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Re: Gansus Bird-Dino Connection - Penn Press Release

That's essentially what I meant, yes.  Other good examples would actually be 
pelicaniform birds (yes, I know, the group is polyphyletic) which all have 
totipalmate feet (and thus a non-reversable hallux).  Cormorants, 
frigate-birds, and tropicbirds can (and do) all land in trees.  Frigates can 
nest in trees, actually, despite not being able to 'perch' in the technical 
sense of the word.

Galliform birds also run (via WAIR) or fly into trees, and they do not have a 
perching foot, either.  Again, I'm speaking in the technical sense of having 
the toes wrap the branch fore and aft, not the vernacular sense of 'perching' 
which implies merely standing on a branch.

That said, I also agree that most modern birds that are truly arboreal would 
have trouble being so without a true perching foot.  The original reference (if 
I remember correctly) was to Mesozoic birds, however, which could have climbed 
quadrapedally like modern hoatzins, and thus could have been arboreal with or 
without a reversed hallux.


--Mike H.

> Climbing hoatzin chicks aren't perching...at least while climbing.  
> Cassowarys are reported to occasionally scale trees, and I doubt 
> very 
> much that they perch.  If a bird is arboreal without wrapping its 
> toes 
> around the branch I assume that would be a non-perhcing bird. That 
> said, I share Tim's general opinion that modern birds would have a 
> difficult time being arboreal non-perchers.
> Scott Hartman
> Science Director
> Wyoming Dinosaur Center
> 110 Carter Ranch Rd.
> Thermopolis, WY 82443
> (800) 455-3466 ext. 230
> Cell: (307) 921-8333
> www.skeletaldrawing.com