A 250-million-year-old fossilized embryo from South Africa is the oldest evidence that mammalian ancestors (therapsids like Lystrosaurus) were egg-laying. Using synchrotron X-rays, researchers found jaw developmental traits confirming it died before hatching.
This discovery clarifies the reproductive biology of these ancestors, suggesting they used yolk to nourish embryos instead of milk. The large, leathery eggs may have offered a survival advantage against desiccation during the "Great Dying" mass extinction.
This find offers significant insights into the evolutionary transition toward modern mammalian reproduction and lactation.
This discovery clarifies the reproductive biology of these ancestors, suggesting they used yolk to nourish embryos instead of milk. The large, leathery eggs may have offered a survival advantage against desiccation during the "Great Dying" mass extinction.
This find offers significant insights into the evolutionary transition toward modern mammalian reproduction and lactation.
Within the last 200 years, we’ve discovered about two dozen species of hominins in Europe, Africa, and Asia—which you can see laid out in this map.
