At random intervals, the Paleocene Eocene Thermal Maximum of about 55 million years ago pops up in these threads like this. I have been arguing here that following big tectonic events, the oceans may have dramatically redistrubuted, causing massive sea floor methane hydrate release events. I should have payed better attention to the publications, this has been around quite a while: Hence the tectonic element is covered now. More recently http://www.science.usyd.edu.au/news/pdf/whittaker.pdf [Broken] popped up: Since an earlier date for that event was estimated 43 million years ago, it could be that the age estimate is rather uncertain. Hence I have asked ms Whittaker if the estimated date could also be 55-56 million years ago. That would make things fall into place.