From: CurtAdams@aol.com
Date: Thu May 09 2002 - 12:45:47 MDT
In a message dated 5/9/02 5:08:34, charlie@antipope.org writes:
>Well, that would actually provide one answer to the big puzzler: why
>did the earth support prokaryotes for about 2-3Gy before the eukaryotes
>showed up, then only 0.3-0.4Gy before multicellular life took off?
0.6-0.7Gy, actually. I favor the recently proposed "snowball earth" model.
Prior to the Cambrian - and at one point in the Cambrian - you find
glacial remodeling at the equator, suggesting the earth was frozen solid.
That would pretty much kill off any multicellular life. Such as was there
would have to be in the deeps of ocean (which remain liquid under thousands
of feet of ice) and would there would be no fossils now. Might explain why
the fossil record is only to 0.7 Gy but molecular evidence suggests
complex triploblast organisms go back more than 1 Gy.
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