About 90 million years ago, giant turtle In what is now central China, he laid a group of eggs the size of tennis balls with very thick eggshells. Never a single egg hatched, and it remained undisturbed for tens of millions of years, preserving the delicate bones of the embryonic turtle inside.
In 2018, he found an egg farm and donated it to the university. Now, a new analysis of this rare egg and embryo marks the first time scientists have been able to identify the species dinosaur– Age of turtle embryos.
This specimen also explains the reason for the existence of its own species, the tortoise Yuchelys nanyangensisExtinct 66 million years ago at the end lime periodWhen an asteroid hits, it kills the dinosaurs a land. The thicker egg shells allowed water to seep in, the researchers said, so the clutches of the eggs were likely buried in deep underground nests in moist soil to prevent them from drying out in the arid environments of central China during the late Cretaceous period.
While this turtle’s unique wildlife lifestyle, thick eggs, and underground nesting strategy may have benefited them during the Cretaceous, it is possible that this particular turtle was unable to adapt to “colder climate and ecological changes following the end-time mass extinction.” . the Chalk.” Study co-author Darla Zelenitsky, professor of paleobiology at the University of Calgary in Canada, told Live Science.
Related: Image: These animals are giants
Discovery of the egg
Zelenitsky said the farmer found the eggs in Henan Province, an area known for the thousands of dinosaur eggs people have found there over the past 30 years. But compared to dinosaur eggs, turtle eggs — especially those with preserved embryos — rarely degrade because they are so small and fragile, he said.
NS Y. Nanyangensis However, the egg has survived because it is an egg tank.
Measuring 2.1 x 2.3 inches (5.4 x 5.9 cm), the roughly round egg is slightly smaller than a tennis ball. It is larger than the eggs of most live turtles, and slightly smaller than turtle eggs Galapagos Zelenitsky berkata:
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The eggshell thickness of 0.07 inches (1.8 mm) is also important. By comparison, it is four times thicker than the shell of a Galapagos tortoise, and six times thicker than the shell of a chicken egg, which is average thick. 0.01 inch (0.3mm). Larger eggs tend to be thicker, such as an ostrich egg shell that is 0.08 inches (2 mm) thick, but “these eggs are much smaller than ostrich eggs,” which average around 6 inches, inches He is 15 cm tall, says Zelenitsky.
The researchers found that an equation that uses egg size to predict the length of a turtle’s carapace, or the top of a turtle’s shell, reveals that this thick egg was laid by a 5.3-foot (1.6 m) long turtle shell. . These measurements do not include the length of the neck or head, so the mother tortoise is easy over several human lengths.
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abandoned eggs
The researchers used micro-CT scan To create a virtual 3D image of an egg and its embryo. By comparing these images with living, distantly related turtle species, the researchers found that the fetus was about 85% more developed.
Zelenitsky noted that part of the eggshell broke, so he “may have tried to hatch” but failed. Apparently, it wasn’t the only turtle embryo that didn’t work out; Two of the thick-shelled egg clutches previously excavated from Henan Province date back to the Cretaceous period – one containing 30 eggs and the other containing 15 – also likely belong to this now extinct family of turtles, known as Nanhsiungchelyid, the researchers said. .
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Turtles in this family — relatives of today’s river turtles — were very flat and evolved to live entirely on land, which is unique during that period, Zelenitsky said.
Walter Joyce, a professor of paleontology at the University of Fribourg in Switzerland, who was not involved in the study, said the newly discovered egg research was primarily for virtual 3D analysis of embryos, which helped lead to species diagnosis. Additionally, the study provides evidence that Nanhsiungchelyid tortoises “adapted to live in harsh terrestrial environments, but lay their large, thick-shelled eggs in closed nests in moist soil,” Joyce told Live Science in an email.
The study will be published online Wednesday (August 18) in the journal Proceedings of the Royal Society B: Biological Sciences.
Originally published in Live Science.
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