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Re: pterosaur femora sprawl
True. But no pterosaurs walked, bipedally or quadrupedally, with a
horizontal backbone. Elevate the spine at the shoulders and voila.
MPUM 6009 is still derived in many regards, so it is the most basal
You'll need to give more detail on how you are so certain that no
pterosaurs walked with a horizontal vert. column. Of course, the more
vertical stance does not greatly affect quad launch, which is how we
got into the stance issue in the first place.
re: Odd adaptation for bipedalism:
Don't forget the albatross and the hummingbird (comparatively small
Case closed? : )
Hummingbirds can barely walk; I wouldn't consider them a good example
Albatrosses have short hindlimbs, but they follow the typical avian
scaling trend in structural strength: the hindlimbs, despite being
small, are very strong. In fact, the femur of an albatross can sustain
more load than the humerus, even though the humerus is obviously the
larger element and involved in the primary mode of locomotion.
However, the hindlimbs are the primary launch module, and the forelimbs
are not. So, in fact, albatrosses vs. pterosaurs supports the quad
stance and quad launch for pterosaurs.
Michael Habib, M.S.
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181