This 100 million-year-old snake had hind legs and a lost bone that changes evolution

A remarkably preserved fossil from Argentina is helping scientists sharpen the picture of how snakes evolved. The specimen belongs to Najash rionegrina, an ancient rear-limbed snake that lived nearly 100 million years ago. Its skull shows that these early snakes still had a cheekbone, also called the jugal bone, a feature that has almost completely disappeared in living snakes. The 2019 study added an important piece to a fossil record that had long been too sparse to clea...