WASHINGTON, 1 December (BelTA - Xinhua) - Over 200 three-dimensionally preserved eggs of pterosaurs have been unearthed in China, providing new insight into the life history of the rulers of the skies in the age of dinosaurs, scientists said Thursday.
Pterosaurs were the first vertebrates to evolve powered flight and they dominated the skies during the age of dinosaurs, which spans from about 252 million years ago to about 66 million years ago.
To date, only 11 pterosaur eggs have been found, three of which have fossilized embryos inside.
Five of the eggs were also found in the Turpan-Hami Basin, where a huge lake once existed in the Cretaceous period.
Now, this sparse sample size was dramatically increased upon the discovery of the 215 Hamipterus eggs that are estimated to be 120 million years old based on the geological information.
The large quantities of eggs, together with bones and other specimens, indicated the now extinct animals participated in colonial nesting behavior, said study researcher Xiaolin Wang, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing.
More importantly, 16 of these eggs contain embryonic remains of varying intactness, representing the first time three-dimensional pterosaur embryos have been discovered.
The most complete embryo contains a partial wing and cranial bones, including a complete lower jaw, said the study.
"From our discovery, we conclude that the newborns of pterosaurs, at least Hamipterus, were likely to walk on the ground, but were not able to fly in the sky because the femur in the embryo is well developed, but the forelimbs are not well developed," Wang said.
"Hence, this pterosaur is a precocious creature, but not so precocious as previously thought, and probably needed some parental care," he said.
Based on growth marks, the team also 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.
