Importance of major mass extinction

Describe the importance of some of the major mass extinction events that have occurred on Earth. Include in your description what caused the event (if known), and what its major consequences were

Cretaceous-Paleogene

Perhaps the most famous of the major mass extinctions is the Cretaceous-Paleogene, or K–Pg, extinction, which occurred some 66 million years ago. It marked the end of about 67 percent of all species living immediately beforehand, including the non-avian dinosaurs.