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

[Erik Boehm <erikboehm07@yahoo.com>]

> the use of the proto-wings to help capture insects has been proposed 
> before, but not being used to provide a Bernoulli Effect suction, but to 
> wave the bugs towards the mouth.

See, I never bought the "insect trap" hypothesis, and I'm not sure I'd buy the 
wave a bug into the mouth (same thing?) hypothesis. Aside from a lack of living 
examples doing such (if I am wrong, please correct me), but for an insect trap- 
I would expect the feathers to form more of a mesh with macroscopic holes, than 
a surface impermeable to air. There is a reason fly swatters have holes - 
moving a solid flat surface at a bug is likely to blow it away. Likewise it is 
hard to pick something up floating on the surface of water, when you hand comes 
up underneath it- it always seems to flow out to the side.

This is pure speculation, but a low aspect ratio wing, held against another, 
rapidly seperated, should suck air inwards towards the animal's head, while at 
the same time propelling the animal forward.

I can imagine some sort of therepod sneaking up on a resting fly or such, head 
viewing its prey between two short fat wings held in front, suddenly lunging 
forward at the insect as it beats its wings backward and pushes with its legs, 
as the insect is blown by the inrushing air towards the extending head of the 
therepod that eats it.

^^^ Pure speculation, speculation as to a possible feeding style for a therepod 
that lead to archie, no fossil evidence to support such a scheme over any 
other, but it sounds more plausible to me than some "insect trap", and a 
mechanism similar in principle is observed in fish.

It gives "half a wing" some use before it can fly or glide, but then one must 
ask what good "a fourth of a wing" does - how would the above speculative 
feeding streategy evolve, considering the predecessor likely involves briging 
the arms forward, not backward to catch prey.

The "parachuting/gliding" hypothesis has no such problems - for small animals 
than may fall from high places, longer proto-feathers means more surface area, 
and a slower fall, allowing falls from greater and greater heights - there are 
many many examples of this- from snakes that flatten their bellies, webbed tree 
frogs, coluguos (flying "lemurs") - but all are arboreal and it has never been 
shown to lead to flight (although little is known about bat evolution, and bats 
are sometimes said to group closest to primates, and may have evolved from 
arboreal ancestors.)

Vertebrate evolution of flight is rare - 3 instances- bats -> probably an 
arboreal ancestor
Pterosaurs ???? later pterosaurs seems ill suited for running to acheive fligt- 
being quadrupeds and all, but good at climbing (with the three claws - even 
more capable than bats).
Were earlier ones better suited for a bipedal takeoff?

It seems to me the reason we may not have seen a lot of "ground up" flight, is 
that it requires bipedalism, which is extremely rare as the main method of 
terrestrial locomotion (sure some animals stand on two feet on occasion, some 
lizards run away on two feet, but on a regular basis- only humans and birds do 
it that I know of).
One can also readily observe birds that run before takeoff, and many birds are 
exceptional runners.

So if it is shown flight evolved from a therepod running on the ground, and not 
falling/gliding from a tree - I wouldn't be surprised.
but given the number of independant events that acheive some form of 
aerodynamic control, of arboreal origin, I wouldn't rule out an arboreal origin 
of therepod flight, just because archie couldn't perch in a tree like birds do 
today.


--- On Thu, 9/4/08, Allan Edels <edels@msn.com> wrote:

> From: Allan Edels <edels@msn.com>
> Subject: Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)
> To: ""Erik Boehm"  " <erikboehm07@yahoo.com>, "qilongia@yahoo.com " 
> <qilongia@yahoo.com>
> Cc: "dinosaur@usc.edu " <dinosaur@usc.edu>
> Date: Thursday, September 4, 2008, 4:12 PM
> Eric:
> 
> First, WAIR is Wing-Assisted Incline Running.  It
> doesn't specify what kind of incline - it could be a
> tree branch, or a rock ledge, or part of a river bank.
> 
> Secondly, your question concerning the use of the
> proto-wings to help capture insects has been proposed
> before, but not being used to provide a Bernoulli Effect
> suction, but to wave the bugs towards the mouth.  (Forgive
> me if I got this wrong, but I think John Ostrom first
> proposed it [It's been a long day, so far....]).
> 
> Hopefully, this helps,
> 
> Allan Edels
> -----Original Message-----
> Date: Thursday, September 04, 2008 6:11:45 pm
> To: qilongia@yahoo.com
> Cc: dinosaur@usc.edu
> From: Erik Boehm <erikboehm07@yahoo.com>
> Subject: Re: Campbell's even crazier than a MANIAC?
> (archeopteryx climbing)
> 
> > Humans possess pronating and supinating wrists, a
> highly
> > mobile shoulder joint that can rotate the arm about
> its axis
> > with a nearly 160 degree range of movement in three
> > dimensions, and they can, to some degree, supinate the
> > ankle.
> 
> no doubt we have climbing adaptations, but we lost others
> such as a prehensile foot and a prehensile tail. This point
> was in response to the statement made earlier:
> 
> > Archaeopteryx not only lacks those adaptations, but
> the phenotypic 
> > trend of maniraptorans is to do the exact opposite 
> 
> My point is a trend away from an ability, does not mean
> that ability is no longer used.
> 
> What is WAIR?
> 
> I'm not saying archie climbed trees, especially not
> like a squirrel - just that the absense of the adaptations
> mentioned may not be relevant.
> Furthermore, if archie or some hypothetical ancestor of
> archie did climb up something to glide, it wasn't
> neccesarily a tree, as I mentioned boulders and cliffs.
> 
> > The problem lies in several elements,
> > including the apparent "half of a wing".
> What use
> > is such a structure on the evolution towards flight?
> 
> Is holding its arms outstretched, and rapidly parting them
> to suck in a flying insect even plausible?
> We know of many examples of feeding by sucking in the fluid
> surrounding prey, when the fluid i
> 
> Why can't a similar method work with air? it would give
> "half a wing" some use, and could then easily
> become a gliding surface.
> 
> 
> --- On Thu, 9/4/08, Jaime A. Headden
> <qilongia@yahoo.com> wrote:
> 
> > From: Jaime A. Headden <qilongia@yahoo.com>
> > Subject: Re: Campbell's even crazier than a
> MANIAC? (archeopteryx climbing)
> > To: erikboehm07@yahoo.com
> > Cc: dinosaur@usc.edu
> > Date: Thursday, September 4, 2008, 2:05 PM
> > Erik Boehm wrote:
> > 
> > <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