An incredibly rare egg with an embryo still inside was laid by a gigantic turtle during the time of the dinosaurs. Named Yuchelys nanyangensis, the giant terrestrial turtle laid a bunch of eggs in Henan Province, China, about 90 million years ago but one of them never hatched. These eggs were almost the size of a tennis ball with exceptionally thick shells.
The egg was initially discovered back in 2018 by a farmer who then donated it to a university. Since then, there has been extensive analysis on the egg and the experts have now revealed their findings. This is a very significant discovery as it is the first time ever that scientists have identified a dinosaur-aged turtle based on an embryo.
The egg measures 2.1 by 2.3 inches. To put this into better perspective, it is bigger than the majority of eggs laid by today’s turtles except for the Galápagos tortoises that lay eggs slightly larger than the one left behind by the Yuchelys nanyangensis species. The thick shell measures 0.07 inches which is approximately six times thicker than a chicken egg and four times thicker than those of a Galápagos tortoise.
Based on the egg size, the experts were able to estimate how large the turtle was that laid it and they predicted that its carapace (the hard upper shell of a turtle) probably measured about 5.3 feet in length (1.6 meters) – the size of a human standing up. Incredibly, this predicted length doesn’t even include its neck or head.
As for the embryo, a micro-CT scan created a 3D image of it, revealing that it was almost 85% developed. Darla Zelenitsky, who is an associate professor of paleobiology at the University of Calgary in Canada, told Live Science that a portion of the eggshell was broken so “maybe it tried to hatch”. (A picture of the egg can be seen here.)
The Yuchelys nanyangensis species’ family called Nanhsiungchelyid were the extinct relatives of today’s river turtles, but these flat ancestors lived solely on land which was apparently quite rare during the Cretaceous Period. They went extinct about 66 million years ago when the dinosaur-killing asteroid hit Earth. The eggs were probably buried deep beneath the ground in moist soil so that they wouldn’t dry out which would have helped them during the Cretaceous Period; however, when the climate changed due to the asteroid impact, the turtles may have had a difficult time adapting to the cooler “climatic and environmental changes following the end-Cretaceous mass extinction” as explained by Zelenitsky.
The study was published in the journal Proceedings of the Royal Society B: Biological Sciences where it can be read in full.