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According to an analysis of hundreds of preserved bird specimens from museum collections around the world, there is a specific set of feather rules behind the power of flight.
These newly discovered rules allow scientists to better predict which dinosaurs could also fly.
“Theropod dinosaurs, including birds, are one of the most successful vertebrate lineages on our planet.” says Field Museum of Natural History paleontologist Jingmai O’Connor. “One of the reasons they are so successful is their flight. One of the other reasons is probably their feathers, because they have very versatile structures.”
Their new data could resolve some long-standing paleontological debates about whether Flight evolved in dinosaurs on more than one occasion.
By examining the wing feathers of 346 different species of birds from museums around the world, Field Museum of Natural History ornithologist Yosef Kiat discovered an interesting trend. From the smallest hummingbird to the fiercest eagle, all flying birds had 9 to 11 asymmetrical flight feathers called primaries.
But the number of primary feathers in flightless birds varied greatly. Emus lack them. completely, while the penguins imagine themselves with 40.
“It’s really surprising that with so many flight styles that we can find in modern birds, they all share this trait of having between nine and eleven primary feathers.” says Kiat. “And I was surprised that no one seems to have found this before.”
The number of primaries, together with the symmetry of the feathers and the proportions of the wings accurately reflect the flight capacity of all known modern birds.
By looking at fossils up to 160 million years old, the researchers identified which bird ancestors shared these traits and were therefore likely to be able to fly. Of 35 different species of extinct birds, Kiat and O’Conner identified some that had the right feathers for flight and others that did not.
Possible flyers include Archeopteryx, considered one of the first bird-like animals. While there is debate about the true relationship between Archeopteryx and birds, tiny four-winged dinosaurs called Microraptors It also had these characteristics, despite not being directly related to birds.
“Scientists have only recently realized that birds are not the only flying dinosaurs,” Explain O’Connor.
Strangely, Caudipteryx It had the correct number of primary feathers but they were almost completely symmetrical.ethical, “almost certainly” ruling out the flight. thThe researchers speculate that Caudipteryx The ancestor could probably fly, but the genus had since lost this ability.
“Our results here seem to suggest that flight only evolved once in dinosaurs,” state O’Connor.
Their analysis indicates that the anatomy necessary for flight evolved in a species ancestral to all of these pennaraptoran groups before they diversified. Something like Caudipteryx, stopped flying from the beginning. those like Microraptors they retained their flight but ended up being part of an evolutionary dead end. Others became modern birds.
Kiat and O’Connor point out that claims suggesting that flight evolved multiple times in dinosaurs were based solely on skeletal data.
“We maintain that it is impossible to evaluate the flight potential of non-avian pennaraptorans without examining the structure of the feathers that form the wing,” they say. write in your newspaper.
They believe we are still missing the early stages of wing evolution in our fossil records, so this is unlikely to be the last word in the debate.
This research was published in PNAS.