[extropy-chat] Evolution questions

[Robert Bradbury]

What are you looking for?  According to Wikipedia, the Hadean era is before
3800 MYr ago while the Cenozoic eon is after the C-T extinction event
65.5Myr ago.  That is a huge range and misses the Archean and
Proterozoic eras
as well as most of the Phanerozoic era.  I'm not sure of the exact dates but
I think there were at least to snowball earth's during that time frame.

I'd suggest you start with the Wikipedia  "Geologic timescale" entry and
work your way into the "Extinction event" entry.  As it discusses there may
have been anywhere from 5 to 20 extiction events.  Most of them are very
poorly documented because they happened before hard shelled or bony fossils
developed at the start of the Phanerozoic ~550 million years ago.

What can be documented with really hard evidence is only the last 10-15% of
the age of the Earth.  Everything during the earlier years is a matter of
rare geologic evidence, running computer simulations and "what if" analysis.

Robert

On 3/4/06, Anne-Marie Taylor <femmechakra at yahoo.ca> wrote:
>
> I have a few questions regarding evolution between the Hadean eon
> to the Cenozoic eon.  If anybody can help me out, it would be much
> appreciated.  You can e-mail me offlist.
>
>
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