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An Asteroid Wiped Out Dinosaurs. Did It Help Birds Flourish?

Sixty-six million years ago, an asteroid slammed into the Gulf of Mexico. The catastrophe led to the extinction of as many as three-quarters of all species on Earth, including dinosaurs like Tyrannosaurus rex. But some flying feathered dinosaurs survived, and eventually evolved into the more than 10,000 species of birds living today, including hummingbirds, condors, parrots and owls.

Based on the fossil record, paleontologists have long argued that the asteroid’s impact was followed by a big pulse of bird evolution. The mass extinction of other animals may have eliminated a lot of competition for the birds, giving them the chance to evolve into the remarkable diversity of species that fly around us today.

But a new study on the DNA of 124 bird species challenges that idea. An international team of scientists found that birds began diversifying tens of millions of years before the fateful collision, suggesting that the asteroid had no major effect on bird evolution.

An owl, known as Flaco, in New York City.Credit…David Lei/David Lei, via Associated Press
Emus in Hamilton, Mont.Credit…Tony Demin for The New York Times

“I imagine this will ruffle a few feathers,” said Scott Edwards, an evolutionary biologist at Harvard and one of the study’s authors. The research was published on Monday in the Proceedings of the National Academy of Sciences.

Dinosaurs evolved primitive feathers at least 200 million years ago, not for flight but most likely for insulation or a mating display. In one lineage of small bipedal dinosaurs, those feathers became more complex and then ultimately took the creatures into the air as birds. How feathers turned into wings for flight is still debated. But once birds evolved, they diversified into a variety of forms, many of which became extinct when the asteroid plunged the Earth into a yearslong winter.

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