Scientists in China have discovered a 121 million-year-old fossil containing an embryo of a flying reptile that lived alongside the dinosaurs.
It is the only known fossil of an embryo of a pterosaur, a winged lizard that was capable of powered flight.
“Dinosaur embryos have been discovered all over the world, but so far no pterosaur embryos have been reported,” Xiaolin Wang and Zhonghe Zhou, of the Chinese Academy of Sciences in Beijing, reported in Thursday's issue of the journal Nature.
The embryo is preserved in an almost complete egg and was found in the sediment of a lake in Liaoning in northeastern China that is known for its fossil riches.
Parts of its skull and skeleton are preserved, and the lower jaw shows two slender and slightly curved teeth, according to the scientists.
It is bigger than fossils of hatched pterosaurs, which suggests it probably would have hatched soon.
“The Liaoning embryo has a wingspan of 27 centimeters (10.6 inches), indicating that the embryo would have grown up into a medium-to-large pterosaur,” the scientists added.
The earliest pterosaurs, the first known flying vertebrates, lived about 230 million years ago. They died out about 65 million years ago.