An international team of researchers from the University of the Witwatersrand, in South Africa, identified the first egg with an embryo from an ancestor of the mammals. The discovery corresponds to a specimen of Lystrosaurusa herbivore that inhabited Earth approximately 250 million years ago.
This discovery, published in the scientific journal PLOS Onesolves a decades-old mystery about whether these distant relatives laid eggs. The fossil remained hidden because these animals probably had eggs of peel soft. Unlike the mineralized eggs of dinosaurs, these organic materials are rarely preserved over time.
The fossil originally appeared in 2008 during a field trip led by Professor Jennifer Botha. Preparer John Nyaphuli found a small nodule with tiny bone fragments. However, the technology at that time was insufficient to confirm that it was a baby inside its egg.
Using advanced synchrotron X-ray CT scans in France, scientists observed minute details of bone structure. Dr. Vincent Fernández explained that the scanning allowed us to capture critical levels of detail to understand the reproduction of these ancestors.
The tomography scans also revealed that the specimen’s lower jaw is made up of two halves. These pieces must fuse before the animal can feed. The fact that this union has not yet occurred demonstrates an important condition. The individual was unable to feed himself.
The study indicates that the Lystrosaurus It laid large eggs in relation to its body. These eggs contained a lot of yolk, which allowed the young to be born at an advanced stage of development. For this reason, it is suspected that these animals did not produce milkunlike current mammals.
The research highlights that these large eggs resisted the lack of water better. This trait was vital for surviving the intense heat and prolonged droughts that followed the Permian-Triassic mass extinction. He Lystrosaurus It dominated ecosystems thanks to rapid reproduction and accelerated growth.
Professor Julien Benoit noted that this historical milestone offers a perspective on the resilience biological response to extreme climate changes. Benoit believes that understanding how these organisms survived helps predict the response of current species to the global ecological crisis.
