"It is one of the best dinosaur embryos ever found in history," said a researcher about an exquisitely preserved dinosaur embryo of at least 66 million years ago.
Scientists on Tuesday announced the discovery of an exquisitely preserved dinosaur embryo from at least 66 million years ago that was preparing to hatch from its egg like a chicken.
The fossil was discovered in Ganzhou in southern China and belonged to a toothless theropod dinosaur, or oviraptorosaur, which the researchers dubbed "Baby Yingliang".
"This is one of the best dinosaur embryos ever found in history," researcher Phion Waisam Ma of the University of Birmingham, who co-authored a paper in the journal iScience, told AFP.
Ma and his colleagues found that baby Yingliang's head lay beneath its body, with legs and back folded on either side—a posture not previously seen in dinosaurs, but similar to that of modern birds.
In birds, the behavior is controlled by the central nervous system and is called "tucking". Chicks preparing for hatching tuck their heads under their right wing to stabilize the head while cracking the shell with their beak.
Embryos that fail to hatch have a higher chance of death from unsuccessful hatching.
"This indicates that this type of behavior in modern birds first evolved and originated among their dinosaur ancestors," Ma said.
An alternative to tucking might be something closer to what is seen in modern crocodiles, which instead consists of a sitting posture, with the head bent over the chest until hatching.
Oviraptorosaurs, meaning "egg thief lizard," were feathered dinosaurs that lived in what is now Asia and North America during the Late Cretaceous period.
They had variable beak size and diet, and ranged in size from the lower end of modern turkeys to the massive gigantoraptors, which were eight meters (26 ft) long.
Baby Yingliang is about 27 cm (10.6 in) long from head to tail, and is inside a 17 cm long egg in the Yingliang Stone Nature History Museum.
Researchers believe the creature is 72 to 66 million years old, and was probably protected by a sudden mudslide that buried the egg, protecting it from scavengers for eons.
It would have been two to three meters tall if it had lived to be an adult, and would probably have been feeding on plants.
The specimen was one of several egg fossils that had been forgotten in storage for decades.
The research team suspected that they might contain unborn dinosaurs, and removed part of baby Yingliang's egg shell to uncover the embryo hidden inside.
"This dinosaur embryo inside an egg is one of the most beautiful fossils ever found," Professor Steve Brussett from the University of Edinburgh said in a statement.
"This small prenatal dinosaur looked like a baby bird curled up in its egg, which is yet further evidence that many of the characteristics of today's birds first evolved in their dinosaur ancestors."
The team hopes to use advanced scanning techniques to study Baby Yingliang in more detail to image her entire skeleton, including her skull bones, as part of the body is still covered with rock.