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Research paints new picture of “dinobird” feathers

June 13, 2013
Courtesy of DOE/SLAC National Accelerator Laboratory
and World Science staff

The feath­ers of Ar­chae­op­ter­yx, a fa­mous fos­sil link­ing di­no­saurs and birds, were not all black, but rath­er pat­terned—light-col­ored with a dark edge and tip, a new chem­i­cal anal­y­sis in­di­cates.

The find­ings, over­turn­ing pre­vi­ous think­ing about the feath­er hues, came from X-ray ex­pe­ri­ments at the U.S. De­part­ment of En­er­gy’s SLAC Na­t­ional Ac­cel­er­a­tor Lab­o­r­a­to­ry. There, sci­en­tists found chem­i­cal traces of the orig­i­nal di­no­bird and its pig­ments in the rock that en­tombed it an es­ti­mat­ed 150 mil­lion years ago.

An artist's il­lus­tra­tion of how Ar­chae­op­ter­yx may have looked sport­ing its new pig­men­ta­tion. (Cour­te­sy U. of Man­ches­ter)


“This is a big leap for­ward in our un­der­stand­ing of the ev­o­lu­tion of plum­age,” said Phil­lip Man­ning, a pa­le­on­tol­ogist at the Uni­vers­ity of Man­ches­ter, U.K. and lead au­thor of the re­port in the June 13 is­sue of the Jour­nal of An­a­lyt­i­cal Atom­ic Spec­trom­e­try.

Only 11 Ar­chae­op­ter­yx spec­i­mens have been found, the first con­sist­ing of just one feath­er. Un­til a few years ago, re­search­ers thought all the bones and tis­sues of the orig­i­nal an­i­mal would have been re­placed by min­er­als dur­ing fos­sil­iz­a­tion, leav­ing no chem­i­cal traces be­hind.

But two re­cently de­vel­oped meth­ods have turned up more in­forma­t­ion about the di­no­bird and its plum­age.

The first is the dis­cov­ery of melanosomes—mi­cro­scop­ic struc­tures con­tain­ing pig­ment—in fos­sils. A team led by re­search­ers at Brown Uni­vers­ity in Rho­de Is­land an­nounced last year that an anal­y­sis of melanosomes in the Ar­chae­op­ter­yx feath­er spec­i­men showed that the feath­er was black. They iden­ti­fied the feath­er as a cov­ert—a type of feath­er that co­vers the pri­ma­ry and sec­ond­ary wing feath­ers—and said its heavy pig­menta­t­ion may have strength­ened it against the wear and tear of flight, as it does in mod­ern birds.

How­ev­er, that study ex­am­ined melanosomes from just a few loca­t­ions in the fos­silized feath­er, said SLAC’s Uwe Bergmann. “It’s ac­tu­ally quite a beau­ti­ful pa­per,” he said, “but they took just ti­ny sam­ples of the feath­er, not the whole thing.”

The sec­ond is a meth­od Bergmann, Man­ning and Roy Wogelius of the Uni­vers­ity of Man­ches­ter de­vel­oped for rap­idly scan­ning en­tire fos­sils and an­a­lyz­ing their chem­is­try with an X-ray beam at SLAC’s Stan­ford Syn­chro­tron Radia­t­ion Light­source.

Over the past three years, they led a team that used this meth­od to dis­cov­er chem­i­cals left by the di­no­bird’s bones and feath­ers in the sur­round­ing rock, as well as pig­ments from the fos­silized feath­ers of two of the first known birds. This let them rec­re­ate the plum­age pat­tern of a bird that lived more than 120 mil­lion years ago.

In the lat­est stu­dy, the team scanned the en­tire fos­sil of the first Ar­chae­op­ter­yx feath­er with the X-ray beam. They found trace met­als as­so­ci­at­ed with pig­ments and or­gan­ic sul­fur com­pounds that could only have come from the an­i­mal it­self. The fact that these com­pounds have been pre­served in the fos­sil for 150 mil­lion years is ex­tra­or­di­nary, Man­ning said.

To­geth­er these chem­i­cal traces are believed to indicate the feath­er was light in col­or, with ar­eas of darker pig­menta­t­ion along one edge and on the tip. Scans of a sec­ond fos­silized Ar­chae­op­ter­yx, known as the Ber­lin coun­ter­part, re­vealed that its cov­ert feath­ers had the same pig­menta­t­ion pat­tern, Man­ning said.


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The feathers of Archaeopteryx, a famous fossil linking dinosaurs and birds, were not all black, but rather patterned—light-colored with a dark edge and tip, a new chemical analysis indicates. The findings, overturning previous thinking about the feather hues, came from X-ray experiments at the U.S. Department of Energy’s SLAC National Accelerator Laboratory. There, scientists found chemical traces of the original dinobird and its pigments in the rock that entombed it an estimated 150 million years ago. “This is a big leap forward in our understanding of the evolution of plumage,” said Phillip Manning, a paleontologist at the University of Manchester, U.K. and lead author of the report in the June 13 issue of the Journal of Analytical Atomic Spectrometry. Only 11 Archaeopteryx specimens have been found, the first consisting of just one feather. Until a few years ago, researchers thought all the bones and tissues of the original animal would have been replaced by minerals during fossilization, leaving no chemical traces behind. But two recently developed methods have turned up more information about the dinobird and its plumage. The first is the discovery of melanosomes—microscopic structures containing pigment—in fossils. A team led by researchers at Brown University in Rhode Island announced last year that an analysis of melanosomes in the Archaeopteryx feather specimen showed that the feather was black. They identified the feather as a covert—a type of feather that covers the primary and secondary wing feathers—and said its heavy pigmentation may have strengthened it against the wear and tear of flight, as it does in modern birds. However, that study examined melanosomes from just a few locations in the fossilized feather, said SLAC’s Uwe Bergmann. “It’s actually quite a beautiful paper,” he said, “but they took just tiny samples of the feather, not the whole thing.” The second is a method Bergmann, Manning and Roy Wogelius of the University of Manchester developed for rapidly scanning entire fossils and analyzing their chemistry with an X-ray beam at SLAC’s Stanford Synchrotron Radiation Lightsource. Over the past three years, they led a team that used this method to discover chemicals left by the dinobird’s bones and feathers in the surrounding rock, as well as pigments from the fossilized feathers of two of the first known birds. This let them recreate the plumage pattern of a bird that lived more than 120 million years ago. In the latest study, the team scanned the entire fossil of the first Archaeopteryx feather with the X-ray beam. They found trace metals associated with pigments and organic sulfur compounds that could only have come from the animal itself. The fact that these compounds have been preserved in the fossil for 150 million years is extraordinary, Manning said. Together these chemical traces show that the feather was light in color, with areas of darker pigmentation along one edge and on the tip. Scans of a second fossilized Archaeopteryx, known as the Berlin counterpart, revealed that its covert feathers had the same pigmentation pattern, Manning said.