A mysterious Antarctic fossil is a massive egg

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The fossil that has baffled scientists for a long time is in fact the largest soft-shelled egg ever found, laid around 68 million years ago, probably by a type of sea snake or extinct lizard.

TOKYO: Scientists dubbed it “The Thing” – a mysterious fossil about the size of a soccer ball discovered in Antarctica that was in a Chilean museum while waiting for someone who could understand what it was.

Now, analysis has revealed that the mysterious fossil was a soft-shelled egg, the largest ever found, laid about 68 million years ago, possibly by a type of sea snake or extinct lizard.

The revelation ends nearly a decade of speculation and could change thinking about the lives of sea creatures at that time, said Lucas Legendre, lead author of an article detailing the findings, published Wednesday in the journal Nature.

“It is very rare to find such a well-preserved soft-shell fossil egg,” Legendre, a post-doctoral researcher at the University of Texas at Austin, told AFP.

“This new egg is by far the largest soft-shelled egg ever discovered. We did not know that these eggs could reach such a huge size, and since we assume that it was laid by a giant marine reptile, it could also be a unique insight into the reproductive strategy of these animals, “he said. -he declares.

The fossil was discovered in 2011 by a group of Chilean scientists working in Antarctica. It looks a bit like a crumpled baked potato but measures a whopping 28 by 18 centimeters.

For years, scientists have examined the fossil to no avail, until in 2018 a paleontologist suggested that it could be an egg.

A gigantic discovery

This was not the most obvious assumption given its size and appearance, and there was no skeleton inside to confirm it.

Analysis of the fossil sections revealed “a layered structure similar to a soft membrane and a much thinner hard outer layer, suggesting it was soft-shelled,” said Legendre.

Chemical analyzes have shown that “the eggshell is distinct from the surrounding sediments and was originally a living tissue.”

But that has left other mysteries to unravel, including which animal has laid such a huge egg – only one larger one has been found, produced by the now extinct elephant bird from Madagascar.

The team believes that this egg was not from a dinosaur – the types living in Antarctica at the time were mostly too small to have produced a mammoth egg, and those large enough spherical rather than oval.

Instead, they believe it was from some sort of reptile, perhaps a group known as the Mosasaurs, which was common in the area.

Soft-shelled dinosaur eggs

The document was published in Nature along with a separate study that argues that it was not only ancient reptiles that laid soft-shell eggs – dinosaurs too.

For years, experts have believed that dinosaurs only lay hard-shell eggs, which were all that had been found.

But Mark Norell, curator of paleontology at the American Museum of Natural History, said that the discovery of a group of fossilized embryonic dinosaurs from Protoceratops in Mongolia had made him reconsider this hypothesis.

“Why do we only find dinosaur eggs relatively late in the Mesozoic and why only in a few groups of dinosaurs,” he said.

The answer, he theorized, was that the first dinosaurs laid soft-shelled eggs that were destroyed and not fossilized.

To test the theory, Norell and a team analyzed the material around some of the skeletons of Protoceratops in the Mongolian fossil and another fossil of two apparently newborn Mussauri.

They found chemical signatures showing that the dinosaurs were surrounded by soft, leathery eggshells.

“The first dinosaur egg was soft-shelled,” Norell and his team conclude in the newspaper.

Norell’s discoveries may have implications for the fossil once called “The Thing” – which is now known as Antarcticoolithus, according to a review of studies published in Nature.

They “could involve some form of dinosaur like the proud parent,” wrote Johan Lindgren of Lund University and Benjamin Kear of Uppsala University.

“Hopefully future discoveries of equally spectacular fossil eggs with intact embryos will solve this challenging puzzle. “



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