Fossils in Morocco reveal the astounding diversity of marine life 66 million years ago, just before the asteroid hit

Sixty-six million years ago, the Cretaceous period ended. Dinosaurs disappeared, along with around 90% of all species on Earth. The patterns and causes of this extinction have been debated since paleontology began. Was it a slow, inevitable decline, or did the end come quickly, driven by a sudden, unpredictable disaster?