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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 
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