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Winged dinosaur Archaeopteryx dressed for flight

Wednesday, 25 January 2012

Paleontologists have long thought that Archaeopteryx fossils, including this one discovered in Germany, placed the dinosaur at the base of the bird evolutionary tree. Credit: Humboldt Museum für Naturkunde Berlin

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 color 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.

Fit for flight from Brown PAUR on Vimeo.

The team also learned from its examination that Archaeopteryx feather structure is identical to that of living birds, a discovery that shows modern wing feathers had evolved as early as 150 million years ago in the Jurassic period. The study, which appears in Nature Communications, was funded by the National Geographic Society and the U.S. Air Force Office of Scientific Research.

"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).