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Re: Avian flight stroke origin
I confirm Mr. William's observations that, in Beebe's images of juvenile
hoatzin, the feet are robust, the hallux is always used to firmly grip
branches and the forelimbs are often not employed, so that the latter are
clearly supplemental to the former.
Hoatzins definitely have strong perching feet that Archaeopteryx lacked.
> Demetrios Vital <email@example.com> wrote:
>> Osteologically speaking, does a juvenile hoatzin show a greater
>> capability for grasping than most maniraptorans?
> In _Dinosaurs of the Air_, GSP certainly argues that the juvenile
> hoatzin serves as the best modern analog for how _Archaeopteryx_ might
> have climbed trees, with the hands and feet both used to "clamber
> about branches quadrupedally".
> However, it must be remembered that the pes of the hoatzin is superbly
> adapted for anisodactyl grasping, with a hallux that is large,
> reversed, and fully descended. The hoatzin is, after all, an arboreal
> bird. Additionally, hoatzin chicks have extremely large legs and feet
> in proportion to their body size.
> There is a nice illustration of a juvenile hoatzin clambering over a
> branch in Bakker's _The Dinosaur Heresies_ (p.315). It underscores
> just how important the big, grasping feet are for climbing.
> Comparisons between small Mesozoic maniraptorans and modern hoatzin
> chicks focus on the use of wing-claws in clambering, but often
> overlook the important role of the perching feet of hoatzins.
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