If you have been to gaze skyward in the late Cretaceous, you may catch a glimpse of surreal flying giants with wingspans that rival small planes. This supersized group of pterosaurs, often called azhdarchids, included species that measured 33 ft between wingtips, which made them the largest animals that ever took to the air.
The excessive dimensions of azhdarchids increase tantalizing questions, equivalent to how they carried giant prey with out breaking their lengthy necks, or how animals the measurement of giraffes effortlessly soared above their dinosaur family on the floor.
Cariad Williams, a Ph.D. pupil at the University of Illinois at Urbana-Champaign, hoped to shed some gentle on these questions with the assist of an azhdarchid specimen from the Kem Kem fossil beds of Morocco. She used a CT scan to review fossils from the animal’s neck.
“We just couldn’t believe the structure that we found inside,” Ms. Williams stated.
The outcomes, published on Wednesday in the journal iScience, shocked Ms. Williams and her colleagues. The animal’s neck was revealed to be scaffolded by a novel and sophisticated community of helical struts connecting a central neural tube to the vertebra wall like the spokes of a bicycle. It was a construction that has no parallel elsewhere in the animal kingdom.
This unprecedented peek into an azhdarchid neck helps to fill a few of the persistent gaps in our information of their anatomy and conduct. Pterosaurs, like birds, developed extraordinarily fragile and light-weight skeletons to optimize their flight skills; these qualities additionally trigger them to be underrepresented in the fossil report as a result of their bones simply break aside.
The Kem Kem web site is amongst the solely place in the world the place comparatively intact azhdarchid fossils may be discovered. The Moroccan fossil beds protect a lush river system that existed about 100 million years in the past, attracting Cretaceous sharks, giant predatory dinosaurs like Spinosaurus and Carcharodontosaurus, in addition to azhdarchids.
Ms. Williams and her colleagues tentatively recognized their specimen as an Alanqa pterosaur. While it’s troublesome to estimate its actual dimensions, the azhdarchid most likely had a five-foot-long neck and a wingspan that measured between 20 to 26 ft.
A biomechanical evaluation of the intricate construction of the neck revealed that the spokelike filaments bolstered the vertebrae towards the pressures of catching and carrying heavy prey. According to the staff’s calculations, the addition of solely 50 struts elevated by 90 p.c the weight that they may bear with out buckling, enabling this specific specimen to hold a great deal of as much as 24 kilos, which Ms. Williams referred to as “really impressive.”
“They were using less energy to optimize their strength in their neck to be able to lift the prey,” she stated.
The uncommon adaptation could have features past looking and feeding, equivalent to “neck ‘bashing,’ an intermale rivalry behavior seen in giraffes” or as a option to cope with the “shearing forces associated with large skulls being buffeted by strong winds during flight or while on the ground,” in line with the examine. Ms. Williams and her colleagues plan to observe up on their findings by scanning different azhdarchid vertebrae to evaluate whether or not the spoke construction is widespread.
David Hone, a paleontologist at Queen Mary, University of London, who was not concerned in the examine, stated the new analysis gives a “nice confirmation” of the mechanical soundness of azhdarchid vertebrae.
“It’s a very neat finding that there is this weird arrangement of struts and that this is about the minimum possible to strengthen the bone,” he stated. “But it’s also not much of a surprise as we know azhdarchids had incredibly reduced bones and were extraordinarily light for their size.”
“What we really need for azhdarchids is a well-preserved 3-D skeleton,” Dr. Hone concluded. “We are working from either flattened fossils or very incomplete specimens, which makes it hard to work out even a lot of basics.”