Summary
The cause of mass extinction that ended the Cretaceous and marked the beginning of Paleogene is still a mystery. There two scenarios that could of cause it, scenario number one could be result from asteroid or comet that took out the dinosaurs or scenario number two could result from massive volcanism. Both scenarios can cause skies to be choked with debris that can starved Earth from getting its energy from sun and causing destruction of the entire food chain. This can lead interrupting photosynthesis that plants or organisms use to convert light energy into chemical energy where it can be later release to fuel the organism's activities. Once the dust has settled in, the greenhouse gases would be locked in the atmosphere which will cause the temperature to drastically increase.