Re: Oxygen level in Mesozoic - shorter

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Allan Edels" <edels@msn.Com>
Sent: Tuesday, August 06, 2002 1:58 AM

> RE-POST:
> ************************************************************************
>     Just a few quotes:
> -------
>     "A few of the arguments that the gas in amber bubbles is really
> fossil air are given here, for the others see Landis and others 1996.
>
> *    [...]

Impressive. -- I'd think that keeping oxygen within a combustible substance
should, over geological time, wreck at least the nominal carbon dioxide
content which is measured much more finely; it certainly shouldn't produce
additional oxygen.

> [...] cause respiratory stress in the exact time
> interval when metabolic needs were increasing because of falling global
> temperatures.  The second type may have been the ultimate cause for most
> of the terminal Cretaceous extinction."

Except that there were no falling global temperatures. :-)

> "    Hengst and others (1993, 1996) demonstrated

that it's possible to publish big blunders. They didn't even get the idea
that an air-sac system could have been present!

> [...] _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.

So either there were 40 % oxygen or some basic assumption is wrong... Indeed
their central argument are the relatively tiny nostrils of *Apatosaurus*. DA
writes that the nostrils of elephants are just as tiny, so Hengst et aliorum
conclusions (of course they thought they had proven sauropod ectothermy,
BTW) are falsified.

> Our measured levels of
> [B]arremian and Aptian oxygen are 28% and 29% respectively.

Similar to the 26 % I mentioned.

>  It thus is not very surprising that our
> only surviving Aptian sauropods are both small, and
> short-necked,

Especially *Sauroposeidon*. What a beautiful fact destroyed that ugly
hypothesis... :-)

> "*    The increased Carbon Dioxide (up to 6 times the present value)
> caused
> the Cretaceous Greenhouse effect, and major global warming."

Well... the same temperatures were normal in the Paleocene and Eocene when,
except for the Pal-Eocene boundary, CO2 levels are no longer thought to have
risen above 500 ppm. (Gives interesting prospects about the very near
future...)

> *    Dinosaurs required 40 breaths to fully replace the air in their
> lungs.

Because they had exactly the same lungs as... what? Normal lizards?

> *    Mammals and Birds only require 7 breaths to completely replace the
> air in their lungs.

Mammals and birds require the same??? Strange. Did they at least mean lung +
air sac system volume in birds?

> Some additional notes:
>
>     The paper indicates that the O2 level during the Permian was 14%,

The guesstimates I know say that about 15 % was to what the levels dropped
in the P-Tr mass extinction.

>     Top-most Hell Creek                    65.2 mya         31%
>
>     AFTER K/T Boundary                  65 mya             29%

Oh, what a jump. What is the oxygen content today on Mt. Everest where
recreation is impossible for humans?

>     Eocene                                          50 mya
> 16%

Illogical... there were tropical and paratropical rainforests on almost the
entire land area that should have produced a bit more.