Rio de Janeiro: The largest collection of fossilized pterosaur eggs ever found has shown that pterosaurs, the airborne cousins of dinosaurs, could not fly immediately and needed their parents' attention, researchers reported Thursday.
Pterosaurs were reptiles, and the first creatures-after insects-to evolve motorized flight, which means that they flapped their wings to stay upright instead of just jumping and sliding.
First it was known that they existed 225 million years ago, they became extinct along with the dinosaurs about 65 million years ago.
Until now, scientists had found some pterosaur eggs with remains inside, including three in Argentina and five in China.
But the latest report in the peer-reviewed American journal Science is based on the largest collection to date: 215 fossilized eggs found in a 3m long sandstone block in the city of Hami , northwest of China Uygur Autonomous Region.
"Given that these are extremely fragile fossils, we were surprised to find so many in the same place," Brazilian paleontologist Alexander Kellner told AFP.
"Because of this discovery, we can talk about the behavior of these animals for the first time."
Sixteen of the eggs contained remains fossilized from a species of pterosaur known as Hamipterus tianshanensis.
As adults, these creatures would have been about 1m tall, with a wingspan of 3m.
None of the eggs contained a complete set of pterosaur bones, probably because pieces were lost over the years due to storms and floods.
But scientists found partial wing and skull bones, along with a full lower jaw, that complete aspects of the life cycle of pterosaurs that have so far been misunderstood.
Using three-dimensional computed tomography scans, they discovered intact, well-developed bones that suggest that the creatures "benefited from the functional hind legs shortly after hatching," the report said.
But his chest muscles were weak.
"This shows that when pterosaurs were born, they could walk but not fly," said Kellner
"They needed their parents, this is one of the biggest discoveries we've made."
adult Pterosaur bones were also scattered around the site, a signal that they returned to the same nesting sites over time, much like the modern sea turtles.
The mbadive amount of eggs and bones points to heavy storms hitting the site, immersing the eggs in a lake where they floated briefly before sinking and burying themselves with adult skeletons.
The researchers also noted that the cracked exterior of the eggs resembled the fragile softness of the lizard eggs.
"All are deformed to some extent, which indicates their flexible nature," the study said.
One of the young pterosaurs was estimated to be "at least two years old and still growing at the time of his death, which supports the growing body of evidence that pterosaurs had long incubation periods."
A companion article in the journal Science written by D. Charles Deeming of the University of Lincoln, described the study as "remarkable by the number of ovules in badociation with adult and juvenile pterosaurs that reports on" .
However, many questions remain, even if the size of each clutch was really two, as previous studies suggest, how the pterosaurs hid their eggs, either under vegetation or sand or dirt, and why so many eggs they appear dehydrated.
"Fortunately, additional findings from equally spectacular fossils will help us answer such questions," he wrote.