Scientists Discover One of the Most Complete Dinosaur Embryos Ever Found—It Was Inside a 6.7-Inch Egg

A mind-blowing find has turned up in southern China—a fossilized dinosaur egg that turned out to house one of the most complete dinosaur embryos ever discovered. This rare specimen, affectionately dubbed Baby Yingliang, opens a new window into the link between dinosaurs and modern birds (think of it as a key piece of the evolutionary puzzle).

Digging up baby Yingliang

The fossil egg, which measures 6.7 inches long, was found at the Yingliang Stone Natural History Museum in Nan’an, Fujian Province. This egg, estimated to be between 66 and 72 million years old, had been tucked away in a museum warehouse for more than a decade before anyone caught on to its potential. It was originally part of a donation to the museum back in 2000 and probably came from construction work in the Shahe Industrial Park area of Ganzhou City, Jiangxi Province. It wasn’t until 2015 that museum staff noticed its odd features and recognized its significance.

Inside the egg, the embryo has been identified as an oviraptorosaur—a group of feathered theropods that are closely linked to birds. Baby Yingliang, which is about 10.6 inches long, shows an amazing level of bone articulation rarely seen in fossilized dinosaur embryos. Its curled-up, “tucking” position is very similar to that seen in bird embryos right before hatching (this behavior, managed by the central nervous system, is key to ensuring a safe exit from the egg).

What the science says

This is the first time scientists have seen a tucking posture like this in a non-avian dinosaur embryo, which might mean that this behavior started with theropod dinosaurs before birds even evolved. Many modern birds that don’t manage to get into that cozy curled position have a harder time surviving the hatching process, pointing to some deep evolutionary roots.

A study published in iScience in 2021 by Chinese paleontologist Xing Lida and his team described Baby Yingliang’s pose as strikingly similar to that of late-stage modern bird embryos. Paleontologist Waisum Ma from the University of Birmingham noted how rare and exciting it is to find intact dinosaur embryos: “It is very rare to find dinosaur embryos, especially ones that are intact.” Steve Brusatte from the University of Edinburgh added, “This little prenatal dinosaur looks just like a baby bird curled in its egg,” a reminder that many features in today’s birds first started out in their dinosaur ancestors.

Keeping it preserved and looking ahead

Baby Yingliang’s excellent state of preservation is likely thanks to it being quickly buried by sediment—maybe sand or mud—which shielded it from the elements over millions of years. The location where it was found has also given up several other oviraptorid fossils, underlining how important this spot is for understanding the biodiversity in East Asia during the Late Cretaceous.

Although Baby Yingliang stands as the most complete and informative oviraptorid embryo studied so far, scientists are quick to point out that one specimen isn’t enough to paint the whole picture of behavior in all theropods or even just oviraptorosaurs. More finds like this will definitely help round out our understanding.

For now, the specimen remains at the Yingliang Stone Natural History Museum, where researchers continue to examine it and explore what it reveals about the ancient ties between dinosaurs and birds. Each bit of new information brings us a little closer to untangling the fascinating history of life on Earth.