Just to put a bit of a context here, life exists on Earth for 4 billion years (single celled), and 1.5 billion years (multicellular) [1]. There were few mass ex

Just to put a bit of a context here, life exists on Earth for 4 billion years (single celled), and 1.5 billion years (multicellular) [1]. There were few mass extinction events in the history of Earth, at least 5 happened in the last 540 million years with up to 50% of life disappearing [2]. There were before periods with much more diverse life, than what we have now, so probably life before occupied the whole planet [3], obviously not all of that species left themselves in fossils, so exact numbers are a matter of big debates. [1] https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h... [2] https://en.wikipedia.org/wiki/Extinction_event https://en.wikipedia.org/wiki/Extinction_event [3] https://en.wikipedia.org/wiki/Cambrian_explosion https://en.wikipedia.org/wiki/Cambrian_explosion