Rare ancient baby turtle identified inside a fossil egg – .

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Rare ancient baby turtle identified inside a fossil egg – .


A fossil egg found by a Chinese farmer turned out to have a rare surprise inside: a baby turtle almost ready to hatch. And it allowed scientists to make a unique and important connection, reports a new study.
“It is in fact the first time that [fossil] turtle eggs or a nest could really be attributed to a particular turtle, ”said Darla Zelenitsky, study co-author and associate professor of paleontology at the University of Calgary.

The egg belonged to a nanhsiungchelyid turtle, an ancient and huge land creature that lived in Asia and North America and was related to modern softshells, according to the study. published Wednesday in the journal Proceedings of the Royal Society B.

The turtle lived among dinosaurs – such as long-necked, herbivorous sauropods, duck-billed hadrosaurs, and large meat-eaters, similar to tyrannosaurs – during the Cretaceous Period. He died with them.

“It was a giant tortoise back then,” Zelenitsky said.

She estimates that the female who laid the egg was over 1.6 meters long – about as long as an average female is taller and longer than a giant Galapagos tortoise, although she has a carapace flatter and less convex.

University of Calgary paleontologist Darla Zelenitsky holds a 3D printed model of the fossil turtle egg, which was roughly the size and shape of a tennis ball. (Darla Zelenitsky)

Like the Galapagos tortoise, it lived entirely on land. The Nanhsiungchelyids lived in arid desert environments, but the egg was found near the banks of an ancient river.

“During the rainy season, these river systems may have overflowed and buried the eggs that were in the floodplain, potentially preserving them as fossils,” Zelenitsky said.

The region of Henan in China where it was found is also known for its fossil dinosaur eggs, she said.

The fossil egg was found in 2018 by a farmer in China’s Henan Province. (Yuzheng Ke)

The estimated size of the embryo’s mother is based on the known relationship between a turtle’s body size and its eggs. The fossil is about the size and shape of a tennis ball – perfectly spherical – with a shell as thick as that of a much larger ostrich egg.

“I was like, ‘How did that little turtle come out of that egg, when it’s so thick?’ Zelenitsky remembers. “They had to do a lot of flexes and extensions… to get out. ”

The embryo was extremely well preserved, allowing researchers to X-ray it with a CT scanner and reconstruct its skeleton in 3D. They concluded that it was a nanhsiungchelyid after comparing it to other ancient and modern turtles.

Egg helps identify nests

By identifying this egg, which was found on its own, the researchers were also able to identify whole nests of identical turtle eggs found elsewhere. He showed that nanhsiungchelyidae normally lay 15 to 30 eggs at a time.

This artist’s rendering shows baby nanhsiungchelyid turtles hatched from their eggs. The fossil with the embryo allowed researchers to identify identical eggs in other nests, showing that they were usually laid in clutches of 15 to 30. (Masato Hattori)

The farmer who initially found the egg in 2018 donated it to a museum.

Lead author of the study, Yuzheng Ke, a graduate student at the Chinese University of Geosciences in Wuhan, contacted Zelenitsky and asked her to participate as she had previously researched dinosaur eggs and even a pregnant turtle. .

Zelenitsky said she jumped at the chance: “I was excited about this all the time. “

The study was funded by the National Natural Sciences Foundation of China and the Natural Sciences and Engineering Research Council of Canada.

Daniel Lawver, a researcher at Stony Brook University School of Medicine in New York who was not involved in the study, conducted similar, not yet published, research on a different turtle egg and embryo.

He was pleasantly surprised by the study, he said, because a turtle with an identifiable embryo inside is a “very, very rare” find and this one is a “really cool specimen.”

This is because most turtles have thin eggshells made up of a mineral called aragonite which is unstable on the Earth’s surface. During fossilization, it is converted into another mineral that makes them difficult to identify, Lawver said. And often, they are fossilized before the embryo has developed, resulting in a rock-filled fossil eggshell.

This is the fossil of an adult nanhsiungchelyid turtle from Alberta. The adult nanhsiungchelyid were very tall. Whoever laid the egg was estimated to be 1.6 meters long. (Musée royal Tyrell)

Jordan Mallon, a paleontologist at the Canadian Museum of Nature who has studied nanhsiungchelyid fossils from North America, including Alberta, agrees with the identification of the embryo. He was also not involved in this research.

The thick, water-retaining eggshells add to the evidence that the turtles lived entirely on land, he said, something that has been debated.

The techniques used in the study could then be used to examine older turtle embryos and uncover long-standing puzzles about turtle evolution, such as the evolution of their shell, Mallon said.

“I think the authors of this article are sort of leading the way. “

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