On Tuesday, scientists announced the discovery of an exquisitely preserved dinosaur embryo from at least 66 million years ago, which was preparing to hatch from its egg in the same way that a chicken does.
The fossil was discovered in Ganzhou, southern China, and belonged to an oviraptorosaur, or toothless theropod dinosaur, which the researchers dubbed “Baby Yingliang.”
“It is one of the best dinosaur embryos ever found in history,” Fion Waisum Ma, a University of Birmingham researcher who co-authored a paper in the journal iScience, told AFP.
Ma and colleagues discovered Baby Yingliang’s head below its body, with feet on either side and back curled — a previously unseen posture in dinosaurs but similar to modern birds.
In birds, the behavior is known as “tucking,” and it is controlled by the central nervous system. Chicks preparing to hatch tuck their heads under their right wing to stabilize the head while cracking the shell with their beak.
Embryos that do not tuck have a greater chance of dying as a result of an unsuccessful hatching.
“This indicates that such behavior in modern birds first evolved and originated among their dinosaur ancestors,” said Ma.
An alternative to tucking could have been something more akin to what is seen in modern crocodiles, which sit with the head bending upon the chest up to hatching.
Oviraptorosaurs, which translates as “egg thief lizards,” were feathered dinosaurs that lived during the Late Cretaceous period in what is now Asia and North America.
They had different beak shapes and diets, and their sizes ranged from modern turkeys to massive Gigantoraptors that were eight meters (26 feet) long.
Baby Yingliang is approximately 27 centimeters (10.6 inch) long from head to tail and is housed in a 17 centimeter-long egg at the Yingliang Stone Nature History Museum.
The creature is thought to be between 72 and 66 million years old and was most likely preserved by a sudden mudslide that buried the egg, protecting it from scavengers for eons.
If it had lived to adulthood, it would have grown to be two to three meters long and would have eaten plants.
The egg fossil was one of several that had been forgotten in storage for decades.
The researchers suspected they might contain unborn dinosaurs, so they scraped away a portion of Baby Yingliang’s egg shell to reveal the embryo hidden within.
“This dinosaur embryo inside its egg is one of the most beautiful fossils I have ever seen,” Professor Steve Brusatte of the University of Edinburgh, who was a member of the research team, said in a statement.
“This little prenatal dinosaur looks just like a baby bird curled in its egg, which is yet more evidence that many features characteristic of today’s birds first evolved in their dinosaur ancestors,” Brusatte further stated.
Because part of Baby Yingliang’s body is still covered by rock, the team hopes to study it in greater depth using advanced scanning techniques to image its full skeleton, including its skull bones.