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Molecular analysis of anchiornis feathers gives traces to the origin of the aircraft



An Anchiornis sample from Jianchang, western Liaoning. The sampling site is marked with a red box. Credit: Yanhong Pan

An international research group has performed molecular analysis of fossil feathers from a small, feathered dinosaur from the law. Their research could help scientists find out when feathers developed flight capacity during the transition to dinosaur / bird.


Anchiornis was a small, feathered, four-winged dinosaur who lived in what is now China about 1

60 million years ago – nearly 10 million years before Archeopteryx, the first recognized bird. A team of researchers from Nanjing Department of Geology and Paleontology, North Carolina State University and the University of South Carolina analyzed Anchiornis feathers to see how they differ at the molecular level of the younger fossil birds and modern birds.

"Modern bird feathers consist primarily of beta-keratin (β-keratin), a protein also found in the skin, claws and beak of reptiles and birds. Spring differs from these other β-keratin-containing tissues because the spring protein is modified on a way that makes them more flexible, "says Mary Schweitzer, a professor of life sciences at the NC state with a joint agreement in North Carolina's Faculty of Science and co-author of a paper describing the research. 19659005] "At some point during the development of feathers, one of the β-keratin genes underwent a deletion event, making the resulting protein slightly smaller. This deletion changed the feather biophysics to something more flexible – a flight requirement. find out when and in which organisms a deletion event occurred, we will get a better understanding of when the flight evolved during the transition from dinosaurs to birds. "

The researchers, led by Yanhong Pan, a visiting researcher from the Nanjing Institute, examined fossilized feathers from Anchiornis using high-resolution electron microscopy as well as several chemical and immunological techniques for determining the molecular composition of the feathers. They did the same with other feathers from the mesozoic and kenozoic erases as well as other β-keratin tissues, which are not expected to show this deletion, compared to the results with modern bird feathers and tissues.

They found that Anchiornis feathers consisted of both β-keratins and alpha-keratins (α-keratins), a protein having all terrestrial vertebrates, including mammals. This was surprising because α-keratin is present in only small amounts in modern feathers. In addition to co-expressing both keratin proteins, Anchiornis had already undergone the deletion event which sets feathers apart from other tissues.

"Molecular clocks, which scientists use as benchmarks for evolutionary and genetic divergence, predict that the erosion and hence functional flight spring evolved about 145 million years ago," says Schweitzer. " Anchiornis is millions of years older, but has shortened protein form. This work shows that we can utilize molecular fossil data for rotational molecules and improve their accuracy – we can begin to set timing on genetic events in the dinosaur bird transition via the absence or presence of these two keratins. The data also gives us more information on how feathers evolved to enable flight. "

The work is apparent from Procedures of the National Academy of Sciences (" Molecular evolution of feathers with direct evidence from fossils "). Pan is the lead author. Wenxia Zheng and Elena Schroeter of NC State and Roger Sawyer of the University of South Carolina also contributed to the work, which was partly supported by the National Science Foundation and the Packard Foundation.


Explore further:
Keratin and melanosomes preserved in 130 million year old bird fossils

More Information:
Yanhong Pan et al., "The Molecular Evolution of Fossils with Direct Fossils by Fossils" PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1815703116

Journal reference:
Attempts by the National Academy of Sciences

Available by:
North Carolina State University


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