Pennsylvanian Extinction Query

["Steve Brusatte" <dinoland@lycos.com>]

Hey,
I apologize for a question that may appear to be off topic, but I do have a 
quick query regarding the Pennsylvanian (the period that holds my real 
interest...the Mesozoic is only my hobby!).

I'm currenly involved in a pretty exhaustive research project regarding Upper 
Pennsylvanian fossil faunas of Illinois.  It seems as if at a certain point in 
the rocks, a mass death assemblage of brachiopods is found.  Of course, this 
could be an artifact of preservation.  And, since I have no real scenario yet 
to explain it, I may be dead wrong.  However, this has gotten me thinking about 
a possible mini-mass extinction.  

Unfortunately, the best available data on mass extinctions (Raup and Sepkoski's 
work) only covers the past 250 million years.  I am working on a particular 
site that is somewhere from 290-300 million years old.  Although Raup and 
Sepkoski never mention the Pennsylvanian per se (in the papers I have read), if 
their 26 million year cycle data is correct, than an extinction of some sort 
would be predicted between 290-300 mya!  

So far, I have yet to find much information on a possible extinction.  I've 
tracked down as many papers on the subject that I can find (which is very 
limited because I don't have access to a scientific library as of yet).  
However, I can't really find any clear cut data that suggests a bona fide mass 
extinction during this time.

My off topic question is this: is there any real evidence for a mini-mass 
extinction about 290-300 million years ago, where is evidence of it preserved, 
and what exactly did it cause in relation to fossils and paleobiology?  

Any insights, both on list or off list, are appreciated!

Thanks,
Steve

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Steve Brusatte-DINO LAND PALEONTOLOGY
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