Large pterosaurs exhibited different flight styles

September 6 () –

Some species of pterosaurs flew by flapping their wings, while others soared like vultures, according to a new study published in Journal of Vertebrate Paleontology.

There has long been debate over whether the largest pterosaurs could fly. Now, “Remarkable” and “rare” three-dimensional fossils of two different species of large azhdarchoid pterosaurs (including one new to science) have allowed scientists to hypothesize that Not only could larger pterosaurs fly, but their flight styles may have differed as well.

A study led by experts from the University of Michigan and colleagues in Jordan and Saudi Arabia details how these fossils, dating from the late Cretaceous period (approximately 72 to 66 million years ago), were remarkably preserved in three dimensions. in two different sites preserving a coastal environment on the Afro-Arabia margin, an ancient landmass that included both Africa and the Arabian Peninsula.

The research team used high-resolution computed tomography (CT) scans to analyze the internal structure of the wing bones.

“The excavation team was extremely surprised to find pterosaur bones preserved in three dimensions, This is a very rare occurrence” explains lead author Dr. Kierstin Rosenbach of the Department of Earth and Environmental Sciences at the University of Michigan.

“Since pterosaur bones are hollow, they are very fragile and are more likely to be found flattened like a pancake, if they are preserved at all. Because 3D preservation is so rare, we don’t have much information about what pterosaur bones look like inside, so I wanted to scan them with a CT scan. It was entirely possible that nothing inside had been preserved or that the CT scans hadn’t preserved anything. were not sensitive enough to differentiate fossil bone tissue from the surrounding matrix“, he explained.

Fortunately, however, what the team discovered was “remarkable,” with “fascinating internal structures that were not only preserved, but could also be seen on the CT scan.”

TEN METERS WINGSPAN

Newly collected specimens of the already known giant pterosaur, Arambourgiania philadelphiae, confirm its 10-meter wingspan and provide the first details of its bone structure. CT images revealed that the inside of its humerus, which is hollow, contains a series of ridges that spiral up and down the bone.

This resembles the structures inside the wing bones of vultures. The spiral ridges are thought to resist the torsional loads associated with gliding (sustained powered flight that requires wing flapping for takeoff and maintenance).

The other specimen analyzed was the Inabtanin alarabia, new to science, which had a wingspan of five meters. The team named it after the place where it was excavated, near a large grape-colored hill called Tal Inab. The generic name combines the Arabic words “inab,” meaning grape, and “tanin,” meaning dragon. “Alarabia” refers to the Arabian Peninsula.

Inabtanin is one of the most complete pterosaurs ever recovered from Afro-Arabia, and CT scans revealed that the structure of its flight bones was completely different from that of Arambourgiania.

The interior of the flight bones was crisscrossed by a strut arrangement which match those found in the wing bones of modern flapping birds.

This indicates that it was adapted to withstand the bending loads associated with flapping flight, so it is likely that Inabtanin flew in this manner, although this does not exclude the occasional use of other flight styles as well.