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RE: (extinction)

John Bois wrote:

> At issue are two extinctions, local marsupials and enantiornithines.  
> Both of these clades are a big problem for the bolide 
> inasmuch as neither presents a reason why they were targeted and not 
> their ecological equivalents, placentals and neornithines respectively.
> And so, the bolide is forced to propose mechanisms which I find
> very far-fetched: e.g., a hermetical seal seperating enantiornithines in
> the North and neornithines in the south.

Deja vu all over again.

I object to the term 'targeted' - as if marsupials and neornithines were
prancing around with bulls-eyes on their backs.  "Look, there's one!" cries
a flying fragment of bolide.

In other words, differential survival does not necessarily imply any
selective targeting mechanism.

And tell me, 'cause I really want to know: How you *know* that neornithines
and placentals everywhere were unaffected by the impact?  Perhaps
neornithine and enantiornithine populations both plummeted at the end of the
Cretaceous, but enough neornithines survived to carry the clade into the
Paleocene (and beyond).  All you need is a dozen pairs of randy chickadees
to get the ball rolling again.

> But, as you know, exactly who were the bird survivors of the K/T is 
> still a hot topic. 

Asked and answered.  The neornithines survived.  I can't see how this is at
all controversial.