[djf]

I had read somewheres that O2 content might have been as high as 30 percent during the time of the great lizards.

I had an email contact last week with a scientist who studies these things and asked him about dissolved O2 in the oceans. He said that's fairly negligible amount. But water high in the atmosphere gets broken up into Hydrogen (which escapes) and Oxygen which stays behind.

Don't know if there is any reliable estimate of how much. But it's interesting that solar weather can have that kind of effect.

[grey_whiskers]

But 55 million years later, atmospheric oxygen levels sank to 10 percent to 13 percent.

And you mentioned 30 percent.

What can we say about the O₂ fluctuations except:

Bush's Fault^TM!

Cheers!

[SunkenCiv]

:') Oxygen in the oceans is replaced at depth by, hmm, hydrogen sulfide I think, which is (if memory serves) a byproduct of bacterial activity at depth (land and sea). Oxygen is pushed into and out of compounds (such as water and various sugars, both of which are produced in photosynthesis; and CO2 through respiration) by biological activity.