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RE: BFC Epiphany



Andreas Johansson wrote:


> Yes. From the very post you linked to: "it is likely that _Longisquama_ was a
> dino-bird that had diverged from the central lineage after the 
> phytodinosaurs".
>
> Whether he's changed his views on _Longisquama_ and/or Phytodinosauria
> since I do not know - I've only got his 1995 posts to go by.


It's not clear in either instance.  I've crossed swords with George on another 
mailing list, and the thing that comes across is that BCF can be made to 
support 
or refute anything, depending on the circumstances.  The trouble is that if 
evidence emerges that contradicts a detail of BCF, Olshevksy asserts that this 
detail wasn't really "fundamental" to BCF anyway.  But if evidence emerges that 
purportedly supports BCF, then Olshevsky seizes upon it to proclaim "Aha, 
more proof of BCF!"  It's a very Procrustean way to look at the fossil record.


Case in point: BCF argued that the first tyrannosaurs were tiny volant 
creatures, and that they evolved a two-fingered hand as a way of making the 
wings
more aerodynamic.  Thus, _Tyrannosaurus_ and those big-ass tyrannosaurs we are 
familiar with are secondarily flightless bipeds that evolved from 
two-fingered flyers (= the first tyranosaurs, a la BCF).  So this aspect of BCF 
makes a prediction about what traits the earliest tyrannosaurs should possess, 
including (among other things) that they should only have two fingers.  But 
when basal tyrannosaurs turned up with three fingers per hand, this was 
inconvenient to BCF.  No matter - according to Olshevsky, this detail wasn't 
"fundamental" to BCF.  With a bit of tinkering, BCF survived this assault 
intact.


On the other hand, when a certain published phylogeny recovered _Rahonavis_ as 
a flying dromaeosaurid, Olshevsky was elated at this apparent
corroboration of BCF.  More proof, etc...


Mike Taylor wrote:


> If so, I dare say he's shifted position on that idea, too.
> Again, it's not close to the soul of BCF, it's just an incidental
> detail of one particular BCF-compliant model.


It would be nice to know beforehand which particular details of BCF are "close 
to the soul" and which are simply "incidental".  This would qualify BCF as an 
hypothesis.  As it happens, the distinction between "fundamental" and 
"incidental" is only revealed by Olshevsky _ad hoc_; i.e., if a certain detail 
of BCF is 
contradicted by the evidence, this detail was "incidental"; but if it's a 
detail that's supported by the evidence, that particular detail is 
"fundamental" to BCF.  
It's all as slippery as a hagfish (and I may be quoting someone else here).


I know it seems like I'm picking on George Olshevsky (a.k.a. "DinoGeorge") - 
and I am.  But this goes to the heart and soul of science.  Hypotheses are not 
created in order to be sacred cows.  Hypotheses are made to be tested and, as 
so often happens, refuted.  That's how science advances.


Cheers


Tim
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