The Day the Mesozoic Died

The video says that an asteroid was the cause of the death of all dinosaurs because when it hit the ground it sent impact over the land. The impact was so large that it killed everything that was living at the time. The ash from fires and everything else covered the sun which caused the things that thrived on the light to die off because they didn't have the light anymore. They discovered this by finding evidence of things that could only be there if a huge impact had been caused like many different kinds of rock that came from different areas on Earth were all found in the same area. Also, as they look at the KT Boundary they find lots of dinosaurs and reptiles before it, but there is no sign of any of them after it. Which helped them come to their hypothesize that an asteroid hit the Earth and killed them all off.