The famous Cambrian Explosion- a rapid diversification of animal groups about 550 million years ago- assumes a rather diminished significance when mapped to the full Tree of Life.
update: yes, I made the diagram myself, by modifying this.
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So what do you see? A groove and some lines? Truth be told, this is possibly the oldest recorded chordate fossil (or, should I say, one of a number of seventeen specimens of same). It dates from the pre-Cambrian - i.e. before 543 million years ago - during a period known as the Ediacarian. Found by…
So what do you see? A groove and some lines? Truth be told, this is possibly the oldest recorded chordate fossil (or, should I say, one of a number of seventeen specimens of same). It dates from the pre-Cambrian - i.e. before 543 million years ago - during a period known as the Ediacarian. Found by…
Joe Carter and PZ Myers have been having a little exchange over some claims in the new paper by Stephen Meyer of the Discovery Institute, a paper that has prompted quite a bit of discussion. I jumped into that discussion briefly in a comment on Joe's page and I'm posting this as a follow up to that…
New research published in Science on the origins of multicellular life reveals an interesting pattern. The Cambrian Explosion may have been samosamo.
What is evolution about? Why are there different species, rather than just one (or a few) highly variable species? Is there a close…
That's a very nice illustration to put it in perspective. Thanks!
I have briefly seen videos on youtube about the subject of the cambrian explosion, And I had a question burning in my head. Why was the cambrian explosion a threat to the darwinian theory?
Maybe, the cambrian explosion is just a metaphor for the evolution and advancement of new forms with complex body parts that simply are modified ontogenetically through natural selection and mutation.
The reason why the Cambrian event may be problematic for Darwinian Evolution is that within canonical Darwinian theory is the assumption that phylotypic change occurs gradually, and is selected at each change. For the changes that occurred around the Cambrian Event, hundreds of millions of years would be required if later evolutionary changes scale linearly in time. Niles Eldridge et al proposed punctuated evolution which allows for rapid phylotypic change spaced with phylotypic stasis, one of the causes is hyppothesized to be geographical isolation which is often associated with an extinction event.
The systematics plot above is a bit misleading in that the large blue branch is all bacteria. I don't think that it would come as a shock to anyone that there are many more species of bacteria than metazoa. The Cambrian event affected the multi-cell body plans, and in a very significant way. Its effect on bacteria is not preserved in the fossil record. Therefore, to indicate that the Cambrain even affected only the branch indicated is not positively supported in the fossil record.