The little pterosaurs may have been able to fly straight out of their shells, although the flight of those ancient reptiles may have seemed a little different than that of adults. A new analysis of the fossilized bones of the wings of embryonic pterosaurs, newborns and adults suggests the cubs were strong and agile flyers from the start, the researchers report July 22 on Scientific Reports.
Pterosaurs were a diverse group of ancient flying reptiles that lived alongside dinosaurs from the Triassic to the Cretaceous, 228 to 66 million years ago. The group includes Quetzalcoatlus northropi, the largest creature known to take volor, and Kunpengopterus antipollicatus (aka “Monkeydactyl”) which had opposable thumbs that allowed it to climb trees.
Scientists know relatively little about the early life history of pterosaurs, including whether their young could actively flap their wings or just glide, which could mean they remained in parental care until they were ready for flight.
Pterosaurs able to fly agile and for long distances
But recent revelations point increasingly towards early independence, for reptiles, such as the discovery of flight membranes on the wings of an embryonic pterosaur and the discovery of a tiny juvenile Pteranodon that was capable of long-distance flight. long before they grow to adult size.
“Pterosaur cubs almost certainly didn’t glide,” says Kevin Padian, a paleontologist at the University of California, Berkeley, who was not part of the new study. The three keys to flight, he says, are strong bones, enough muscle mass to stay long in the air, and sturdy keratin fibers in the skin of the wings, analogous to bird feathers. “We know little about the last two.”
So the researchers turned to bones. Darren Naish, a paleontologist at the University of Southampton in England, and his colleagues compared measurements of the fossilized embryo and wings of the young with those of adults of two species. Pterodaustro guinazui and Sinopterus dongi.
The researchers analyzed the wingspan, the strength of the wing bones and the load the wings could carry. Specifically, they focused on one bone in one wing, the humerus. That bone is found on the limbs that pterosaurs use to launch themselves into flight and offers key information about a pterosaur’s ability to get up off the ground.
The team found that the humerus bones of the young they were surprisingly stronger than those of many adults. Hatchlings also had shorter and wider wings than adults, suggesting that they might be able to nimbly change direction and speed, if not fly long distances.
The agile flight may have helped the young not only escape predators, but also chase difficult prey such as insects, all while navigating the dense vegetation, the team suggests. Adult pterosaurs, less able to maneuver due to their size, may therefore have moved on to more open habitats.
Among modern birds, the ability to fly immediately after hatching is almost unknown. with the notable exception of the maleo, a strange chicken-like bird that lives only on the Indonesian island of Sulawesi. The maleo’s ability to take flight helps him avoid being captured by the island’s various predators, from monitor lizards to pythons.
However, it’s not unusual in most of the animal world for young people to be able to fend for themselves, Padian says. “Earliness is the rule, not the exception, in vertebrates”, He says. Only animals with extensive parental care, such as songbirds or primates, can afford to be helpless for an extended period of time.