Question

PLEASE HELP WILL GIVE MEDAL: Okay here's the thing.. I need to Describe the two most important events in the history of animal life that occurred at the beginning and at the end of the Paleozoic era. (keep reading.)

Answer 1

the answer is: At its beginning, multicelled animals underwent a dramatic "explosion" in diversity, and almost all living animal phyla appeared within a few millions of years. At the other end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all marine animal species.

(It's in the document my teacher wanted us to look at)

how do I reword this is the simplest way possible?