'Flying dinosaurs wore plumage of black feathers'
Washington: A winged dinosaur long thought to be a "missing link" in the evolution of birds may have been adorned with black feathers just like modern birds, scientists have found.
The raven-size creature called Archaeopteryx lived about 150 million years ago in what is now Bavaria in Germany. First unearthed 150 years ago, the fossil of this carnivore, with its blend of avian and reptilian features, seemed an iconic evolutionary link between dinosaurs and birds.
The structures that held the black pigment may have strengthened wing feathers, perhaps helping Archaeopteryx fly, the scientists believe.
An international team claimed that they found conclusive proof that the creature's wings were black, and that the rigid wing feathers could have helped the creature flap and glide.
Whether or not it could actually take off under its own power, however, remains a mystery
"Being able to reconstruct the colours of feathers can help us gain more knowledge about the organisms and more responsibly reconstruct what they looked like," study author Ryan Carney, an evolutionary biologist at Brown University, told LiveScience.
The colour-generating structures within the creature's feather, known as melanosomes, "would have given the feathers additional structural support", Carney said. "This would have been advantageous during this early evolutionary stage of dinosaur flight."
The Archaeopteryx feather was discovered in a limestone deposit in Germany in 1861. After two unsuccessful attempts to pinpoint any melanosomes within the feather, the investigators tried a more powerful type of scanning electron microscope.
"The third time was the charm, and we finally found the keys to unlocking the feather's original colour, hidden in the rock for the past 150 million years," Carney said.
The researchers, who detailed their findings in the journal Nature Communications, located patches of hundreds of melanosomes encased within the fossil.
The sausage-shape melanosomes were about 1 millionth of a meter long and 250 billionths of a meter wide that is, about one-hundredth the diameter of a human hair in length and less than a wavelength of visible light in width.
To determine the colour of these melanosomes, researchers compared the fossilised structures with those found in 87 species of living birds that represented four classes of feathers- black, gray, brown and ones found in penguins, which have unusually large melanosomes compared with other birds.
"What we found was that the feather was predicted to be black with 95 percent certainty," Carney said.
To better pin down the structure of the feather, they analysed its barbules tiny, riblike appendages that overlap and interlock like zippers to give a feather rigidity and strength.
This analysis revealed the feather is a covert, one that covers the primary wing feathers that birds use in flight. Its feather structure is identical to that of living birds, suggesting "that completely modern bird feathers evolved as early as 150 million years ago," Carney said.
Colour may serve many functions in modern birds, and it remains unclear what use or uses this pigment had in Archaeopteryx, the scientists added.