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

> Yes... but all these critters have (by and large) a
> quadrupedal gait, flexible wrist and ankle joints, and a
> supple spine.  In short, they're fairly well adapted to
> life in the trees (or at least climbing).  Gliding
> squirrels, for example, use gliding to commute from tree to
> tree and so bypass the ground.  So, the comparison between
> any of these animals and _Archaeopteryx_ breaks down very
> quickly.  

OTOH, these arboreal characters are exaptations in most living gliders. Flying 
squirrels are perhaps most adapted, but *Draco* and colugos really just 
expanded on a pre-existing theme.

> _Archaeopteryx_ was a biped with a fairly rigid
> backbone, and wrist and ankle joints with proscribed ranges
> of motion.

So it did not climb like a *Draco*, that much is sure. As regards the rigidity 
of the vertebral column - certainly it was rigid when bending laterally, but 
how about bending ventrally/dorsally? This is not a direction that one normally 
would expect to be relevant, but it might be relevant here. For none of the 
arboreal gliders of our time has a fairly rigid feathered tail it might use as 
a "prop-leg". (Though again, a hypothetical scansorial Archie cannot have used 
its tail as a mainstay prop, like a woodpecker, or the tail plumage would not 
have looked so neat as it does in the fossils.)

> Perching is a way of reconciling obligate bipedalism with
> arboreality.

True, but not one that works in Jurassic theropods ;-)



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