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Re: Large last gasp of pterosaurs

On Wed, 21 Jan 2004, Nick Pharris wrote:

> The hostile environment is inferred
> from the presence of a
> bolide and a knowledge of the laws of physics.  Pterosaurs became extinct at
> the same time, so it is reasonable to hypothesize that the hostile environment
> (inferred on independent grounds) had something to do with it.  No circularity
> here.

But pterosaurs as a clade seem to have had a long, gradual extinction.
This implies some other cause than a single event.  If these (probably
biological) causes are sufficient to explain the majority of pterosaur
extinctions, I would say you need some direct evidence to look for some
more exotic cause.  Anyway, the laws of physics may be relatively secure,
but their application by physicists and others can be extravagant,
calculations off by orders of magnitude, etc.  The initial question here
was about terrestrial extinctions.  Respectable scientists (Phil Currie,
for e.g.) remark on a _lack_ of change in speciation across the boundary;
and other respectable scientists w/out bones to pick (as it were) say the
fossils indicate speciation not extinction (Archibald).  This is in answer
to the claim that mammal demise contributed to the mass extinction body
count.  And marsupials _may_ have been impacted by invasions and should
not be included in the body count.  How many organisms can you remove from
the body count before organisms will cease being automatically lumped in
there?  In the meantime, using two events (Q extinction and bolide mass
extinction) as evidence for each other is illogical--that is, in the
absence of a direct connection.  In other words there really may not be a
connection between pterosaur extinction and the event at the K/T boundary.