The discovery of a 250-million-year-old fossilized egg with a Lystrosaurus embryo provides the first direct evidence that mammal ancestors laid eggs.

Scientists have discovered a 250-million-year-old fossilized egg containing a Lystrosaurus embryo, providing the first direct evidence that mammal ancestors laid eggs. The rare find, likely a soft-shelled egg, helps explain why such fossils are seldom preserved and resolves a long-standing mystery about early mammalian reproduction. Advanced imaging revealed the embryo was still developing and unable to feed itself, offering insights into its growth and survival strategy. Researchers believe large, nutrient-rich eggs and early independence helped Lystrosaurus thrive in harsh conditions after a mass extinction. https://genus.africa/research-article/ancient-survivor-reveals-its-secret-first-ever-egg-of-a-mammal-ancestor-discovered/

Scientists have discovered a 250-million-year-old fossilized egg containing a Lystrosaurus embryo, providing the first direct evidence that mammal ancestors laid eggs. genus.africa/research-art... Ancient Survivor Reveals its S...

250-million-year-old fossil provides proof that our mammal ancestors laid eggs www.wbur.org/hereandnow/2026/04/21/fossil-mammals-eggs The fossil, found in South Africa, belonged to an embryo of the Lystrosaurus.