Feathered dino flew, not glided

As pretty much every school child can attest, Archaeopteryx was a feathered dinosaur, a curious beast with wings, dating from the late Jurassic period around 160 million years ago.

The first Archaeopteryx fossil was found 150 years ago and ever since then a very particular debate has ranged among palaeontologists – could it fly, or did it merely glide? It’s a question with substantial ramifications for understanding the evolution of flight.

Now, a team of researchers led by Dennis Voeten of the European Synchrotron Radiation Facility in France appears to have brought the discussion to an end. Archaeopteryx flew, if only perhaps to get off the ground quickly to escape predators or get over an obstacle.

To make the finding the team used an imaging technique called propagation phase-contrast synchrotron X-ray microtomography (PPC-SRμCT) to create extremely detailed cross-sections of the humerus and ulna bones of three Archaeopteryx fossils. These were then compared to similar images taken of 69 other species, including extinct pterosaurs and living birds.

The researchers found that the fossil bones had been densely packed with blood vessels, indicating that they required a lot of energy when in use. This and some other measures, such as bone thickness, indicates that the dinosaurs definitely flew.

How often and for how long they were in the air are questions still to be answered. Drawing firm conclusions is difficult because the bone structures show that Archaeopteryx had a flight stroke very different to that of modern birds.

However, the scientists write, certain inferences are possible. Based on comparisons with the other specimens imaged, the dinosaur had similarities with “birds that incidentally employ flapping flight to evade predators or cross physical barriers”.

Importantly, they note, the research shows that Archaeopteryx actively used its wings to get off the ground.

The research is published in the journal Nature Communications.