Re: [dinosaur] Archaeopteryx had active flapping flight ability based on wing bone geometry (free pdf)

[Tim Williams <tijawi@gmail.com>]

Ruben Safir <ruben@mrbrklyn.com> wrote:

> The most common time they use there breast muscles are on launch and it
> is unfathomable that they could launch terrestrially from the ground
> without the modern wing stroke.


You may be surprised to know that the majority of Mesozoic birds,
including most enantiornithines, did not have the full flight
apparatus of modern birds.  They are remarkably 'flat-chested'
(shallow or non-existent sternal keel), and probably lacked a
triosseal canal (so no modern-type supracoracoideus pulley).  The
deltoideus probably played a major role in the upstroke, suggesting a
flight stroke different to that of crown birds.  The modern bird-style
flight stroke is actually quite a late innovation, arising within
derived ornithuromorphs.  Are you suggesting all these basal birds
required a running take-off?  Since many of these birds (especially
sapeornithids and enantiornithines) perched in trees, this would be
quite difficult.