Re: pterosaur femora sprawl

[Michael Habib <mhabib5@jhmi.edu>]

> WAIR (wing assisted incline running) is a nice hypothesis, but it 
> hasn't gone unchallenged.  One concern is that this feathered 
> pre-avian maniraptoran might not have sufficient musculoskeletal 
> hardware to execute WAIR - especially if a rapid upstroke is required. 
>  Young galliforms have the derived pectoral architecture of 
> neornithean birds; feathered pre-avian maniraptorans did not.  That's 
> one of the more salient features of early bird evolution (both 
> pre-avian and early avian) - the integument is strikingly similar to 
> that of modern birds, but the osteology and musculature took a long 
> time to catch up.  This is the essence of the "mosaic" morphology of 
> _Archaeopteryx_ (and relatives).  I think WAIR understates this.

Well stated.  In fact, galliforms (including juveniles) have greater 
upstroke speed and excursion than most neornithan birds.  So, 
functionally speaking, they may be further removed from the basal 
avian/maniraptoran state than most other living birds (despite being 
fairly basal phylogenetically).  Columbiform birds pose a similar 
problem (being burst launchers, as well), though the juveniles are much 
less precocial.

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