Nevertheless, recently the journal Nature attempted to provide a solution to the confounding dilemma:
“An evolutionary burst 540 million years ago filled the seas with an astonishing diversity of animals. The trigger behind that revolution is finally coming into focus.”
This time, the assumed “big trigger” is oxygen.
Nature quotes palaeontologist Erik Sperling (Stanford University, California) as saying:
“If oxygen levels were 3% and they rose past that 10% threshold, that would have had a huge influence on early animal evolution. There's just so much in animal ecology, lifestyle and body size that seems to change so dramatically through those levels.”
This will not solve anything, however. Any kind of life needs more than just water. And oxygen cannot give birth to complicated organisms.
What is needed is genetic information coded in a way that enables it to build functional multicellular animals. That is – and will forever be – beyond the power of Darwinian mechanisms.
Fox, Douglas. 2016.What sparked the Cambrian explosion? Nature 530, 268–270 (18 February 2016) doi:10.1038/530268a.