Winged dinosaur Archaeopteryx had black feathers

London, Jan 25 (ANI): Archaeopteryx, a 150 million-year-old winged dinosaur, had black feathers on its wings that were structurally similar to that of living birds, indicating that modern wing feathers evolved in the Jurassic period, a new study has revealed.

Since its discovery 150 years ago, scientists have puzzled over whether the winged dinosaur Archaeopteryx represents the missing link in birds' evolution to powered flight. Much of the debate has focused on the iconic creature's wings and the mystery of whether - and how well - it could fly.

Some secrets have been revealed by an international team of researchers led by Brown University. Through a novel analytic approach, the researchers have determined that a well-preserved feather on the raven-sized dinosaur's wing was black.

The colour and parts of cells that would have supplied pigment are evidence the wing feathers were rigid and durable, traits that would have helped Archaeopteryx to fly.

"If Archaeopteryx was flapping or gliding, the presence of melanosomes [pigment-producing parts of a cell] would have given the feathers additional structural support," said Ryan Carney, an evolutionary biologist at Brown and the paper's lead author.

"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, a few years after the publication of Charles Darwin's On the Origin of Species. Paleontologists have long been excited about the fossil and other Archaeopteryx specimens, thinking they place the dinosaur at the base of the bird evolutionary tree.

The traits that make Archaeopteryx an evolutionary intermediate between dinosaurs and birds, scientists say are the combination of reptilian features (teeth, clawed fingers, and a bony tail) and avian features (feathered wings and a wishbone).

Carney, with researchers from Yale University, the University of Akron, and the Carl Zeiss laboratory in Germany, analyzed the feather and discovered that it is a covert, so named because these feathers cover the primary and secondary wing feathers birds use in flight.

After two unsuccessful attempts to image the melanosomes, the group tried a more powerful type of scanning electron microscope at Zeiss, where the group located patches of hundreds of the structures still encased in the fossilized feather.

"The third time was the charm, and we finally found the keys to unlocking the feather's original color, hidden in the rock for the past 150 million years," said Carney, a graduate student in the Department of Ecology and Evolutionary Biology, studying with Stephen Gatesy.

The team measured the length and width of the sausage-shaped melanosomes, roughly 1 micron long and 250 nanometers wide. To determine the melanosome's colour, Akron researchers Matthew Shawkey and Liliana D'Alba statistically compared Archaeopteryx's melanosomes with those found in 87 species of living birds, representing four feather classes: black, gray, brown, and a type found in penguins.

"What we found was that the feather was predicted to be black with 95 percent certainty," Carney said.

Next, the team sought to better define the melanosomes' structure. For that, they examined the fossilized barbules - tiny, rib-like appendages that overlap and interlock like zippers to give a feather rigidity and strength.

The barbules and the alignment of melanosomes within them, Carney said, are identical to those found in modern birds.

What the pigment was used for is less clear. The black colour of the Archaeopteryx wing feather may have served to regulate body temperature, act as camouflage or be employed for display. But it could have been for flight, too.

The study has been published in Nature Communications. (ANI)