Did the Cambrian explosion really happen?

[admin]

Something unique does seem to have taken place during this time when so many animal groups first appeared, but it's not an open-and-shut case.

Did the Cambrian explosion really happen? : Read more

 

[Broadlands]

By comparison with the very long previous periods before the Cambrian it was clearly a massive increase in the number and diversity of megascopic sized multicellular animals, especially those with carbonate shells...the Metazoa, minus the vertebrates with phosphate minerals instead of carbonates. Another major evolutionary breakthrough?

 

[BILL ATKINS]

I was walking in Khor Kalba when I noticed that where the water cut through the rock there were black layers filled with dead shellfish. I realised whenever there had been an oil spill there had been an explosion of death. Something must have happened that caused a diversity of life forms to be fossilized at the same time. The Cambrian explosion was not an explosion of life- but of death. Living organisms avoid the conditions that would fossilize them if they can.

 

[Broadlands]

I was walking in Khor Kalba when I noticed that where the water cut through the rock there were black layers filled with dead shellfish. I realised whenever there had been an oil spill there had been an explosion of death. Something must have happened that caused a diversity of life forms to be fossilized at the same time. The Cambrian explosion was not an explosion of life- but of death. Living organisms avoid the conditions that would fossilize them if they can.

The black shales and carbonate shells are the result of the death of organisms but without enough of the usual recycling of their biomass by oxygen in aerobic respiration. Carbonate shells are resistant to that natural process and are preserved in the rocks. The Cambrian "Explosion" was both.