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Re: Mesozoic Oxygen

>S.S. Lazarus wrote:
>"Is there anyway to infer oxygen levels during the Mesozoic from the fossil
>The study in question, Hengst et. al. (1996), notes a number of ways that
>indirect evidence for varying Mesozoic oxygen levels have been detected,
>including analysis of the thickness of dinosaur eggshell (Erben et. al 1979)
>and analysis of gases trapped in amber air bubbles (Landis et. al. 1993). The

I would also make two comments.  First, this paper was presented in 1993
and represented my initial thoughts on respiration, atmospheric O2 and
activity, despite the recent publication date.  I have since changed some
of my views and thoughts as more experimental evidence has accumulated from
my laboratory experiments.  Some of these will be forthcoming shortly in a
paper on the evolution of dinosaur breathing.

Second, Landis' work has been highly criticized as being flawed but careful
experimental testing of each objection has continued to confirm that the
NITROGEN in the bubble is original atmospheric in source so it is presumed
that the O2 is also original.  This comes the closest to direct evidence
but still suffers from a problem with testing for oxygen source while still
within the amber bubble.

I wish there was a direct way to do many of these dino things, it would
make my life a lot simpler.

Happy Thanksgiving to all the dinopeople out there.


Richard Hengst
Biol. Sciences
Purdue Univ. / North Central
Westville, IN  46391
phone   219/785-5251
fax     219  785-5355
email   rhengst@purduenc.edu