Re: pterosaur femora sprawl

[Mike Habib <habib@jhmi.edu>]

> > I'm not sure how you can know this (is there something I've  
> > missed?). In
> > any case, the fore(walking)limb is always longer than the hindlimb.  
> > This
> > would result in the backbone on a slope even in the shortest  
> > forelimbed
> > critters when they had their hands on the ground.
>
> True. BTW, I've reconstructed hundreds of pterosaurs, down to the  
> species and specimen. All balanced on two feet. Plus a half-dozen  
> skeletons in 3D.

It is certainly possible to make many pterosaurs balance on the  
hindlimbs (or at least to reconstruct them that way).  However, the  
quad tracks and structural evidence for quad movement (especially quad  
launch) indicates that all four limbs contacted the ground, at least  
during walking and/or take-off.

Perhaps I should ask why you expect that pterosaurs should be  
bipedal?  Essentially, it would seem that they can be poked and  
prodded into either a biped or quadruped stance; but since we don't  
have biped trackways for pterosaurs, and given that they were built to  
take off using primarily the forelimbs (not to mention that the wings  
maintained anatomy associated with also being a walking limb), I'm  
still confused as to why a bipedal stance would be preferred.  I may  
have misunderstood you (quite likely) but it would seem, from the  
above comments, that you are arguing for bipedal gaits in pterosaurs  
because they could get into a position that balanced them bipedally.   
I'm not recognizing, however, where the simple ability to balance in  
that manner translates into the most likely gait.

Cheers,

--Mike



Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280-0181
habib@jhmi.edu