Scientists from the University of Witwatersrand (South Africa) and the ESRF discover the first-ever egg of a mammal ancestor, a 250-million year-old proto-mammal embryo, with the help of the ESRF. The results are out now in PLoS ONE.
A new discovery is shedding light on one of the greatest survival stories in Earth’s history, and answering a decades-old scientific mystery. Lystrosaurus, a hardy, plant-eating mammal ancestor, rose to prominence in the wake of the End-Permian Mass Extinction some 252 million years ago, the most devastating extinction event our planet has ever experienced. While countless species vanished, Lystrosaurus not only survived, but thrived in a world marked by extreme environmental instability, intense heat, and prolonged droughts.
Now, new research published in PLoS ONE reveals a discovery that sheds new light on our understanding of this iconic survivor. An international team led by Julien Benoit, Jennifer Botha (Evolutionary Studies Institute, University of the Witwatersrand, South Africa), and Vincent Fernandez (ESRF ) has identified, for the first time, an egg containing an embryo of Lystrosaurus, dating back approximately 250 million years. This rare fossil represents the first-ever egg discovered from a mammal ancestor, finally answering a long-standing question: Did the ancestors of mammals lay eggs?
The answer is yes.
The researchers suggest these eggs were likely soft-shelled, explaining why they have remained elusive for so long. Unlike the hard, mineralized eggs of dinosaurs, which fossilize readily, soft-shelled eggs rarely preserve, making this find exceptionally rare. But the implications go far beyond reproduction.
“This fossil was discovered during a field excursion I led in 2008, nearly 17 years ago. My preparator and exceptional fossil finder, John Nyaphuli, identified a small nodule that at first revealed only tiny flecks of bone. As he carefully prepared the specimen, 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,” says Botha.
Read more on the ESRF website
Image: The egg photographed in the control room of the ESRF