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Re: extinction by suffocation?!
I just happened to see a partial of what you are talking about.
some gas trapped in amber was analyzed to be approximately 35% oxygen. This
was from the time of the dino's, Jurassic I beleive. So the theory goes that
due to oxygen enriched atmosphere, it would have been easier for the dino's to
breathe. However, when the oxygen levels decreased due to volcanic activity,
the work of breathing increased to such a level as to cause the demise of the
larger dino's without diaphragms. Since they had a greater metabolic activity
than the smaller reptiles they couldnt survive. The mammals with were able to
survive due to diaphrams to aid in respiration.
I can see how some of this may be viable as a concept, but really need
more info on this. One thing is may explain, is how the large sauropods were
able to get enought oxygen through those large necks. A greater percent of
oxygen in the atmosphere, would certainly reduce the work of breathing.
However, a decline in the Fi02 (percent of inspired oxygen) over millions of
years, would, I would think, be adjusted to by the dino's through the
evolutionary processes that allowed them to come about in the first place.
Anyway, it makes for some great thoughts and discussions!
St. Louis Institute for Paleontology