VOA慢速英语:Dinosaurs Already Decreasing Before Asteroid Hit

extinct – adj. no longer exist, or alive

paleontologist – n. a person who studies the fossils of animals and plants that lived a long time ago, including dinosaurs

prime – adj. time when they are at their best

evolutionary - adj. changes and development over time

groundbreaking – adj. introducing new ideas or methods

fate – n. a power that is believed to control what happens in the future