What color was T. Rex? What about triceratops or glyptodone? Until recently, the priest's gallery was the only proceeds of daydreams, CGI artists or children with crayons.
Advances in imaging technology bring us closer to real answers. Over the last decade, we have learned that Sinosauroptery tail was striped, and Microraptor's head was blue black and shiny like a collar.
A paper published Tuesday in Nature Communications adds to the paint box. In it, a research group gives the first crucial fossil proof that an old creature contained pheomelanin ̵
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Even in well-preserved fossils, the pigments deteriorate rapidly. Scientists have a few solutions to find traces of color. Some look for melanosomes, the organelles in animal cells that produce and store pigments. The shape of a melanosome may indicate what type of pigment was once inside, while the organization of melanosomes within a feather may indicate whether a bird (or dinosaur) was dull or iridescent.
Another technique is to look for more sustained molecules known to be associated with pigments. It is the preferred tactic for this research group that earlier found signs of eumelanin – a brown and black pigment – in the feathers of the fourth dinosaur Archeopteryx.
For this new study, the researchers worked with two copies of an extinct field mouse, Apodemus atavus. Three million years ago, several of these mice died and were washed in a pond in what is now Willershausen, Germany. Quickly buried by the sediment, they were spared many of the havoc of bacteria and time and ended up in a fossil drawer at the Geosciences Museum at Göttingen University.
"I saw the extraordinary preservation of fur," says Dr. Manning, geologist at the University of Manchester and the main author of the paper. "I realized," Bloody hell, these are worth scanning! ""
The mice were sent to the SLAC National Accelerator Laboratory in California, where they were driven through a special X-ray that revealed their chemical structure. The X-rays work fine enough to detect "a little sulfur, or a bit of zinc or copper," says Uwe Bergmann from Stanford who ran the machine. "We can get maps of different items very quickly." (Dr. Bergmann originally came up with this technique in the early 2000's to reveal ink on deleted and occluded pages of Archimedes Palimpsest.)
Next, the team used spectroscopy to zoom in on two key elements: zinc and sulfur. In today's mammals and birds, pheomelanin is closely linked to particular zinc sulfur compounds. The researchers also saw these in fossils, which means that their fur had been filled with the reddish pigment. They found a higher concentration of them on the dorsal side, suggesting that the mouse had a lighter stomach.
"By understanding the delicate relationship between zinc and sulfur, we can say for the first time with certainty:" Yes, this is pheomelanin pigment in the fossil record, "Dr. Manning says.
More important than their conclusion If the color of the mouse is what their process allows, earlier methods of detecting color were piecemeal or destructive, but "this new method seems to allow the mapping of color pigments across an entire fossil," said Mike Benton. Paleontologist at the University of Bristol who was not involved in the study.
The group is working on further streamlining of the scanning method "so that it is easy for everyone to come and bring fossils," says Dr. Bergmann.
Prehistoric World, get ready to start blushing.