From ABC Science, 15 February 2017:
The discovery of a fossil of a pregnant marine reptile has provided the first evidence that an ancestor of modern-day birds and crocodiles gave birth to live young.
The fossil of the long-necked Dinocephalosaurus, which swam the seas during the Middle Triassic period around 245 million years ago, was unearthed by an international team of scientists in south-west China.
Inside the fossil was a much smaller fossil of the same species positioned in a way that suggested it was an embryo rather than the remains of prey, according to a paper published today in Nature Communications.
The marine reptile came from a group called the Archosauromorphs, which evolved 260 million years ago and includes modern-day birds and crocodiles, as well as extinct dinosaurs and pterosaurs. Read more.