They were known to rule the skies in the Jurassic and Cretaceous periods, but it seems that pterosaurs had a slow start in life.
A new study has revealed that the giant reptiles had a two year incubation and couldn’t fly when they hatched.
The findings suggest that new pterosaurs were ‘less precocious than previously assumed.’
The discovery of 215 eggs of the pterosaurs species Hamipterus tianshanensis in China is providing new insights into the development and nesting habits of pterosaurs
Pterosaurs were the first animals after insects to evolve powered flight and were highly successful evolving from relatively small flying reptiles into dozens of species over 150 million years.
But like the T-Rex they died out 66 million years ago with few fossil remains.
Until now, only three eggs with a well-preserved 3D structure and embryo inside had been found and analysed from Argentina and five from China.
But the discovery of 215 eggs of the pterosaurs species Hamipterus tianshanensis in China is providing new insights into the development and nesting habits of pterosaurs.
Xiaolin Wang, from the Chinese Academy of Sciences in Beijing, who led the study, said: ‘Fossil eggs and embryos that provide unique information about the reproduction and early growth of vertebrates are exceedingly rare, particularly for pterosaurs.
‘Here we report on hundreds of three-dimensional (3D) eggs of the species Hamipterus tianshanensis from a Lower Cretaceous site in China, 16 of which contain embryonic remains.’
The study used computed tomography scanning to peer inside the eggs.
The most complete embryo contained a partial wing and cranial bones, including a complete lower jaw.
The samples of thigh bones that remained intact were well-developed, suggesting that the species benefited from functional hind legs shortly after hatching.
But the structure supporting the pectoral muscle appeared to be underdeveloped during the embryonic stage, suggesting that newborns were not able to fly.
This suggested the newborns likely needed some parental care.
Neither birds nor bats, pterosaurs were reptiles who ruled the skies in the Jurassic and Cretaceous periods (artist’s impression pictured)
Based on growth marks, the team estimated one of the individuals to be at least two years old and still growing at the time of its death, supporting the growing body of evidence that pterosaurs had long incubation periods.
And the fact a single collection of embryos exhibited a range of developmental stages hints that pterosaurs participated in colonial nesting behaviour.
Dr Charles Deeming, of the University of Lincoln, who was not involved in the study, said: ‘The relatively low incubation temperatures associated with environmental sources of heat would have meant a long incubation period, as is now suggested for dinosaurs, and hatching of a relatively mature and mobile offspring, as seen in modern reptiles.’
He noted the while the study suggested that the hatchlings were unable to feed themselves, this may not be the case.
He added: ‘An alternative perspective is that the embryos were much younger than estimated and not close to hatching and that the lack of growth of teeth is therefore unsurprising; in crocodilians, teeth only arise in the later stages of development.’