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Kiwi Wings (was RE: Moasaurus)



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> ELurio@aol.com
>
> In a message dated 2/13/01 3:01:08 AM, twilliams_alpha@hotmail.com writes:
>
> << >Moa posessed no wing bones (not even vestigiel ones); [...] had a
> "stringy"
> >type of feather more suited to body insulation / protection than flying;
> >laid large eggs in a ground nest;  [snip]
>
> I think the same is actually true for kiwis too. >>
>
> No it ain't. kiwis have teensy wings with two(!) claws on each.
> They sleep
> with their beaks tucked under the wings.
>
Actually, in kiwis the finger (with ulna) develops on only the medial most
metacarpal, and indeed only two metacarpals form (not three as in most
birds).  What is even more remarkable is that kiwi wings develop in two
alternative fashions: one in which the medial metacarpal is longer and has a
digit with three phalanges (an ungual and two non-unguals); the other in
which the medialmost metacarpal is shorter and the digit has only two
phalanges. (see, for example, Parker, T. J. (1891) Philos. Trans. R. Soc.
London B 182: 26-134).

By comparison with more completely digited birds (and with tetrapod hands in
general), the first form is producing a morphological metacarpal II with its
digit, and then a digitless mc III; the other form is producing a
morphological mc I with its digit, and then a digitless mc II.

Ah, the joys of frameshifts and homeoboxes...

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796