How does biodiversity occur?

What events occur, relating to biodiversity, which occur following a major extinction event?

• Answer:

  An extinction event wipes out a large portion of organisms and various species, so biodiversity falls dramatically. Extinction events aren't an instant thing, so this dip can exist for some time, but following that organisms that have survived are left in a very changed biome. There are new niches available for surviving species to step into. Perhaps top predators are now extinct and a population can expand, or another organism that used to compete for the same resources is no longer around. Ultimately following an extinction event there is an explosion of biodiversity increase. With the last major extinction 65 million years ago and the demise of the age of dinosaurs there was huge opportunity for mammals to evolve and diversify into the diverse spectrum seen today. Sometimes the rebound process can take millions of years