At what age could pterosaurs fly? Up to now, this question has been a contentious issue in science. Using wing measurements from several fossils, researchers have now modeled how and when the young animals were likely to be able to take to the skies. According to this, young pterosaurs were likely to be able to fly shortly after hatching. In contrast to adult individuals, however, their wing shape was less designed for long-haul flights. Instead, they were presumably more agile and could move more easily in densely vegetated surroundings.
Pterosaurs were a group of flying dinosaurs that lived from the Triassic to the Cretaceous Period, 228 to 66 million years ago. They were the first vertebrates to be able to fly on their own. At what point in their lives young animals acquired this ability, however, has so far been unclear. Some researchers assumed that the pterosaurs only became airworthy late in their adolescence and that they had to be at least half the size of adults. Others suspected that young pups could not fly, but could glide.
Comparison of the wing dimensions
A team led by Darren Naish from the University of Southampton in Great Britain has now checked these hypotheses and has come to the conclusion: Although young pterosaurs were indeed excellent gliders, they were probably able to get in on their own just a few hours to days after hatching raise the skies. “The earliest stages in the life of the pterosaurs were shrouded in mystery for a long time, which is mainly due to the rarity or the lack of eggs and embryos in most taxa, but also to the difficulty of distinguishing hatchlings from small adults,” the researchers explain.
For their analysis, Naish and his colleagues resorted to fossils of the pterosaur species Pterodaustro guinazui and Sinopterus dongi, which were certainly derived from hatchlings and embryos. Using their wing dimensions, the researchers modeled the extent to which the young animals were presumably able to fly or glide. The strength of the humerus in the wings is also crucial for flight under its own power. Therefore, they also compared the humerus of three hatchlings with those of 22 adult pterosaurs.
Excellent in planing and flying
The result: “The analysis of the wing shape suggests that young pterosaurs were outstanding gliders,” the authors write. “Newly hatched pterosaurs show the ability to long-term, long-range gliding flights that far exceed the gliding ranges of experienced gliders living today.” The reason for this is that the wing area of the young pterosaurs was particularly large in relation to body size and weight. Their humerus also shows that they could not only glide, but also fly under their own power: “The humerus of the newly hatched pterosaurs are – in relation to their body weight – among the strongest of all pterosaurs,” the researchers report.
Based on their results, Naish and his colleagues believe it is likely that pterosaurs have already hatched with the ability to fly. As is typical for pterosaurs, the wings of the young are already relatively long and narrow – but less pronounced than in adult individuals. “Larger individuals achieved higher flight speeds and had better lift and improved gliding abilities,” the researchers said. Accordingly, the adult animals were particularly adapted to long flights over open landscapes. “The wings of the hatchlings were better suited for other forms of flight,” the authors write. “They were probably more dynamic flyers than their parents.”
Another ecological niche
The wing dimensions suggest that the pups were more agile, could take off the ground faster, and could slow down or suddenly change direction during flight. This enabled them to escape predators faster, hunt more nimble prey, and move safely between thick vegetation. Unlike their parents, who preferred open landscapes, the young may have been adapted to life in forests. “In the course of maturation, the flight speed, maneuverability and take-off angle have changed,” write Naish and his colleagues. “Based on these results, we propose that pterosaurs occupied different ecological niches as they grew up.”
Source: Darren Naish (University of Southampton, UK) et al., Scientific Reports, doi: 10.1038 / s41598-021-92499-z