Cambrian Explosion; the great unconformity (Introduction)

by dhw, Tuesday, May 01, 2012, 16:57 (4568 days ago) @ David Turell

DAVID: Another version of this theory. I've actually touched the great unconformity in the Grand canyon during a lecture by a recognized world expert on Canyon geology who was rafting with us. 750 million years of rock is absent, but is present in other parts of the world to let us recognize the absence in the canyon. The sediment formation in the cambrian as a result may offer a substrate for the development of the cambrian organisms, but the drive for the changes came from the genomes, not the sediment.
 
http://www.sciencedaily.com/releases/2012/04/120418131429.htm-These theories are certainly coming in thick and fast. Again, I was struck by a particular observation:-"It's likely biomineralization didn't evolve for something, it evolved in response to something ... in this case, changing seawater chemistry driving the formation of the Great Unconformity." Yet again, as in the brilliant Shapiro article and in previous Cambrian theories concerning the increase in oxygen, the emphasis seems to be on innovation springing from organisms responding to environmental influences (as opposed to Darwin's random mutations being tested by the environment). I'm also increasingly attracted to the idea that gaps in the fossil record are in themselves informative. Maybe they aren't gaps at all. Maybe the old adage 'Natura non facit saltum' is in the process of being disproved. After all, innovations can only take place in individual living organisms, and if they don't work, the organisms probably won't survive.