Mesozoic biosphere depth

[Larry Dunn <majestic_cheese@yahoo.com>]

Has it been possible to determine how "deep" the
biosphere was during the Mesozoic, that is, how far
under the earth's surface it "penetrated?"  

If so, was it substantially different than the present
earth biosphere?  And if so, what impact would this
have had on the animals occupying the surface?

=====
Larry

"I've been ionized, but I'm OK now."

http://members.tripod.com/~megalania/index.html

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