Mammal ancestors laid eggs, and this 250-million-year-old fossil finally proves it

A new fossil discovery is bringing fresh insight into one of the most remarkable survival stories in Earth's history while also resolving a scientific mystery that has puzzled researchers for decades. Lystrosaurus, a tough, plant-eating ancestor of mammals, became one of the dominant species after the End-Permian Mass Extinction around 252 million years ago. This event wiped out most life on the planet. Despite extreme heat, unstable conditions, and long-lasting droughts, ...