There are multiple theories as to why dinosaurs died out, such as asteroid impact, volcanic activity, and climate change. There are many theories because none has been proven to be 100 percent certain as the reason for the dinosaurs’ demise.
The asteroid impact theory suggests that dinosaurs died in a massive extinction as a result of a large asteroid hitting the planet. Evidence that supports this theory includes the presence of a metal called iridium in places where dinosaur fossils have been found. Iridium is a rare metal that is not commonly found on Earth, but is a common material in asteroids. Scientists believe the impact from the asteroid could have lead to the development of tsunamis and forest fires, as well as creating a layer of dust and ash that blocked out the light from the sun, plunging the planet into darkness and cold.
Other theories suggest that there was an increase in volcanic activity around the time that dinosaurs went extinct and they believe this activity would have destroyed habitats and pushed enough ash into the atmosphere to affect the climate and destroy vegetation.
The climate change theory states that Earth's climate gradually became cooler and drier, and that dinosaurs could not adapt to the change, leading to their gradual extinction.
Religious theories support the idea that dinosaurs died during the great flood in Noah's time.
While the topic of how dinosaurs went extinct is still up for debate, discoveries of new fossils offer more information about how they lived.