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Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)



My point was that a reversed toe as modern birds have, is not a pre-requisite 
for arboreal life. I did not mean to imply I think Archie probably climbed 
trees in a squirrel like manner.

I think the perching adaptation that birds have is only of use once a minimum 
proficiency in precision flight is attained, and for the first examples of 
therepod flight, the absence of a reversed toe for perching probably is 
irrelevant in the arboreal vs cursorial debate.

As many others point out - adaptations for a cursorial lifestyle do not 
preclude a partially arboreal lifestyle.

There is no denying humans gave up arboreal capabilities for cursorial ones - 
chimps climb way better than we do, but our bipedalism is a way more efficient 
way to get across open ground.

However, humans still regularly climb trees(some more than others depending on 
where one is), despite an evolutionary trend away from adaptations to do so. It 
does coincide with a dramatically decreased need or reason to climb trees 
however.

IF birds evolved from the trees down - as flight got better, I would expect to 
see tree climbing abilities getting worse, as flight would become the prefered 
method of getting up (can any bird "climb" a tree now? the most I see is 
gripping on the side of a trunck one and moving a few inches inbetween flight)
Was archie even close to being a good enough flyer that it could sacrafice any 
(hypothetical) ancestral climbing abilities? (probably not)

I still wonder about the presence of large boulders, dunes, and cliffs near 
where the first flying/gliding therepod evolved.

"Trees down" vs "ground up" may be too simple. What about "ground down", trees 
are not the only source of elevation that a gliding animal could use.

The adaptations for climbing steep or rocky terrain can be way different from 
those for climbing trees (example, a mountain goat vs a monkey)


--- On Thu, 9/4/08, dinoboygraphics@aol.com <dinoboygraphics@aol.com> wrote:

> From: dinoboygraphics@aol.com <dinoboygraphics@aol.com>
> Subject: Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)
> To: dinosaur@usc.edu
> Date: Thursday, September 4, 2008, 10:04 AM
> >>>Didn't archie have an enlarged claw as well,
> although not a true 
> "sicle claw"?
> What was the tree bark like at the time?
> squirrels climb right up the side of pine trees just fine
> without any 
> perching
> adaptations, and often jump from limb to limb, at least
> when 
> frightened.<<<
> 
> This is exactly where the analogy breaks down.  Squirrels
> have 
> laterally splayed fore and hind limbs that keep their
> cewnter of 
> gravity near the substrate, theropods (inlcuding
> Archaeopteryx) do not. 
>     Squirells have mobile ankles and wrists that allow the
> needed 
> supination/pronation during such activity, theropods
> (including 
> Archaeopteryx) do not.  Squirells have long and relatively
> flexibly 
> trunks that allow them to swivel themselves around to the
> substrate 
> during arboreal locomotion (and tree to tree leaps)
> theropods do not.
> 
> Archaeopteryx not only lacks those adaptations, but the
> phenotypic 
> trend of maniraptorans is to do the exact opposite of what
> squirrels 
> do.  They simply cannot be used as funtional analogs.
> 
> 
> Scott Hartman
> Science Director
> Wyoming Dinosaur Center
> 110 Carter Ranch Rd.
> Thermopolis, WY 82443
> (800) 455-3466 ext. 230
> Cell: (307) 921-8333
> 
> www.skeletaldrawing.com
> 
> 
> -----Original Message-----
> From: Erik Boehm <erikboehm07@yahoo.com>
> To: dinosaur@usc.edu; twilliams_alpha@hotmail.com
> Sent: Thu, 4 Sep 2008 9:43 am
> Subject: RE: Campbell's even crazier than a MANIAC?
> (archeopteryx 
> climbing)
> 
> 
> 
> > of _Archaeopteryx_ is not very well adapted to
> perching.
> > The hallux is not reversed, and it is still quite
> short and
> > high on the foot compared to later birds.  This would
> make
> > it very difficult for _Archaeopteryx_ to land on top
> of a
> > bush.  Difficult, but not impossible - but unusual if
> these
> > kind of landings were habitual.
> 
> Didn't archie have an enlarged claw as well, although
> not a true "sicle 
> claw"?
> What was the tree bark like at the time?
> squirrels climb right up the side of pine trees just fine
> without any 
> perching
> adaptations, and often jump from limb to limb, at least
> when frightened.
> 
> Perhaps a specialized perching foot like modern birds have
> wouldn't 
> come along
> until the flight prowess to make spot landings with finesse
> was there.
> 
> Many gliding species today just seem to crash into a mass
> of branches, 
> and grab
> something, on a regular basis. I think its a bad assumption
> that 
> archie's
> landings were anything resembling "pretty".
> 
> 
> Here's a question... many fish capture prey by rapidly
> opening their 
> mouths and
> sucking the prey in...
> 
> Is it plausible that some insectivore would develop a
> similar feeding 
> method,
> with air as the medium, not water?
> 
> Could something like archie have held its feathered limbs
> straight 
> forward,
> palms facing each other and in a single action rapidly
> seperate its 
> limbs -
> sucking an insect towards it, as it lunges forwardwith its
> neck and 
> head?
> 
> Does the skeletal evidence (and likely muscle attachments)
> support that
> possibility?
> 
> Has it been proposed? or are the only explanations offered
> so far for 
> "half a
> wing" (before regular flight and gliding evolved)
> "mating displays" and
> "parachutes to make falls from trees softer"
> 
> 
> --- On Wed, 9/3/08, Tim Williams
> <twilliams_alpha@hotmail.com> wrote:
> 
> > From: Tim Williams <twilliams_alpha@hotmail.com>
> > Subject: RE: Campbell's even crazier than a
> MANIAC? (archeopteryx 
> climbing)
> > To: dinosaur@usc.edu, twilliams_alpha@hotmail.com
> > Date: Wednesday, September 3, 2008, 5:21 PM
> > Scott Selberg wrote:
> >
> >
> > > It has been postulated that the hind wings of
> > Microraptor were carried below the animal and were
> used
> > to> help it steer or take tighter turns, and that
> > it's sickle claw was used to help it climb
> trees.IF it
> > turns out
> > > that Archie's environment was in fact low
> lying
> > bushes as opposed to the dense forrest environment
> > > postulated for Microraptor, it would have reduced
> hind
> > wings and a reduced sickle claw since instead of
> > > steering around trees or landing on tree trunks
> it
> > could burst ten or twelve feet into the air and land
> on
> > > top of a bush, thus reducing the need for tight
> > steering or a heavy duty crampon.
> >
> >
> > One potential problem with this scenario is that the
> foot
> > of _Archaeopteryx_ is not very well adapted to
> perching.
> > The hallux is not reversed, and it is still quite
> short and
> > high on the foot compared to later birds.  This would
> make
> > it very difficult for _Archaeopteryx_ to land on top
> of a
> > bush.  Difficult, but not impossible - but unusual if
> these
> > kind of landings were habitual.
> >
> >
> > Also, a bush would be more difficult to land on (and
> launch
> > from) than a large tree because the thin branches
> would be
> > harder to grasp than a thick and sturdy bough. 
> Especially
> > if the foot is not specialized for perching (as is the
> case
> > for _Archaeopteryx).
> >
> >
> > Cheers
> >
> > Tim
> >
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