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Re: pterosaur femora sprawl



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