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Re: _Night Comes to the Cretaceous_




On Thu, 6 Aug 1998 Dinogeorge@aol.com wrote:

> Way back when Alvarez et al first published
> their paper, I realized they had hit on the coup de grace: whatever dinos were
> left at the end of the Cretaceous were almost certainly wiped out by that
> asteroid impact.

>From what I have read Alvarez suffers from a too facile assuredness of his
own opinions. 

The best evidence we have suggests, and you seem to agree, that non-avian
dinosaurs were becoming less diverse anyway.  As Horner says, its like the
passenger pigeon extinction: who cares what killed the last pigeon.  If
she died from a cold would anyone say passenger pigeons became extinct due
to the cold virus?

Such explanations trivialize what is an enormously complex process.
Often (usually) extinctions have many contributing causes.  As
Leigh Van Valen says, most times attributing an extinction to one cause
rather than another can be just a matter of taste.  For example, during
the making of the Panama Canal, when the flooding of hills formed hill-top
islands, several bird species became extinct.  The apparent mechanism for
this was complex.  Whether because big cats migrated off the now too-small
range, or because of reduced hunting, small carnivorous mammals underwent
a population explosion.  They preyed the birds into extinction.  What
caused the extinction?  Habitat fragmentation? Mammal predation?  A
less-than-optimal-nesting strategy?  Now, there is every reason to suspect
multiple causes at and before the K/T.  In my view, pointing at one
particular cause just because you have some evidence which _might_
correlate, is poor science.    

Lastly, the strictly circumstantial nature of the evidence is ignored
because of the perceived value of having solid evidence.  Surely, evidence
is hard to come by; but its value shouldn't increase with scarcity.
Just as the Europeans saw Inca gold and imagined an El Dorado, Alvarez
points to an iridium layer and imagines a planet of writhing dinosaurs.
Hard evidence can be as misleading as it is alluring.  A good scientist
ought to teach _that_, and resist the seduction of facile explanations.