RE: Oxygen level in Mesozoic - LONG

["Allan Edels" <edels@msn.Com>]

Jim (et al):

We've had this discussion before on list (AND I QUOTE MY REPLY TO YOU
[Jim] THEN [1999] :-) ):  

        "    I guess that 35% would be the upper limit, since any
references I've
        ever seen regarding potentially higher Oxygen levels all use
that as the
        highest level (I know  - pure speculation).

            Of course, the "spontaneous combustion of the biosphere" is
also
        speculation (since there is no known occurrence of it).  It
reminds me of the
        fear that some of the Manhattan project scientists had, namely
that the
        detonation of the Atomic Bomb would cause a chain reaction
leading to the
        entire atmosphere combusting.   They still exploded it
anyway......"

Quoting from The Journal of Experimental Biology 201, 1043?1050 (1998):
"ATMOSPHERIC OXYGEN, GIANT PALEOZOIC INSECTS AND THE EVOLUTION OF AERIAL
LOCOMOTOR PERFORMANCE"  ROBERT DUDLEY, Department of Zoology, University
of Texas, Austin, TX 78712, USA and Smithsonian Tropical Research
Institute, PO Box 2072, Balboa, Republic of Panama; 
e-mail: r_dudley@utxvms.cc.utexas.edu ;  Published on WWW 24 March 1998.

        "Concomitant with this reduction in carbon dioxide
        concentration, the oxygen concentration of the late Paleozoic
        atmosphere may have risen to as high as 35 % (Berner and
        Canfield, 1989; see Fig. 1), a remarkable value compared with
        the 20.9 % of the contemporary atmosphere. This elevation of
        oxygen partial pressure occurred against the background of a
        constant nitrogen partial pressure (Hart, 1978; Holland, 1984),
        yielding an increased total pressure of the atmosphere.
        Atmospheric oxygen concentrations are unlikely to have
        exceeded 35 %, as this value represents an approximate
        threshold for spontaneous combustion of the biosphere (Watson
        et al. 1978; Kump, 1989). "

You [Jim] had referred to this article back in 1998.
 
Even though the data from amber is questionable, the speculations are
still enticing.

Allan Edels 

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf
Of James R. Cunningham
Sent: Monday, August 05, 2002 11:51 PM
To: edels@msn.Com; dinosaur@usc.edu
Subject: Re: Oxygen level in Mesozoic - LONG

Isn't 35% about the fraction at which spontaneous combustion of the
biosphere would be expected?
Jim

Allan Edels wrote:

> "    Hengst and others (1993, 1996) demonstrated that a large long
> necked sauropod such as the Tithonian _Apatosaurus_ required an oxygen
> content
> in the atmosphere of about 35% to function at any level above a very
slow
> walk, slower than the rates deducted from trackways.