The Cambrian Explosion and the Artifact Hypothesis

The Cambrian explosion was the first that got noticed as you say Darwin himself noticed that this was a problem. The earth is big, geologic time is essentially endless, there are fossils there, we just haven't found the intermediate forms. And the Cambrian explosion from our point of view has become even more explosive. There are more new forms of life, more new animal forms known now in that Cambrian explosion event than there were in Darwin's time.