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RE: Perching, climbing, roosting was Re: 11th specimen of Archaeopteryx





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> Date: Fri, 11 Nov 2011 16:02:38 +1100
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Perching, climbing, roosting was Re: 11th specimen of 
> Archaeopteryx
>
> Anthony Docimo <keenir@hotmail.com> wrote:
>
>
> > As was pointed out in this thread today (so you may not have gotten that 
> > post in your Inbox at the time I'm
> > writing this), there are tonnes of tetrapods who have become arborean with 
> > minimal-to-no changes to their
> > feet. At the top of the list: snakes. :)
>
> And as has been pointed out myself and David M. ad nauseum... the
> bauplan of non-avian dinosaurs is not amenable to an easy transition
> from an arboreal to terrestrial lifestyle (or vice versa). This sets
> non-avian dinosaurs apart from snakes, frogs, and most small mammals,
> all of which can shift from terrestrial to arboreal habits with
> relatively few refinements to the skeleton - including the feet.
>
>
> Please, no more "but snakes/frogs/rednecks can easily climb trees
> without specialized adaptations - why not dinosaurs as well?" See
> above.
 
 So dinosaurs require special pleading?
 
 We *know* a transition occurred - we have birds these days, after all.  It 
*is* possible.  *Nobody* said it was easy.
 
But some people are saying its impossible.
 
> > depends where the branch is. some trees have their first sturdy branches 
> > over a hundred feet off the ground,
> > while other trees have sturdy branches less than a foot off the ground.
>
> Then what's the point of sleeping less than a foot of ground? So the
> little theropod climbs high enough to be out of danger from
> terrestrial predators... but not so high that a fall would be
> injurious or fatal?
 
 because you're looking for prey at the junction of branches.
 
 and I was pointing out the broad diversity of branch location - not that 
protobirds always used all branches  (if they did, why didn't you ask about the 
rainforest oens a hundred feet up?)  :)
 
 
> > And if you can't fly, you have to cross the trunk to get to the crown. ask 
> > any sloth or possum.
>
> I will. I won't be surprised if the answer from the sloth or possum
> is something along the lines of: "Dude, I'm a mammal. My ancestors
> evolved in the trees. Look at my highly mobile shoulder, hip, wrist,
> ankle and wrist joints. Marvel at my flat ribcage and supple
> vertebrate column. Admire my flexible hands and feet! Climbing is a
> cinch! Don't compare me to a %&#$ dinosaur! Now, get lost before I
> urinate on you!"
 
 um, dude, why did you wait until the one time in the week when the sloth had 
to pee?  ;)
 
 seriously, it doesn't matter what the backbone or shoulder looks like.  no 
part of mammal anatomy lets you ignore the laws of physics and plant biology 
(namely that the crown is always above any trunk, so you always have to cross 
the trunk if you're crawling from the ground to the crown - it doesn't matter 
what part of Kingdom Animalia you are)

>
>
>
>
> Cheers
> Tim