A quail-size fossil uncovered in China suggests birds evolved millions of years earlier than previously thought.

Baminornis has a pygostyle - a bone plate formed by fused vertebrae at the end of the vertebral column. "A short tail ending with a pygostyle is a universal feature of extant birds. It provides ...

It's not just tail length that matters, but how they end. Modern birds' tails finish with several vertebrae fused into a bone known as a pygostyle, and that of Baminornis zhenghensis was the same.