From: John K Clark (johnkc@well.com)
Date: Sun Aug 25 1996 - 22:59:07 MDT
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Damien R. Sullivan phoenix@ugcs.caltech.edu On Sun, 25 Aug 1996 Wrote:
>There's just 300 megayears between rock and fossils. It might
>be informative to consider what type of rocks are from then
It would be most interesting to know if liquid water existed at that time, but
unfortunately all rocks of that era have been badly deformed, metamorphosed
and intruded, making study of them much more difficult.
>eukaryotes need oxygen, and if they appear as soon as there's
>enough O2 in the atmosphere, well, there goes another part of
>the filter.
Some Eukaryotes need free oxygen, but for others it is a useless waste
product, it certainly is not a defining characteristic of them. If Robin is
correct and Eukaryotes evolved about 2 billion years ago and not 1.4 billion
as I said, then that would mean complex single cell life is easier to make
than I thought, but multicellular life is more difficult.
John K Clark johnkc@well.com
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