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RE: The Roosting Hypothesis




I think it possible in principle to rule out a ground-foraging condition in an 
individual animal on the basis of claw condition -- whether claw curvature will 
rule out ground-foraging by species remains to be seen, in my opinion.

It certainly seems attractive from a commonsense perspective -- not a silver 
bullet perhaps, but at least lead-free. 


------------------------------
On Sun, Jul 14, 2013 11:18 AM EDT Jason Brougham wrote:

>Agreed.
>________________________________________
>From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of Tim 
>Williams [tijawi@gmail.com]
>Sent: Sunday, July 14, 2013 2:51 AM
>To: dinosaur@usc.edu
>Subject: Re: The Roosting Hypothesis
>
>Lost in truncation.  Mike's response encapsulates my own opinion exactly.
>
>> From:  don ohmes <d_ohmes@yahoo.com>
>>
>> Summing -- it follows that a trees-down path to powered flight *can*
>> occur
>> in the absence of a reversed hallux or "arboreal adaptations".
>> GSP's claims re curvature will do much to define future discussions if
>> they hold up -- given the presence of sharp claws on even one fossil,
>>  I am
>> optimistic...
>
>I like the GFTR hypothesis, as Don calls it, from a thought experiment
>standpoint.  It seems to be both plausible and consistent with known
>biology.  However, to the extent that it holds true, the same list of
>observations basically confirms that we can't tell if there was
>"trees-down" component to flight origins (just as we cannot refute it).
>GFTR seems to predict, essentially, that the animals would look
>terrestrial.  The claw curvature measure might give some indication of
>more climbing, but it's not a silver bullet.  So, ultimately, we have
>three models: high arboreality, partial arboreality, and full
>terrestrially for flight origins.  The high arboreality predictions do
>not seem to hold true, so we can tentatively discard that one.  But then
>there seems no way to test between the other two, as they predict the
>same morphology.  Since there was never a particularly compelling reason
>to put these animals in the trees vs the ground to begin with, I would
>call the result a stalemate.
>
>--Mike