Scientists working at a site in northern China have found 215 rare fossil eggs of pterosaurs – flying reptiles that lived alongside the dinosaurs.
The fossilised eggs were discovered at a site in a remote desert region in Xinjiang in northwest China.
It is the largest collection of the reptiles' eggs yet found and will offer a glimpse into how the pterosaurs lived, according to researchers.
The findings were published in the journal Science on Friday by Chinese and Brazilian based researchers.
Wang Xiaolin, a scientist at the Institute of Vertebrate Palaeontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing, has spent over 10 years with his team investigating the area in Hami in Xinjiang.
He told the Chinese news website Thepaper.cn that the area – which he has previously called the Garden of Eden for pterosaurs – is rich in finds.
"[You could] discover one pterosaur in an area of one square metre," Wang was quoted as saying.
The eggs date to the Lower Cretaceous period, between 145 million and 100 million years ago.
Pterosaurs are the earliest vertebrates known to have evolved powered flight and the reptiles flew above lakes and shallow seas.
Sixteen of the eggs found in Xinjiang have a fossilised embryo inside, the most complete with a partial wing and cranial bones including a complete lower jaw.
The researchers believe that rather than living alone, pterosaurs lived in groups. This would explain why so many fossil eggs and pterosaur remains were discovered in the same place.
CT scans of one of the eggs also showed the early teeth of embryonic pterosaurs developed quite late, suggesting their young would still needed feeding and caring for by their parents after birth.
The lack of muscles to support wing bones supported the idea that baby pterosaurs walked on the ground and probably were unable to fly at an early age.
More from the South China Morning Post :
Dinosaur egg fossil find cracks open China's prehistoric past
Mysterious Planet X will apparently destroy Earth Sunday, and this Nasa scientist says we should all just chill
North Korean coal piles up as sanctions take their toll and exports to China grind to a halt