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RE: walking on (post?) K/T eggshells



John Bois wrote:

> http://www.vertpaleo.org/bulletin/181.pdf
>
> Scroll to page 61.

And previously:

> As mentioned in the archives, the iridium layer in India is not 
> indicative of K/T boundary--i.e., the spike is _before_ 
> extinction: "...profuse  occurrence of (non-reworked) theropod 
> eggshells...in beds overlying the iridium-enriched levels.  

Firstly, can you be certain that teeth and eggshells of the non-avian
dinosaur variety were captured in sediment (and ultmately fossilized) soon
after they were shed/layed?  And I don't mean that they were reworked.  I
mean that these remains were exposed for many thousands of years before
being buried and the process of fossilization began.  I've heard of
subfossil remains (eggs and bones) from moa and elephant birds dating back
many millennia.

Secondly... so there was a lag between the iridium-producing impact and the
extinction of dinosaurs (and friends).  So what?  I don't believe anybody is
claiming that the impact was the direct cause of every dino dropping dead.
Rather, it set in motion a chain of events which culminated in the demise of
many groups of invertebrates and vertebrates.  I'm thinking along the lines
of a pervasive disintegration of pre-existing ecosystems, from the bottom
up.  




Tim


----------------------------------------------------------- 


Timothy J. Williams, Ph.D. 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 9359