RE: Dromornithids and size limits.

["Tim Williams" <twilliams_alpha@hotmail.com>]

Jaime A. Headden wrote:

> > However, parrots and turacos are birds that are effectively three-legged 
> > climbers, in that they use >their beaks to manipulate and clamb with.

So do young hoatzins, effectively making them five-legged climbers.

The Japanese shearwater has been observed climbing trunks with the aid of 
its wings.

Eric Martichuski wrote:

> Effectively, yes.  But are they _effective_ climbers?

Not sure they need to be, since they can fly.

> Meanwhile, while the Killer Bird has one predatory appendage, the 
> sabretooth, or other predator has _three_.  A lion leaping up to claw and 
> bite as the hindquarters of its fleeing prey has a better chance of staying 
> attached than a phorusrhacoid would with its single, albeit wickedly 
> hooked, anchor into the prey's flesh.

Phorusrhacoids and other predatory birds also use their feet as predatory 
instruments.  Quite effectively in most cases.

> I say nothing against the marvelous talents of birds.  They rule the skies 
> with an awesome diversity and fecundity.  I merely say that, having 
> specialized to such an amazing degree, they pay the price of finding it 
> more difficult to de-specialize and find something else.  They are, in a 
> sense, stuck.

In ornithothoracine birds, the forelimbs do seem "stuck" in a locomotory 
function (usually air or water).  However, the wings of the phorurhacoid 
_Titanis walleri_ may have reverted to some predatory function, but I'm not 
sure what.  Perhaps they were used as claspers for holding prey, 
tyrannosaurid-style.  Many modern birds use their wings in intraspecific 
combat, and have spurs or clubs for this purpose; these birds tend to weak 
fliers.



Tim

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