At 09:13 AM 1/19/2016, Warren D Smith wrote:

--I don't believe you. If oxygen levels were high enough to sustain a many year long planet wide fire, then one would have got started without need of a meteor. Lightning, etc.

True, but there are fires, and there are FIRES. Dresden-type fires are substantially different from regular fires, in that they create their own winds & weather; the scale of the fire is important -- a planetary scale fire would be substantially different from even a Dresden-type fire. The impact 66mya lowered sea levels around the world by at least a foot, thus exposing a lot more carbon that had previously been covered with water. Anyhow, despite criticizing your argument, oxygen levels were indeed higher and lower in the past.

https://en.wikipedia.org/wiki/Geological_history_of_oxygen and I do not know how solid their reconstruction of the past is, but they have one.

Originally there was no O2. "The maximum of 35% was reached towards the end of the Carboniferous period (about 300 million years ago), a peak which may have contributed to the large size of insects and amphibians at that time."

I'm disagreeing with these conclusions, which are sketchy, at best.