When Did Animals Start Giving Birth to Live Young? This 236-Million-Year-Old Fossil Might Rewrite Mammals' Evolutionary History
A bone feature found in a mammal ancestor hints that the creature was relatively large as a newborn, more in line with the size of a creature birthed live than hatched from an egg. Still, it provides only indirect evidence
We haven't written up this one. Smithsonian has the full story — the link below goes straight to it.