Before an asteroid completely changed the course of Earth’s evolutionary trajectory, the world was filled with scaled and feathered dinosaurs, web-winged pterosaurs, and, as a new study describes, precursors to modern mammals that eked out existence in burrows they dug into the Cretaceous...

Before an asteroid completely changed the course of Earth’s evolutionary trajectory, the world was filled with scaled and feathered dinosaurs, web-winged pterosaurs, and, as a new study describes, precursors to modern mammals that eked out existence in burrows they dug into the Cretaceous...