A well-preserved dinosaur embryo has been discovered inside a fossilized egg in southern China, precisely in Ganzhou, Jiangxi Province, and researchers estimate that it goes back to at least 66 million years and was probably preserved by a sudden mudslide that buried the egg.

Researcher Dr. Fion Waisum Ma commented on the discovery by saying it is "the best dinosaur embryo ever found in history.” 

According to a news release, researchers at Yingliang Group - a company which services include mine exploration, mining and stone trading - suspected it contained egg fossils and stored it for 10 years. When construction began on Yingliang Stone Natural History Museum, boxes of unearthed fossils were searched through. 

"Museum staff identified them as dinosaur eggs and saw some bones on the broken cross section of one of the eggs," Lida Xing of China University of Geosciences, Beijing, disclosed. The embryo was found hidden within; it was named "Baby Yingliang," after the name of the Chinese museum which keeps the fossil.

"It is an amazing specimen ... I have been working on dinosaur eggs for 25 years and have yet to see anything like it," said Darla Zelenitsky, an associate professor in the geoscience department at Canada’s University of Calgary and a coauthor of a related research published in the iScience journal on Tuesday.

Baby Yingliang measures 10.6in (27cm) long from head to tail and rests inside a 6.7 inch-long egg.

Waisum Ma, the study’s lead author and a researcher at the University of Birmingham in UK stated "We were surprised to see this embryo beautifully preserved inside a dinosaur egg, lying in a bird-like posture."

Such conduct before the hatching process is not the sole conduct that modern birds took from their dinosaur ancestors. The same type of dinosaurs is also known to have sat on top of their eggs to incubate them in a way akin to birds, Zelenitsky explained.

"This indicates that such behavior in modern birds first evolved and originated among their dinosaur ancestors," Dr. Ma told the AFP news agency.

Bird-like?

The embryo is that of the bird-like oviraptorosaurs, part of the theropod, which means "beast foot," but theropod feet usually resembled those of birds. Birds come from one lineage of small theropods. 

While studying the baby dinosaur, researchers found it took on a distinctive tucking position before hatching, which had been known as exceptional to birds.

While fossilized dinosaur eggs have been found during the last centenary, discovering a well-preserved embryo is infrequent, the researchers said in a news release. 

The embryo's position was not seen before in non-avian dinosaurs, which is "especially notable because it's reminiscent of a late-stage modern bird embryo," according to the researchers, who will continue their thorough study of the rare specimen and attempt to picture its internal anatomy as some of its body parts are still covered in rocks.

It is worth noting that their findings can be also used in further studies of fossil embryos.