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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.


>  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?


>  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!"




Cheers
Tim