250-million-year-old fossil proves mammal ancestors laid eggs

image via New Scientist

April 15, 2026, 2:15 PM

• •Fossil analysis reveals mammal ancestors laid eggs.
• •Lystrosaurus, a survivor of mass extinction, likely laid eggs.
• •Large eggs may have aided survival during harsh conditions.
• •The research provides context for species survival in a changing world.

A 250-million-year-old fossil of a Lystrosaurus embryo provides the first direct evidence that mammal ancestors laid eggs. This discovery addresses a long-standing question about the reproductive biology of these ancient creatures and their ability to thrive after a mass extinction. The study reveals that the Lystrosaurus, which survived the Permian mass extinction, likely laid large, leathery eggs, a trait that may have helped them endure harsh environmental conditions. The findings offer insights into how species might respond to environmental stress in today's changing world.

Read original article