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August 03, 2010

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Some dino feather colors identified

Jan. 27, 2010
Courtesy Bristol University
and World Science staff

The colour of some feath­ers on di­no­saurs and early birds has been iden­ti­fied for the first time, re­ports a pa­per pub­lished in the re­search jour­nal Na­ture this week.

An anal­y­sis con­clud­ed that Sino­saur­op­ter­yx, a much small­er rel­a­tive of Ty­ran­no­saur­us rex, sported bris­tles that were pre­cur­sors of feath­ers in al­ter­nate or­ange and white rings down its tail. And the early bird Con­fu­ciu­sor­nis had patches of white, black and or­ange-brown colour­ing, sci­en­tists said. Fu­ture work is ex­pected to al­low pre­cise map­ping of colours and pat­terns across the whole bird.

Fos­sil of the the­ro­pod di­no­saur Si­no­saur­op­ter­yx. (Pho­to © The Nan­jing In­sti­tute)

“Our re­search pro­vides ex­tra­or­di­nary in­sights in­to the or­i­gin of feath­ers. In par­tic­u­lar, it helps to re­solve a long-stand­ing de­bate about the or­i­ginal func­tion of feath­ers – wheth­er they were used for flight, in­sula­t­ion, or dis­play. We now know that feath­ers came be­fore wings, so feath­ers did not or­i­ginate as flight struc­tures,” said pa­le­on­tol­o­gist Mike Ben­ton at the Univers­ity of Bris­tol, U.K., one of the sci­en­tists.

“We there­fore sug­gest that feath­ers first arose as agents for colour dis­play and only lat­er in their ev­o­lu­tion­ary his­to­ry did they be­come use­ful for flight and in­sula­t­ion.”

The re­search­ers from the U.K., Chi­na and Ire­land re­ported iden­ti­fy­ing two kinds of melanosomes, or cel­lu­lar struc­tures, in the feath­ers of many birds and di­no­saurs from north­east­ern Chi­na’s fa­mous Je­hol fos­sil beds.

Melanosomes are colour-bearing com­part­ments with­in the cells of feath­ers and hair in mod­ern birds and mam­mals, giv­ing black, grey, and tones such as or­ange and brown. Be­cause melanosomes are part of the tough pro­tein struc­ture of the feath­er, they can sur­vive for hun­dreds of mil­lions of years.

A re­con­struc­tion of Si­no­saur­op­ter­yx. (Pho­to © Chu­ang Zhao and Li­da Xing)

The find­ings con­firm a widely ac­cept­ed the­o­ry that birds evolved through from a long line of meat-eating di­no­saurs called theropods, which in­clude T. rex, the re­search­ers said. It al­so shows, they added, that mod­ern birds’ un­ique as­sem­blage of traits – feath­ers, wings, light skel­e­ton, en­hanced me­tab­o­lism, en­larged brain and vis­u­al sys­tems – evolved step-by-step over some 50 mil­lion years of di­no­saur ev­o­lu­tion, through the Ju­ras­sic and Cre­ta­ceous pe­ri­ods.

“These disco­veries open up a whole new ar­ea of re­search,” said Ben­ton, “al­low­ing us to ex­plore as­pects of the life and be­hav­iour of di­no­saurs and early birds that lived over 100 mil­lion years ago.

“Fur­ther­more, we now know that the sim­plest feath­ers in di­no­saurs such as Sino­saur­op­ter­yx were only pre­s­ent over lim­it­ed parts of its body – for ex­am­ple, as a crest down the mid­line of the back and round the tail.” They might have al­so had a lim­it­ed func­tion in heat regula­t­ion, he added.

“Feath­ers are key to the suc­cess of birds,” he con­tin­ued. “We can now dis­sect their ev­o­lu­tion­ary his­to­ry in de­tail and see how each feath­er type – and the fi­ne de­tail of feath­er struc­ture – was ac­quired through time. This will link with cur­rent work on how the ge­nome con­trols feath­er de­vel­op­ment.”

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Homepage image: Artist's reconstruction of Si­no­saur­op­ter­yx (© Jim Robins)

 

The colour of some feathers on dinosaurs and early birds has been identified for the first time, reports a paper published in the research journal Nature this week. An analysis concluded that Sinosauropteryx, a relative of Tyrannosaurus rex, sported bristles that were precursors of feathers in alternate orange and white rings down its tail. And the early bird Confuciusornis had patches of white, black and orange-brown colouring, scientists said. Future work is expected to allow precise mapping of colours and patterns across the whole bird. “Our research provides extraordinary insights into the origin of feathers. In particular, it helps to resolve a long-standing debate about the original function of feathers – whether they were used for flight, insulation, or display. We now know that feathers came before wings, so feathers did not originate as flight structures,” said paleontologist Mike Benton at the University of Bristol, U.K., one of the scientists. “We therefore suggest that feathers first arose as agents for colour display and only later in their evolutionary history did they become useful for flight and insulation.” The researchers from the U.K., China and Ireland reported identifying two kinds of melanosomes, or cellular structures, in the feathers of many birds and dinosaurs from northeastern China’s famous Jehol fossil beds. Melanosomes are colour-bearing compartments within the cells of feathers and hair in modern birds and mammals, giving black, grey, and tones such as orange and brown. Because melanosomes are part of the tough protein structure of the feather, they can survive for hundreds of millions of years. The findings confirm a widely accepted theory that birds evolved through from a long line of meat-eating dinosaurs called theropods, which include T. rex, the researchers said. It also shows, they added, that modern birds’ unique assemblage of traits – feathers, wings, light skeleton, enhanced metabolism, enlarged brain and visual systems – evolved step-by-step over some 50 million years of dinosaur evolution, through the Jurassic and Cretaceous periods. “These discoveries open up a whole new area of research”, said Benton, “allowing us to explore aspects of the life and behaviour of dinosaurs and early birds that lived over 100 million years ago. “Furthermore, we now know that the simplest feathers in dinosaurs such as Sinosauropteryx were only present over limited parts of its body – for example, as a crest down the midline of the back and round the tail.” They might have also had a limited function in heat regulation, he added. “Feathers are key to the success of birds,” he continued. “We can now dissect their evolutionary history in detail and see how each feather type – and the fine detail of feather structure – was acquired through time. This will link with current work on how the genome controls feather development.”