In Cambrian Times

Question

In Cambrian times
A) All of the phyla that lived failed to survive to the present
B) No bilateral groups had arisen as yet
C) Nearly all of the fossilizable living phyla had appeared by then
D) None of the above

Accepted Answer

During the Cambrian period, which began around 541 million years ago, there was a remarkable diversification of life known as the Cambrian explosion. This event saw the rapid appearance of most major animal phyla, as well as the first appearance of many groups of organisms that would become important in later geological periods. This means that nearly all of the phyla that are capable of being fossilized (those with hard parts) had appeared by the end of the Cambrian period.