Baby pterosaurs could probably fly within hours or even minutes of hatching. Their wings were already ideally suited for powered flight, according to a new analysis of fossil wing bones.
“We’re not the first people to say this,” says Darren Naish at the University of Southampton in the UK. “The main strength of our study is it’s combining several different lines of evidence.”
Pterosaurs were flying reptiles related to the dinosaurs, and which lived alongside them. They include Quetzalcoatlus which, with its 10-metre wingspan, was the largest flying animal known to have existed.
But even the largest pterosaurs didn’t start out that way. They hatched from eggs, at which point even the largest species were no bigger than a modern gull.
Palaeontologists have argued for years over how soon young pterosaurs could fly. Some have argued that they were incapable of flight when they first hatched, like most modern birds, and only took to the air after many weeks or even months. But others have put forward evidence that they could fly almost immediately – like some Australian megapode birds today.
Naish and his colleagues examined the fossilised bones of three young Pterodaustro guinazui and one young Sinopterus dongi – two very distantly related pterosaur species. They examined the strengths of the baby pterosaurs’ wing bones, as well as their wingspans and other measurements. They found the baby pterosaurs had ideal wings for powered, flapping flight.
This contradicts the claim that baby pterosaurs were flightless. “I would say this demolishes that,” says Naish. It also doesn’t support a “compromise” hypothesis that baby pterosaurs could glide without active flapping. “We also refute that,” says Naish.
Naish suspects instead that baby pterosaurs of all or most species could stand up, walk and fly very early in life. “My gut feeling is minutes, but certainly within hours of hatching,” says Naish.
What’s more, the baby pterosaurs seem to have been adapted to a different style of flight compared to the adults. Their short wings were ideal for flying through cluttered environments like forests, whereas the bigger adults needed more open spaces.
For Naish, this implies that they lived in different places and ate different prey – perhaps allowing a single species to dominate multiple environments over the animals’ lifespans, as has been suggested for Tyrannosaurus rex. If that is true, it means the adult pterosaurs can’t have done much parenting. In most pterosaur species, the babies “don’t have anything to do with adults until they become [about] half-sized”, suggests Naish.
Journal reference: Scientific Reports, DOI: 10.1038/s41598-021-92499-z
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