From what has been examined so far, there are evidence that at the end of the Cretaceous period a very large asteroid or comet stuck the Earth. The impact was where modern day Yucatan is located, and it released such an enormous energy that it managed to change the face of the Earth. The explosion itself managed to kill off pretty much everything nearby, but there was also a very hot wave that circled the whole planet. Enormous amounts of dust and ashes were released into the atmosphere that blocked the Sun, and the volcanoes all over the globe were triggered. This caused major climate and environmental changes, leading to a mass extinction, with the most noticeable victims being the dinosaurs.
In a survivable cold environment, an ectotherm is more likely to survive an extended period of food deprivation than would an equally sized endotherm because the ectotherm is using a little amount of its energy for temperature regulation.<span />
