Re: Hone and Benton 2007 (their second paper)

[Michael Habib <mhabib5@jhmi.edu>]

> Secondly, and to get very hypothetical, let's say we had a bird with 
> long legs, that can leap powerfully, but is incapable of a 
> ground-to-air take-off.  Let's also say that it's a rather poor flier 
> that cannot fold its wings to the same extent as modern birds.  The 
> bird in question is something like, oh I dunno, _Archaeopteryx_.  (I'm 
> not saying that Archie was incapable of a ground-to-air take-off; but 
> for the sake of argument I'll posit that it requires elevation in 
> order to achieve flight speed).  How do you think _Archaeopteryx_ 
> would take off from a tree?

It is very hypothetical, but a fun question.  I do note that is 
something of an odd hypothetical, because birds that can leap 
powerfully generally can use leaping launch.  We'll assume for the 
moment that Archie's wing stroke capabilities are so poor that it 
cannot complete the leaping launch cycle (wherein the wings take over 
at the end of the leap), or something to that effect.

In any case, Archaeopteryx could launch from a tree just like most 
living arboreal birds, except it would not stay tucked as tightly 
during launch.  That isn't a particularly problematic situation, and 
raptors (and corvids, I think) do not tuck on gravity-assisted launch 
as much as passerines.  Most living passerines (large corvids excepted, 
as well as some others) are flap-bounding flyers, so a heavily tucked 
launch makes sense for them (it ends up being like a bound).  
Archaeopteryx was neither equipped physically, nor within the optimal 
size range, for flap-bounding.  My best guess is that it would elevate 
the wings while leaving the branch, pushing off hard with the legs.  
The wings would then be depressed in an downstroke as Archie neared 
flight speed, which would only require a very brief descent.  
Archaeopteryx could then begin flapping normally, whatever that means 
for Archaeopteryx given it's deltoid-based upstroke and primitive 
shoulder.

Cheers,

--Mike H.