L'archaeopteryx pouvait-il voler?



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The feathered dinosaur Archaeopteryx is sometimes called the “first bird” because the winged creature was the first to show an evolutionary link between birds and reptiles. But could it fly?

Paleontologists have fiercely debated this question for decades. Despite its winged form, it’s been unclear whether the animal could get airborne via its own power. Did Archaeopteryx primarily glide down from treetops? Did it flap its wings to escape grounded predators? Or did it do something different altogether?

Now, analysis of the creature’s forelimb bones finds that their structure closely resembles that of wing bones in today’s quails and pheasants, species that can fly for short bursts.

The discovery, published in Nature Communications on Tuesday, strengthens the case that Archaeopteryx could indeed take to the air.

(...) In the years since, Archaeopteryx has been the subject of intense study, including fierce debate over its flight capabilities.

This tumultuous back-and-forth is in part due to worrying about what the fossil animal is missing—“comparing Archaeopteryx to a living bird, and commenting on what it does not have” 

(...) For instance, modern flying birds have breastbones with keels, extensions where powerful breast muscles can anchor and drive the birds’ downward flight stroke. Archaeopteryx fossils haven’t been found with bony breastbones, but (...) it’s possible these structures were made of cartilage and weren’t easily fossilized.

(...) “A lot of research had indirect evidence for flight, but it was never really substantiated,” says ESRF paleontologist Dennis Voeten, the new study’s lead author. “We decided to approach it from the other way around: We tried to actively find indicators of flight in the skeleton, rather than identify conditions that may or may not have enabled flight.”

(...) The team then compared Archaeopteryx’s stats to those of 55 modern birds, two crocodilians, and two species of pterosaurs, the winged reptiles that lived alongside dinosaurs. Archaeopteryx’s measurements best resembled those of living birds that fly for short bursts, such as quails and pheasants.

What’s more, Voeten found that like modern birds, the Archaeopteryx skeletons had been rich with blood vessels. The discovery suggests that Archaeopteryx’s growth trends and metabolism resembled those of modern birds more than previously thought.

(...) The researchers also caution that, based on their data, Archaeopteryx couldn’t perform the modern avian flight stroke.

(...) Animals like Archaeopteryx “didn't need huge chest muscles and big breastbones, but found other ways to power themselves into the sky,” says Brusatte. “And that probably means even some non-bird dinosaurs that hadn't quite yet crossed that line into birds may have been able to flap a little bit.”

For Clarke, ancient variation is to be expected. In the late Jurassic, evolution was in its sketching phase, as a menagerie of feathered dinosaurs haltingly took to the air. Only then could evolution refine flight to what it is today.



 

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