The mystery of how pterosaurs were able to fly through the air with their long giraffe-like necks has finally been solved. Scientists have long wondered how their necks didn’t snap while carrying the weight of their incredibly large heads and the answer was in their oddly composed vertebrae.
Pterosaurs showed up around 215 million years ago during the Triassic Period and survived for approximately 150 million years before going extinct around the end of the Cretaceous Period. Since they had a wingspan that could reach 12 meters (39 feet) and their necks were about 2.5 meters in length (8.2 feet) with a head that measured about 1.5 meters (4.9 feet), it’s astonishing to think they could fly.
It was previously thought that they had tube-within-tube features in their neck, but new CT scans have revealed that their vertebrae resembled the spokes of a bicycle wheel. The bones had several skinny rod-like tissues called trabeculae that were in a corkscrew-like shape that crossed over each other. (A picture of the scanned bone can be seen here.)
That bone structure was how they could fly and move their heads without their necks snapping. Furthermore, their spoke-like trabeculae allowed their necks to carry the extra weight by about 90%. To explain this further, with just 50 struts, they could have carried as much as 24 extra pounds without their necks buckling. “They were using less energy to optimize their strength in their neck to be able to lift the prey,” noted Cariad Williams, who is a Ph.D. student at the University of Illinois at Urbana-Champaign and an author of the study.
The specimen they studied was an Alanqa from the azhdarchid pterosaur family that was unearthed at the Kem Kem fossil beds in Morocco. The researchers estimated that this specific specimen may have had a wingspan of between 20 and 26 feet (6 to 8 meters) as well as a five-foot-long neck.
Professor David Martill, who is another author of the study, explained how the preserved remains allowed them to come to this conclusion, “What was utterly remarkable was that the internal structure was perfectly preserved,” adding, “As soon as we saw the intricate pattern of radial trabeculae, we realized there was something special going on. As we looked closer, we could see that they were arranged in a helix travelling up and down the vertebral tube and crossing each other.”
The researchers’ next step is to analyze additional azhdarchid vertebrae in order to know for sure whether the spoke-like structure were present in other pterosaurs.
The study was published in iScience where it can be read in full.