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 == P-T Extinctions == 

 In relation to your recent additions to Permian-Triassic extinction event, it may be useful to review Wikipedia:Neutral point of view which explains how Wikipedia articles should be written on subjects which may be disputed.  Overall you did a very good job with the hydrogen sulfide material, but it would be useful to identify which parts of the chain of events are likely to be disputed by other scientists.  Also, the tone of your writing skews a little bit towards saying "this is the truth" rather than "this is new plausible idea that has not yet been adopted by the scientific community as a whole".  

 Of course, these issues can occur even in the writing of experienced editors, so don't feel bad, but it is important to think about the best way to frame the scientific debate without trying to unfairly take sides in issues that the scientific community has yet to resolve.