[reasonisfaith]

“What the evidence suggests is that very simple life did somehow begin billions of years ago and then very slowly complexified.”

You mean where the fossil evidence shows thousands of advanced species suddenly appearing at the same time, with practically previously existing species?

[reasonisfaith]

I meant to say practically NO previously existing species.

[BroJoeK]

reasonisfaith post #427: "You mean where the fossil evidence shows thousands of advanced species suddenly appearing at the same time, with practically previously existing species?"

Well, first, the Cambrian lasted about 55 million years, from 541 MYA to 485 MYA, which is hardly "sudden".

Second, "thousands of species" over 50 million years, but only about 600 genera alive at any one time (see post #294).
That's 600 total genera during the Cambrian verses today about 200,000 living animal genera alone.
So, more of a slow burn than "explosion"

Third, today there are about 36 different animal phyla.
From my post #347:

This chart lists all 36 animal phyla and shows their fossil origins:
1. 2 phyla -- Precambrian
2. 3 phyla -- early Cambrian
3. 10 phyla -- "Cambrian Explosion"
4. 3 phyla -- Post-Cambrian
5. 18 phyla -- no fossils found
6. 36 phyla -- total living animal phyla.

So, of 36 living phyla, 10 are first seen in the Cambrian Explosion, 8 more are first found before or after and 18 have never been found in fossils.

Fourth, what truly did change during the Cambrian Explosion was the first appearance of hard shelled creatures.
These fossilize more frequently and are what make many life-forms seem to appear "suddenly".