Overview
- A peer‑reviewed PLOS ONE study reports embryonic Lystrosaurus preserved inside eggs, giving the first confident proof that some mammal ancestors laid eggs.
- Researchers from the University of the Witwatersrand and the European Synchrotron used high‑resolution CT and synchrotron X‑rays to examine the rare specimens.
- The embryos show an unfused lower jaw and a curled posture, clear signs of in‑egg development within soft, leathery shells that rarely fossilize.
- The key fossil, found in South Africa’s Karoo Basin in 2008 by John Nyaphuli, includes a skull about 1.7 inches long consistent with an embryo.
- The team infers large, yolk‑rich eggs that produced self‑sufficient hatchlings, a strategy they propose helped Lystrosaurus survive the end‑Permian mass extinction.