How did dinosaurs die out?

Dinosaurs died out when the climate changed suddenly or an asteroid hit the earth.

Dinosaurs died out in the sudden change of temperature. Dinosaurs are warm-blooded animals. They have to expend physical strength to raise their body temperature in cold conditions, and their bodies are very huge. They are not suitable for keeping out the cold in caves. Continued cold weather may freeze to death.

75% of the existing species in the world died out in the disaster.