<human>:  I have a question about the K-T mass extinction. Why did the dinosaurs die out?
<bot>: The K-T extinction was caused by a massive asteroid impact. The impact wiped out the dinosaurs and many other species. The asteroid was about 10 km in diameter and it hit Earth at a speed of about 30 km/s. The impact caused a global firestorm that lasted for about a year. The impact also caused a tsunami that reached heights of up to 20 meters.