Re: DINOSAUR digest 1201

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

Nomen wrote:

> "James R. Cunningham" <jrccea@bellsouth.net> wrote:
>
> >>>the oxygen content of the somewhat more dense
> atmosphere was about 25%, which is about 25% higher than now, that it
> was already falling toward the present level, and had been doing so
> for some time.>>>
>
> I understand the oxygen content of the atmosphere at present to be
> about 21%.

20.9 %

> If the O2 content of the Cretaceous were 25% (and amber studies are
> highly questionable in this regard),

I agree

> it is still no 25% higher than
> what we have now; it is about 4% higher.

'Fraid not.  0.25/0.209 = 1.196 or 19.6% higherI should have done the
arithmetic rather than saying 'about'.  Dudley's graph shows the peak
early in the Tertiary at 26%, which would be 0.26/0.209 = 1.244 or 24.4 %
higher.  The increase in partial pressure is what counts.  I still should
have done the arithmetic.

> I think.
>
> John C. McLoughlin
> Taos, New Mexico
> USA