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RE: Avian flight stroke origin






> Date: Fri, 12 Aug 2011 15:40:21 +1000
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Avian flight stroke origin
> 
> Ronald Orenstein <ron.orenstein@rogers.com> wrote:
> > And birds today, even terrestrial birds, enter trees for
> > other reasons than food-finding - roosting, for example, in order to stay
> > out of the way of predators. I can well imagine that a small maniraptorian
> > might spend the day on the ground, but ascend for the night as high into a
> > tree as it could get. It wouldn't have had to be as agile as a squirrel to
> > do that - it could have used bipedal leaps to get up to its roost, and,
> > perhaps, done a bit of volplaning on the way down the next morning.
> 
> 
> This must be an intuitive thing, because I find a roosting lifestyle
> difficult to imagine for these maniraptorans. The sticking point for
> me is the lack of an enlarged, fully descended or opposable hallux.
 
 Last I checked, members of the Anteater family (or the Pangolins) lack 
opposable halluxes or thumbs or any such things.  Yet they can sleep in tree 
branches.
 
Can't we extend that possibility to maniraptors?
 

> It is not until we get to confuciusornithids or _Sapeornis_ that there
> is evidence of some kind of perching pes, consistent with spending
> long intervals of time in the trees. The modern secretary bird
> (_Sagittarius serpentarius_) spends most of its time on the ground,
> but roosts and nests in trees. It has a perching pes. So small
> maniraptorans could similarly have employed the hallux for perching
> without interfering with terrestrial progression But it was not until
> long after they evolved wings that the first perching pes evolved.
> Even therizinosaurs recruited the hallux for contact with the
> substratum.
> 
> 
> 
> 
> 
> Cheers
> 
> Tim