheomelanin should now be possible, by combining chemical imaging and X-ray spectroscopy, at least for specimens of an age equal to or less than 3 million years," write the authors in this new study.

Hopefully these future efforts will continue to add color to what was once a monochrome.