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This Dinosaur's Feathers are an evolutionary mystery



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An illustration of the red-headed Anchiornis . Matt Martyniuk / CC BY 3.0

Meet Anchiornis . A one-foot-tall, four-winged, 1

60-million-year-old redhead from present-day China, this dinosaur is a precursor to modern birds, down to its chicken-like feet. Like many other dinosaurs found in China, it also had "boatloads of feathers," says Mary Schweitzer, a paleontologist at North Carolina State University. The first bird, Archeopteryx, emerged nearly 10 million years later, but Anchiornis 's Wealth of Feathers.

Flight is an "expensive" capability, says Schweitzer. There has been a lot of "evolutionary reason" to justify it, so the discovery of feathered dinosaurs did not automatically indicate that this species could fly. New research published in the Proceedings of the National Academy of Sciences set out to determine whether Anchiornis could.

Anchiornis Anchiornis feathers revealed the presence of both beta-keratin (β-keratin) and alpha-keratin (ɑ-keratin) in these dinosaurs' plumages , This co-expression showed what a difference 10 million years can make: bird-keratin, and for good reason. Its filaments are about 10 nanometers in diameter, says Schweitzer, a co-author of the new study, while β-keratin's filaments are only about three nanometers across. Hair, skin, and nails.

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Anchiornis specimen evaluated in the new study. Courtesy WANG Xiaoli

But it's not that simple. The particular kind of β-keratin found in Anchiornis 's feathers, says Schweitzer, is consistent with that found in modern flying feathers. One β-keratin is not just like another: At some point, she says, a "deletion event" took place in which the protein had a chunk cut off it, losing amino acids that made it more brittle. The keratin became more flexible, and thus more conducive to flight. Somehow, Anchiornis sports both the post-deletion β-keratins of its flying descendants along with the ɑ-keratins reserved for those of us stranded on land and in water.

How could Anchiornis fly? It's not really clear, and if so, it's not really clear what that would have looked like. What the study does tell us, is that beta-keratin's pro-flight deletion event took place earlier than previously estimated. Molecular fossil data, Schweitzer in the release, can help "root molecular clocks and improve their accuracy," and can help get more complete, if more complicated, sense of feathers evolved to fly.

to majestic flight, to defensive slime, it really is all in the keratin.


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