<human>:  When did the dinosaur extinction happen?
<bot>: The extinction of the dinosaurs is generally thought to have happened 65 million years ago. The extinction of the dinosaurs is a popular topic in science education, and there are many different theories about what caused the extinction of the dinosaurs. The most widely accepted theory is that a large asteroid hit Earth 65 million years ago, and this is the cause of the extinction of the dinosaurs.