Re: Oxygen level in Mezoic

["James R. Cunningham" <jrccea@bellsouth.net>]

Papers (which are rather speculative in my opinion) have indicated that the
nitrogen mass was about the same as now, and the CO2 level was several times
higher.  The higher oxygen percentage acted to increase the total pressure and
density of the atmosphere, so the big dragonflies would also have been flying at
a lower density altitude than now (greater density), due to the additional
oxygen.  The total amount of CO2 apparently wasn't great enough to substantially
affect the surface pressure and density.
Jim

David Marjanovic wrote:

> There once was a short article in New Scientist (maybe I can find it) on
> atmospheric oxygen through time. Says 35 % in the Carboniferous and Permian,
> then around the normal 21 % until the mid-Jurassic, then 26 % until the
> Eocene, then 21 again. I