Overview
- The peer-reviewed study in PLOS ONE, released Thursday, April 9, identifies the first confirmed egg from a mammal ancestor using a 250-million-year-old Lystrosaurus embryo.
- High-resolution CT and synchrotron imaging at the European Synchrotron Radiation Facility non-destructively exposed a tightly curled skeleton hidden inside a rock nodule from South Africa’s Karoo Basin.
- Scans showed the embryo’s lower jaw halves were not yet fused, a trait seen in bird and turtle embryos, which indicates the Lystrosaurus died in the egg rather than after hatching.
- The team infers soft, leathery shells and relatively large eggs for body size, which would reduce water loss and yield precocial young able to feed and flee soon after hatching in dry post‑extinction landscapes.
- The findings inform when lactation and live birth evolved, with researchers proposing lactation may have begun as moisture‑secreting care for eggs, and they plan follow-up work on the origins of milk and viviparity; the specimen was first spotted in 2008 by fossil finder John Nyaphuli.