Mammal ancestors laid eggs – study (PHOTOS)

A recently analyzed fossil of a Lystrosaurus hatchling has helped solve a decades-old mystery

A recently analyzed 250 million-year-old fossil has shown that early mammals laid eggs, according to a paper published in the PLOS One journal on Thursday.

While some examples of egg-laying mammals exist today, such as the platypus and the echidnas, scientists have spent decades looking for proof of this in earlier ancestors.

According to South African Professor Jennifer Botha, one of the scientists behind the breakthrough research, the fossil was discovered in 2008, but could not be analyzed for years without cutting-edge and delicate scanning methods.

“It became clear that it was a perfectly curled-up Lystrosaurus hatchling. I suspected even then that it had died within the egg, but at the time, we simply didn’t have the technology to confirm it,” she said in a statement cited by phys.org.

With the use of advanced synchrotron X-ray CT scanning, which uses a particle accelerator to create extremely high-resolution non-destructive 3D images, the delicate fossil could be studied in depth.

Lystrosaurus was a herbivorous mammal ancestor which survived and then thrived in the tumultuous period after the End-Permian Mass Extinction around 252 million years ago, which is believed to have wiped out up to 96% of all marine species and 70% of land vertebrates on Earth. The catastrophe is theorized to have been caused by massive volcanic eruptions and resulting coal burning, which caused rapid global warming, and left a world of extreme heat and environmental instability.

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According to the research, Lystrosaurus eggs were likely soft and leathery. Compared to hard-shelled eggs, softer variants rarely preserve, making fossils extremely rare.

Judging by the development and properties of the hatchling, the Lystrosaurus likely did not produce milk but laid large eggs, which are more resistant to drying out in a hot, arid environment, according to Botha’s Witwatersrand University.

Its young likely hatched at an advanced stage of development, ready to feed themselves and thrive in the hostile world following the worst extinction event in history.