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

Eike, I really like this analysis. If I may, I would like to add a couple of 
minor points...

--- On Sat, 9/20/08, evelyn sobielski <koreke77@yahoo.de> wrote:

> This *would not* be the way Archie would have struggled up
> a vertical early or pre-spermatophyte (-> non-branching)
> trunk say 5 ft high. 

5 ft does not seem enough of a vertical drop to stimulate the initial 
transition from a cursorial predatory biped that utilizes isolated trees for 
roosting/nest/perch-hunting to the same, only w/ an initial parachuting/gliding 
capacity. Could we change that to 5m? :D.

> Such a structure it definitely *could*
> have used as a lookout and "perch" (except it
> would really stand atop the fronds/leaves, not perch on
> branches). 

As well as a roost or nest site...

> That much we can tell - it was neither adapted to
> sprawl-limbed climbing, nor would that be terribly efficient
> to get up . A running jump and a few lunges with the hand
> claws would to the trick better.
> And a perch of that height was all it needed to give its
> flight capability a definite and massive edge. It could
> swoop dowen on prey and keep an eye out for predators. 

Works especially well in an area where trees are well-scattered, and there is 
little undergrowth.

> And
> there were no colugos and flying squirrels and tree
> kangaroos and birds and other competitors, while parachuting
> lizards and frogs would better *not* have shared a trunk
> with Archie for their own good.
> As soon as Archie was more than 3-4 ft above ground, it
> *would* have been technically able to fly for dozens,
> perhaps hundreds of meters in most cases. That we also can
> tell. A free-standing launch site also allows to make best
> use of the wind. In such a situation, Archie's flight
> ability would be most efficiently exploited. But did it
> encounter sufficient elevated spots 

Perhaps "less is more" when it comes to available perches? One could easily 
construct a plausible cartoon wherein the Arch. ancestor is a common cursorial 
sub-dominant predator in a treeless environment, and "learns" to utilize trees 
as they appear gradually (due perhaps to climate change). This reduces the 
"in-tree" inter-specific competition while in the early phases of acquiring 
flight equipment, which of course makes being in the tree more advantageous.

> and would it have found
> it easy enough to get up there?

Slow-climbing would be sufficient if a perch allowed it to utilize 
gliding/running talents. In an environment of scattered trees and little 
ground-cover, any prey wandering by would be in big trouble, and there would be 
a minimum of arboreal nest-robbers/predators.

> Perhaps it would be worthwhile to get more geologists and
> geographers interested in the topic and hear what they can
> find out about the habitat both at the micro and the macro
> scales.