Re: Thou Shalt Not Climb!

[David Marjanovic <david.marjanovic@gmx.at>]

> Could someone be so kind as to explain to me why is it, that a
> theropod is automatically banned from the trees unless its first
> toe is reversed???

It isn't. It's just that in the absence of such adaptations we have no 
evidence that it ever _was_ in the trees.

> On that note, what about the curved phalanges in the manus of
> Archaeopteryx? Why can't these be interpreted as an indication of
> climbing?

They clearly made climbing easier than their absence would.

But they clearly didn't evolve _for_ climbing. They are ordinary theropod 
finger claws, a _retention_, not an adaptation that evolved in 
*Archaeopteryx*. Archie simply lacked selective pressure that would have led 
to the _loss_ of the curvature.

> After all, monkeys and squirrels have the same trait.

So do *Gigantoraptor* and *Allosaurus*.

> Also, the orientation of the unguals on the manus, as well as an increased 
> range of motion for the shoulder joint in basal birds and their kin, look 
> to me like something that would come in handy when climbing...

Sure. But the increased range of motion is still pathetic by comparison to 
extant climbing animals.

> And what about the pecs?

The what? Pectoral muscles?

> Why would such a scenario not be possible?

It is possible. But that's not what we're asking. We ask "is it testable" 
and "how can we test it".