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April 11, 2026
Mammal ancestors laid eggs, a fossil analysis shows
Scientists have confirmed mammal ancestors laid eggs after a 250 million year old Lystrosaurus fossil revealed the first direct evidence
TL;DR
- A 250-million-year-old Lystrosaurus fossil shows that early mammal ancestors laid eggs.
- The discovery was made possible by advanced synchrotron X-ray CT scanning.
- Lystrosaurus was a herbivorous mammal ancestor that survived the End-Permian Mass Extinction.
- The eggs were likely soft and leathery, and rarely preserve as fossils.
- Lystrosaurus likely did not produce milk but laid large eggs, and its young hatched at an advanced stage of development.
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