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

[evelyn sobielski <koreke77@yahoo.de>]

> That of course is probably a better question, but takes us
> right back 
> to wrist and ankle morphology.  I am unaware of any
> analogous trunk 
> climbers that lack highly mobile ankles and wrists (and
> femora, for 
> that matter).  These guys all sprawl and twist their hands
> and feet 
> around to get up the substrate, which Archaeopteryx (and
> other 
> manirap...heck: theropods) could not do.

That for sure proves that *if* Archie had any sort of climbing ability, it did 
not climb the same way as e.g. a gliding squirrel or a _Draco_. But the 
"theropods couldn't" argument still needs to explain how something like 
_Microraptor_ evolved in the first place and by all accounts was quite 
successful.

The question is not "are they as well-adapted as a flying squirrel?" but rather 
"are they better-adapted than their predators and competitors?" Certainly 
better than the predators, simply for being smaller. The rest is probably 
harder to assess than it might seem. For example, was the vertebrate column 
flexible enough to allow for a sort of geometer caterpillar-like "inching" 
movement? As ungainly as that would have been, there were neither colugos nor 
flying squirrels nor any other competitor in Jurassic Europe, so "ungainly" 
might not have been "ungainly enough to prevent it". (This is not a hypothesis, 
but just a possibility that might be investigated by anyone who sees fit. 
However, a tetanuran tail with feathers could provide bracing - in which case, 
with as much certainty as such things can be said, the tail feathers would have 
been black for the most part if not completely).

BTW "crampons" - it took me some time to find out, but what I meant was 
actually tekagi. Like here 
http://shikurai.files.wordpress.com/2008/01/tekagi-5.jpg and here 
http://www.aegisteam.cz/obrazky/galerie/id120_011.jpg. They don't wedge into 
the substrate like crampons (not regularly at least) but are placed into cracks 
etc. Something any claw will do, as long as it's not too long and straight, or 
too curved. In that respect, it would be good to really shred the 
ground-up-tree-down dichotomy and look at the situation in living birds: 
woodpeckers, treecreepers, nuthatches etc vs terrestrial birds vs titmice, 
Pink-legged Graveteiro, parrots and other "acrobatic perchers".
 
> I'm not saying Archaeopteryx could never, ever get into
> a tree.  If an 
> archie found a tree (no easy chore in its particular
> environment) and 
> was highly motivated (perhaps a competition?) I'm sure
> they could 
> manage to scamper up some form of tree.  I'm just
> pointing out that 
> they lack specializations for the activity, and exhibit
> several that 
> hinder climbing,

I'll just twist this round, not because I subscribe to either view (as of now) 
but just for good measure:
"I'm not saying that Archie could never, ever take off from the ground. If it 
would an elevated area (no easy chore on a subtropical lagoon island) and was 
highly aided by circumstances (perhaps WAIRing its way up) I'm sure they could 
achieve flight. I'm just pointing out that Archie's pectoral girdle is devoid 
of anything that could have pushed its glide ratio high enough to achieve 
take-off on a regular basis from level ground."

The problem is twofold: it was not adapted enough for climbing in any way we 
can parallel in living organisms. And the ground-up scenario has always been 
hampered by aerodynamics. Archie was a good parachutist, but with little more 
ability to raise its arms than any terrestrial theropod, it would have found it 
very very hard to leave the zone of ground effect. With its leg length and 
wingspan, it is doubtful whether Archie would actually fly until out of ground 
effect, if taking off ground-up: the lift generated by simply spreading its 
wings and running would perhaps be enough to get the animal out of the ground 
effect zone, but whether it would be enough to overcome the increased drag 
above IONO.

WAIR might actually not help very much. Though their flight apparatus is very 
different, even a two-week-old partridge is probably more capable of WAIR than 
an adult Archie. It is not hard to see why WAIR research uses youngster 
Galliformes; they are among living birds those who are a) of a weakly-flying 
lineage, hence most in need of it and b) hyperprecocial and thus most capable 
of it among birds of comparable age. WAIR does not occur in other living birds 
very often or at all, and it is something that really shines when you have 
short and round wings and a sophisticaterd and powerfully-muscled pectoral 
girdle, not the other way around as in Archie.

For the moment, I prefer to remain equivocal, noting just that Archie's flight 
adaptations might have been most effective when it found an elevated spot of 
any sort, jumped, and gave a few of the half-wingstrokes it *certainly* was 
fully capable of.


Regards,

Eike

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