The mass extinctions have had detrimental role when it comes to the evolutionary patters and which organisms prosper, and on the other side which ones are gone forever. There have been numerous extinctions, some being much more extreme than others, but nonetheless they have all reshaped the ''playing ground'' for the organisms. Before a mass extinction occurs, there are lot of species living on land and in water, dominating the Earth by holding the highest niches in the food chain hierarchy, stopping other organisms to develop further as well. Then a mass extinction occurs, be it because of dramatic climate changes, impact with asteroid or comet, intense supervolcano activities, and those sudden changes manage to destroy big portion of the living organisms, with the ones that have been the largest and dominant usually being the most affected. That opens up the gate for the smaller organisms that lived in their shades to prosper as the niches have been left empty, so they quickly diversify and some of them manage to become the dominant ones, and the process continues. This happened with the sinapsids that dominated the Earth by died out because of mass extinction, the dinosaurs benefited from it so they became dominant while the mammals lived in their shades, then the dinosaurs had the same faith as the sinapsids, so the mammals took over.
