Re: Thou Shalt Not Climb!

[Dann Pigdon <dannj@alphalink.com.au>]

mariusromanus@aol.com writes: 

> So, what I'm wondering, is how did selection take place for pre-perching 
> birds that were landing in trees with zero adaptations for such?

Many modern birds alight upon objects without having 'perching' feet. Gulls 
and pelicans can certainly perch *upon* things (but don't have much of a 
grip). I suspect that webbed bird feet in general are not very 'perchy' 
(depending on exactly how you define the verb 'perch' - I can perch upon a 
stool without using my feet to grip it :) ). 

As far as early birds went, grasping feet could have been used first to grap 
prey, which later proved useful for perching upon branches. That's not to 
say that earlier non-grasping feet prevented birds from alighting on objects 
though - or that early volant predators necessarily used their raptorial 
feet to do a lot of tree perching either. 

___________________________________________________________________ 

Dann Pigdon
GIS / Archaeologist              geo cities.com/dannsdinosaurs
Melbourne, Australia             heretichides.soffiles.com
___________________________________________________________________