The uncommon fossil embryo of an oviraptor is revealing a shocking connection between the hatching conduct of dinosaurs and fashionable birds, based on new analysis.

A clutch of unhatched dinosaur eggs, although not formally recognized as such, was found in China’s Jiangxi province in 2000. The fossils, pulled from the Late Cretaceous Hekou Formation of southern China, promptly ended up in storage and have been largely forgotten. It was solely throughout building of the Yingliang Stone Nature History Museum within the 2010s that museum employees, after sorting by means of the storage, rediscovered the specimen, dated to between 66 million and 72 million years previous.

These fossils have been subsequently recognized as dinosaur eggs, as Lida Xing, the primary creator of a brand new iScience paper describing the invention, defined in a University of Birmingham press launch. “Fossil preparation was conducted and eventually unveiled the embryo hidden inside the egg,” mentioned Xing, a paleontologist at China University of Geosciences.

The fossilized embryo, dubbed “Baby Yingliang,” was recognized as an oviraptor, a various group of feathered theropod dinosaurs carefully associated to fashionable birds. The discovery of a fossilized embryo is a uncommon prevalence, however Baby Yingliang is additional particular on account of its bodily posture contained in the 6.7-inch-long (17-centimeter) egg.

“This dinosaur embryo inside its egg is one of the most beautiful fossils I have ever seen,” Steve Brusatte, a co-author of the examine and a paleontologist on the University of Edinburgh, mentioned within the press launch. “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.”

Indeed, evaluation of the embryo confirmed it to be in a decent fetal place, with its head tucked into the physique and backbone nestled alongside the curvature of the egg shell. Uncurled, it will be 10.6 inches lengthy (27 cm). Scientists discuss with this as “tucking” conduct, which is noticed in fashionable birds.

In an e-mail, Fion Waisum Ma, a paleobiology PhD scholar on the University of Birmingham and a co-author of the brand new examine, mentioned this posture “is similar to a close-to-hatching modern bird embryo” and “similar to a 17-day-old chicken embryo,” which are likely to hatch on day 21.

Tucking is triggered by the growing embryo’s central nervous system and that is deemed essential for hatching success. The last place previous to hatching “has been suggested to help stabilize and direct the head, when the bird is cracking the eggshell using its beak,” Ma defined. “Failure to achieve this final position would lower the chance of successful hatching, and the bird would die inside the egg.”

This fossil, due to this fact, suggests a possible evolutionary hyperlink between the hatching conduct of dinosaurs, particularly non-avian dinosaurs (as evidenced on this case), and fashionable birds (often known as avian dinosaurs—and sure, all birds are dinosaurs).

“Tucking was previously considered unique to birds, but our findings suggest theropod dinosaurs like [oviraptors] could have had this behaviour as well,” mentioned Ma. “This indicates tucking behaviour in modern birds could have first evolved among their dinosaurian ancestors.”

It’s an intriguing discovering, however Shundong Bi, a paleontologist at Indiana University of Pennsylvania who wasn’t concerned within the new examine, isn’t satisfied. “I am skeptical about the tucking behavior as it is primarily based on a single specimen,” Bi defined in an e-mail.

The air cell, or air pocket, inside an egg rapidly expands within the days previous to hatching, and it’s the place a growing embryo takes its first breath. The authors of the brand new examine interpreted the house between the embryo’s backbone and the blunt pole of the egg (the bigger finish of the egg) because the air cell noticed in fashionable fowl eggs, however Bi mentioned it’s not clear that’s what the fossil reveals.

Recognizing the small pattern dimension of 1, the crew is hoping that comparable fossils will finally come to gentle. Additional proof would do a lot to strengthen this idea, that tucking originated or was at the very least current amongst non-avian theropods. Looking forward to future analysis, the crew want to examine the fossil with totally different imaging methods “to look inside the specimen and study its anatomy in more detail,” mentioned Ma. That’s excellent news, as Baby Yingliang might have extra tales to inform.

More: Extraordinary Fossil Captures Nesting Oviraptor Dinosaur Alongside Unhatched Offspring.