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RE: Arms into wings



At 05:20 PM 3/2/99 -0500, Patrick Norton wrote:

>I guess I'm suggesting that overall function of the arm and hand as prey   
>capturing devices must have been compromised over time once selection   
>began acting to improve aerodynamic performance.  If you are running   
>after a dragonfly and flapping, you can't also be grabbing for it with   
>your hands-- at least not without breaking the flapping rhythm.

EEEEeeekk!!!  

(I didn't just read that, did I?)

The "chasing a dragonfly" model is about as dead as _Archaeopteryx_.  No one
I know of considers that a likely life habit: heck, even Ostrom was only
partly serious when proposing it.

Archie would presumably be going after more substantial game (lizards,
sphenodontians, etc.), and dromaeosaurids much more substantial game (other
dinosaurs).

More to the point, as Padian & Gauthier showed back in 1985, the predatory
strike of a eumaniraptoran forelimb uses the same basic movements in the
same sequence as the flight stroke: it would be a synchronized movement.

>The   
>process involved a fundamental shift in the function of the arms and   
>hands from prey capture to flight. The carpometacarpus was simply the   
>coup de grace.

Yes, and the carpometacarpus doesn't appear until well up in birds (after
Archie and _Confuciusornis_ split off from other birds).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661