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.
Researchers have found evidence suggesting that intelligence evolved independently in birds and mammals, rather than being inherited from a common ancestor. This indicates that complex neural circuits supporting cognition arose multiple times in vertebrates.
