Talk:Cambrian explosion
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Not the real explosion.[edit]
IMHO, the Cambrian explosion wasn't the real explosion. The molecular evidence and now the fossil evidence are showing the actual explosion in life took place around 570 mya in the middle of the Vendian period. Before that point, the Ediacaran fauna is mainly simple cnidarian-like creatures. Starting ~575 ma, though, we begin to see the great diversification of the Ediacaran fauna, for example the 565 ma Mistaken Point biota in Newfoundland, from the heart of the "Avalon Explosion". We can even see the predecessors of the modern groups: Spriggia is possibly the root of the arthropods, Kimberella the molluscs, and I'll be damned if Vernanimalcula is not related to tapeworms. Even the enigmatic Placozoa may have a Vendian representative: the Dickinsonia. Molecular evidence also shows the rapid explosion from 575-560 ma. I am tempted to think that the Cambrian explosion wasn't an explosion at all: the real burst of phylum-level diversification would have been 30 million years before the start of the Cambrian. (Citations include The Ancestor's Tale by Richard Dawkins, http://www.peripatus.gen.nz/paleontology/Vendian.html#DrookFm, http://palaeos.com/proterozoic/neoproterozoic/ediacaran/ediacaran3.html, THE EDIACARA BIOTA: Neoproterozoic Origin of Animals and Their Ecosystems by Guy M. Narbonne, and The Avalon Explosion: Evolution of Ediacara Morphospace by Bing Shen et al.) Are my conclusions valid, or is there something I'm overlooking? I would greatly appreciate any assistance. The Heidelberg Kid (talk) 03:23, 26 May 2012 (UTC)
- 30 million years is not that much of a difference; the name still stands fine. --il'Dictator Mikal 03:31, 26 May 2012 (UTC)
One, 30 million years is actually a big difference: it's the same amount of time from the start to the end of the Silurian, which saw the land transformed from mostly barren lifeless rock to mostly ecosystems of mosses, ferns, primitive trees, and arthropods of various sorts. Two, I know that not everything appeared in the Avalon explosion in the same way not everything appeared in the Cambrian: I've looked at pictures of pre-Avalon fossil cnidarians and sponges. What I mean is, the molecular evidence indicates that starting c. 570 ma, the bilaterians rapidly diversified over a period of 10-20 ma, to the point that the fossils and molecules show this rapid diversification from before (5 phyla: Porifera, Placozoa, Ctenophora, Cnidaria, Acoela) into the Arthropoda, Mollusca, Enchioderma, Hemichordata, Chordata, Nematoda, et cetera. So, my point remains. Am I overlooking something? (I do not want to hold dogmatically to any my claims. I just want to see if the previous explanation can accomodate new evidence before switching.) The Heidelberg Kid (talk) 16:12, 26 May 2012 (UTC)