DDeden Wrote:
-------------------------------------------------------
> Sorry, I've been referencing the extra large front
> claw as the perching claw, NOT the rear-facing
> claw! The rear claw was used in balancing upright
> while on the ground, in water, on branches.

So I take it you don't have any examples of a perching bird (on the large end of the size scale) that can climb with this front facing claw like a lineman?
I don't see any here:
[animals.about.com]

I'm going with KK on this one: "That big claw seems to have been used for deadlier things than perching." The rear one then, seems too small for anything on Zs, much less for balancing. After the math comes testing a hypothesis in the real world. Birds that attack from the air have perching type feet, but much stronger, same configuration as perching though.

> Scavengers are predators in other circumstances.

[natureali.org]
My bet is this buzzard, with a similar foot type (notice that long protruding front facing middle toe?), can't climb like a lineman with it.


> At least one reason for direct killing might be
> fresh blood in live prey (eg. mosquitoes are
> parasitical flying predators). Better field of
> view from above.

Yeah, but the mosquitoes don't have a foot pattern like Zs and buzzards.

> Humans pick up needle between the thumb and
> forefinger. Chimps pick up a needle between the
> forefinger and the index finger. Zs was not a
> modern bird. Modern birds perch with a rear-facing
> toe/talon. Zs did not.

You have yet to demonstrate how any bird, modern or not could climb at all with the Zs/buzzard pattern.

>
> Do you think that you can perch (for an instant
> only, due to lack of practice) by putting the big
> toes down and the other toes curved over a branch,
> and grasping? I've done it, and written my
> signature using the same grasp (barely legible but
> nonetheless). Again, with the big toes down.

I'm not sure what you mean. Olympic tumblers can balance on a beam, but I don't see how that can be called perching.

> I did not refer to Zs's perching claw as a
> pouncing claw,

You used an owl for a model, that has a perching claw and a grasping claw that does double duty, front and rear. We need an example of same in the real world that has an oversized front facing claw that can climb with it, like a lineman.

> and certainly not a slashing claw
> (as I've seen written in the literature).

Since Zs has a head and teeth like a T-rex, I'm sure it would need something substantial to hold the victim while tearing it apart with it's teeth. So yeah, maybe the claw wasn't used for slashing per se.


> I agree sparrows don't always pounce on their
> prey.
>
> Woodpeckers bore with their beaks.

But climb with feet up vertical poles with their toes.

> Linemen use a belt, freeing their hands for work
> while they are perched vertically. Zs had 4
> perching claws, 2 in back (=spurs), 2 in front
> (=belt).

The linemen I've watched place the belt around the pole before taking the first step (or spur dig in) and then with both hands flip the belt upwards as they go, using the belt to hold them from falling as they unhook with a spur for the next step. Definitely used to climb with.
[scheerslumberjackshow.com]
These guys are using a rope, but same principle. They don't have a heavy bag of tools to worry about, so a rope works for racing I guess.


> I agree that Zs may have been moving towards a
> larger body size, but not sure.

T-rex is just a model. Take a look at these creatures:
[spinops.blogspot.com]