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Re: Ah ha! That's where therizinosaurs came from



What would you say is the adaptive explanation for parrots losing their
furculae?

I think there is value in determining that "19 of 67 genera of parrots
show loss or reduction of the furcula". I'm not so sure about the value of
saying "parrots lost their furculae, possibly to lighten their skeletons,
or possibly just to annoy adaptationists".









> Jason Brougham <jaseb@amnh.org> wrote:
>
>> Perhaps it is the very notion of adaptive explanations that I'm
>> skeptical
>> of. I have more faith in sober surveys of the distribution of characters
>> rather than coming up with speculative explanations for the apparent
>> pattern.
>
>
> To me, these are two sides of the same coin.  Phylogenetic analysis
> provides us with a distribution of characters.  Adaptive explanations
> can then be inferred from the given distribution of characters.  As
> one example, the transition from bipedality to quadrupedality has
> occurred several times in Dinosauria.  But the adaptive explanation
> for each individual transition may differ, depending on the clade
> concerned (sauropodomorphs, thyreophorans, ceratopsians,
> iguanodontians).  They are only "speculative" in the sense that they
> are ultimately untestable.  That doesn't make them any less rigorous,
> or any less scientific.
>
>
>> A lot of elegant adaptive explanations, ones that thousands and
>> millions of words have been written about, have been proven false by
>> later
>> evidence. The idea that dinosaurs (they didn't say non-avian then) went
>> extinct because they were cold blooded and the world got too cool for
>> them
>> is just one such doozy.
>
>
> That's science.  It doesn't really matter how many "wrong" adaptive
> explanations came before.  As more and more discoveries emerge close
> to the origin of avian flight, we can get a clearer picture of how and
> why theropods took to the air.
>
>
>
>
>
> Cheers
>
> Tim
>


Jason Brougham
Senior Principal Preparator
Department of Exhibition
American Museum of Natural History
81st Street at Central Park West
212 496 3544
jaseb@amnh.org