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Re: Origin of flight



Other than the acronym, I doubt if any particular element of the below is 
novel. I also doubt
if all the elements have previously been combined into 2 paragraphs. Apologies
in advance to any who deserve, or feel they deserve, citation for any particular
one element, or the whole.

The exploit of vertical-leaping-at-overhead-prey (hereafter VLOP, just because 
my fingers hurt) can be
the basis of a very appealing evolutionary scenario(s) for several reasons. If
you are small and predacious, all you really need to get started is a
population of plants of appropriate height(s), a minimum of talent, and a
supply of insects (or some nutritious substitute). Therefore, generous habitat
space, in a wide variety of climates, provides a multitude of habitats that can
sustain large and diverse populations of 'candidate' organisms for
mutation/selection to work upon. No need for more narrowly defined environments
(e.g., such as those that contain convenient inclines), behaviors, or
morphologies. Further, no matter how well you can jump, there is always a leaf
just out of reach, perhaps complete w/ a juicy bug. Therefore, any improvement
in vertical reach is likely to be rewarded, as is also the case with any
increase in the prey-capture ability of the forelimbs. Thus, VLOP is a 
convenient
scenario for transforming a quadruped into a biped, or a terrestrial biped into 
a volant one.

Further, within VLOP; proto-wings don’t need to contribute to leaping height to 
convey
advantage in the earliest stages of evolving a capacity for creating an
aerodynamic effect; any increase in hang-time and/or maneuverability (a lower
threshold of performance than generating vertical lift) increases the
likelihood of a successful prey-capture exploit. Very small increments of 
aerodynamic
effect are therefore likely to convey advantage by incrementally enlarging the
window of possible prey capture, time-wise and space-wise, making the 
morphological transition
from zero lift to non-negligible lift less troublesome. The usefulness of
wing-like structures in accomplishing sub-exploits such as swatting, or
(eventually) creating air currents to immobilize fragile and/or fleeing prey
provides prologue for the development of this minimal aerodynamic talent. 

Summing -- VLOP provides unusually fertile ground for directional selection
toward flapping flight of fortuitous feather-like structures on a biped that
has both fore-limb prey-capture, and hind-limb leaping talent. This is because 
there
is a large suitable habitat space and (presumably) a large and diverse 
population for mutation/selection to 'sample'; and the
'staging areas' of hang-time and maneuvering allow a gradual transition into
full flight mode. 

This is a (fairly standard these days?) proposed sequence
of cumulative functional advantages that could result in the modern feather,
beginning with the initial feather-like structure; thermal + camoflage ==> 
thermal +
camoflage + display ==> thermal + camoflage + display + aerodynamic effect. 

It seems to fit well w/ a VLOP-type lifestyle, and VLOP itself sequences and/or 
nests well w/in other lifestyles discussed as cradles of flight. It is a little
surprising to me that VLOP (under some other name, no doubt) hasn't received 
more attention in the "soap
opera's" mentioned below. Or did I just miss it?

Don

----- Original Message ----
From: Lucas Marti <lucasjosemarti@yahoo.com.ar>
To: nick0page@hotmail.com; paulawilder@mac.com
Cc: dinosaur@usc.edu
Sent: Wednesday, September 12, 2007 10:08:55 PM
Subject: Re: Origin of flight

Well I`ve tour leading in Brazil and seeing how pipinp guans fly from one tree 
to the other and the how they climb up the tree for another junp, and how well 
the Arboreal hypothesis fits in that image. My suggestion Nick, is you to get 
in touch with both theories and decided which one to choose (don`t read to much 
`cuase you`ll finally find that is a scientists soap opera fighting to support 
their ideas, as we, scientists, usually do, but this is a big one)

Cheers

lucas
 
Lic. Lucas Jose Marti
FCNyM. UNLP.
Tel: (54)0221-4871856
---
De: Nick Page <nick0page@hotmail.com>
Para: paulawilder@mac.com
CC: dinosaur@usc.edu
Enviado: miércoles 12 de septiembre de 2007, 4:40:44
Asunto: Re: Origin of flight


Hi Paula

TimW has made response and it looks like the idea has been around for a 
while.
It was interesting to actually observe this bird behaviour though.

Nick


>From: Paula Goodman <paulawilder@mac.com>
>To: nick0page@hotmail.com
>Subject: Re: Origin of flight
>Date: Tue, 11 Sep 2007 12:56:16 -0700
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>
>Sounds like a wonderful hypothesis to me - much better than the thing  
>about climbing trees -- did you get any responses on this?
>Paula
>
>On Sep 10, 2007, at 3:58 AM, Nick Page wrote:
>
>>A few months ago I was sitting in my garden when I noticed what I took  to 
>>be a rather dimwitted bird catching insects off the lower leaves of  a 
>>shrub.
>>
>>I am not a bird expert but it was some sort of small/medium sized  black 
>>bird.
>>
>>It was catching the insects by jumping off the ground and gaining  height 
>>into the foliage (no more than 30 cms) with a few flaps of its  wings, 
>>catching insects with its beak, and then falling rather  clumsily to the 
>>ground and disturbing the leaves as it fell.
>>
>>It kept this procedure up for about 3 or 4 minutes and seemed to catch  a 
>>lot of insects by this method.
>>
>>I then thought that a reptile with proto winglike forelimbs could do  the 
>>same job.
>>
>>The more efficient jumpers and flappers would be at an evolutionary  
>>advantage and get the most insects.
>>
>>Nick Page
>>
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