In many modern bird species, a parent can often be seen returning to the nest after a successful hunt to feed its young, which are not yet big enough to feed themselves. Such a scene probably did not apply to pterosaurs. Darren Naish of the University of Southampton, UK, and colleagues showed that these flying reptiles, which became extinct 66 million years ago, were physically capable of flapping flight almost from birth.
Pterosaurs form an extensive group of winged reptiles, the smallest of which do not exceed the size of a sparrow, and the largest, such as Quetzalcoatl, are the largest known flying species ever to have lived on Earth, with a wingspan of over 10 meters. But the question of at what age young pterosaurs learned to fly remains open. Their fossils show that wings were already well formed at birth, but examples of hatchlings already capable of flight long before their growth is complete are very rare among modern animals. Therefore, Darren Neish and colleagues proposed a quantitative approach to determine whether young pterosaurs were morphologically capable of flight.
Their analysis is based on two parameters: the ability to glide and the force required to flap the wings (or shoulder strength). The first depends on the load on the wing, the ratio of the mass of the bird to the area of its wings. Using the fossils of very young pterosaurs and their wingspan, the researchers estimated the load on their wings and compared it to that of modern non-avian species that can glide, such as flying squirrels and snakes. Chrysopelia paradisiac or lizard Draco Melanopogon. The wing loading of young pterosaurs was far more advantageous than those of these species, and allowed them to soar for much longer, potentially hundreds of meters. Thus, even at an early age, pterosaurs were physically able to fly longer and were probably not content to bounce themselves from tree to tree during gliding.
Moreover, they had strong shoulder strength, necessary for both takeoff and wing beats. The researchers assessed it by the strength of the fossil’s humerus (the most stressed bone in wing beats) and its proportion compared to the rest of the skeleton. Even if they caution that this ability was highly heterogeneous across pterosaur species, Darren Neish and colleagues suggest that the morphological abilities of the young were even more adapted to flight than those of their parents!
For researchers, morphological differences between juvenile and adult pterosaurs may even imply hunting habits and activities in different ecosystems depending on age. With a small wingspan, a good ability to take off, and the ability to change pace or direction, it would be easier for young pterosaurs to live in the forest. Once growth was complete, their larger, agile elders were more suited to long-duration flights in open space, possibly a marine environment. The largest species of the genus, with a wingspan comparable to that of a small aircraft, would even be able to cross the oceans.