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Re: Senter 2006, Confuciusornis, and humeral mobility



> Jaime Headden <qi_leong@hotmail.com> wrote:

>>   *Confuciusornis sanctus* has ... reduced form of the
>> second, major digit

The second digit is hypertrophied, not reduced. Only the ungual is
smaller. The diameters of metacarpal II and Phalanx 1 II are much greater
than those of digit III. The trochleae are large and well developed (Fig
39 Chiappe et al. 1999. Specimen GMV-2132).

I agree that the deltopectoral crest may have functioned in tree climbing
with the hands but, of course, this is not mutually exclusive with flight
stroke functions. My hypothesis is that the huge deltopectoral crest could
have functioned to give the deep pectoralis muscles greater leverage in
rotating the humeral trochlea dorsally for a powered flight stroke.

Jason Brougham
Senior Principal Preparator
Department of Exhibition
American Museum of Natural History
81st Street at Central Park West
212 496 3544
jaseb@amnh.org