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Re: Atmospheric O2 Levels and Dinosaur Growth

In a message dated 95-09-08 21:53:24 EDT, you write:

> Wouldn't a severe fluctuation of oxygen affect plant life?  Wouldn't 
>     we see more dead plants since, conversely, there would be less carbon 
>     for the plants to use?

There does seem to be another problem here.One of volume. The earths
atmosphereic volume is fixed.  Further, the global abundance of  atmospheric
gases must also have been fixed (in equilibriumwith each other). Let's also
fix the thermal radiation flux (but likely at a higher value than today due
to astronomical, insolation,  factors not discussed here). The the Ideal Gas
Law (PV=nRT) seems to indicate that only the pressure would increase. In my
view, you cannot raise both CO2 and O2 levels because under the conditions
above, (n, V and T being constant), increasing the percent abundance of one
gas must result in a decrease in the percent abundance of the other gas (in
moles of course). This has to do with partial pressure of each gas as well
contributing to the overall total atmospheric pressure. To account for both
CO2 and O2 levels then we would have to invoke some as of yet unidentified
mechanism of adiabatic expansion of the atmosphere, a more voluminous paleo-
atmosphere with a HIGHER average atmospheric pressure if you will.  It is
genearlly regarded that from the Carboniferous to the Eocene,
paleotemperatures and CO2 levels were much higher than at presesnt. Tropical
and subtropical climates extended well into northern latitudes. This is based
on paleobotanical studies and palynological studies.By inference we can
conclude that the earth had much more vegetative cover (forests, jungles,
mangroves etc)than exists today. Perhaps then, late Paleozoic through early
Cenozoic physics operated on equilibrium conditions much different (higher)
than todays to account for the higher molar amounts of both CO2 and O2!

                                          Thomas R. Lipka 
                                          Paleontological/Geological Studies