Why are mass extinctions
important in earth's history?

At the most basic level, mass extinctions reduce diversity by killing off specific lineages, and with them, any descendent species they might have given rise to.

Explanation:

In this way, mass extinction prunes whole branches off the tree of life. But mass extinction can also play a creative role in evolution, stimulating the growth of other branches.

c. seafloor spreading occurs.

d. crust becomes molten rock.

e. denser plates slide under lighter plates.