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Re: 11th specimen of Archaeopteryx
David Marjanovic <firstname.lastname@example.org> wrote:
> Just to make absolutely sure nobody overextends this analogy -- turkeys have
> long, reverted first toes, Archie didn't; turkeys roost in
> ordinary trees (as opposed to cycads), Archie is not likely to have done so,
> no matter how much time it may have spent in cycads.
Exactly. _Archaeopteryx_ shows no evidence in support of perching or
roosting behavior. The hallux was fairly short, fairly high, and not
reversed. Turkeys tend to forage on the ground, and so have a shorter
hallux than other galliform birds that spend more time in trees. But,
as with the peafowl (which also spends most of its waking hours on the
ground) the hallux is still plenty long enough (and fully reversed) to
be used for perching - although not on really narrow branches or twigs
Don Ohmes <email@example.com> wrote:
> It is worth mentioning that cycads and plants with similar morphology can be
> easily utilized as perches, roosts, havens and restaurants by animals whose
> lifestyle could be characterized functionally by the term 'turkey w/ teeth'
> -- I am not saying that Arch. definitely was a 'toothed turkey' in it's
> lifestyle, but it certainly seems plausible.
I concur with David M. that there is a huge amount of morphospace
between turkeys and _Archaeopteryx_ (or any basal avialan... or
whatever we're calling them now).
> Cycads often have slanting/curved trunks -- particularly when massed
> together -- and a rough, often stepwise exterior that is easily negotiated
> by small animals w/ claws. The usual rosette at the top is a form that even
> a medium size dog or boy can "perch" in -- not in comfort perhaps, but w/out
> risk of falling.
Also, cycads tend not to be branched. Another reason why a perching
pes might be not so useful. However, a pes in which all four toes are
pointed forward might be more useful...
> In fact, getting out of a cycad might be harder than getting up one -- hence
> the advantage of parachuting abilities.
Yes, I pretty much agree:
As Prof. Jeremy Rayner has pointed out time and time again, there is
no reason to assume that gliding can only evolve in an animal that is
specialized for an arboreal lifestyle.