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Re: causes of K-T ferns



> Hello all,
>
> The thing that really bugs me about the volcanic derivation of the iridium
> anomaly is where are the bentonite layers that one would expect at the
> boundary?  Is there that much iridium in volcanoclastic rocks that would
> give the same signal in Montana, Italy, and other places in a layer only a
> couple centimeters thick?

Just for the record -- the Deccan traps contain 0.01 ppb iridium, which is
among the LOWEST values EVER measured. One more reason they can't be
responsible.

Can someone remind me what a bentonite is? I forgot... :-]

> lambeosaurines [...] It seems to me that they were lost due to background
> extinction.  Any thoughts?

Lambeosaurines (*Pararhabdodon*) got into Europe very late in the
Cretaceous, so I'd say they were just locally not present in the Hell Creek
because of whatever environmental factors :-/ .