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Re: Arms into wings

At 03:36 PM 3/2/99 -0500, Patrick Norton wrote:
><Why would it reduce prey capture? Bats use their wings to capture
>bugs-it makes a dandy scoop that funnels everything small to the mouth.>
>I'm not sure bats are a good analog, since they evolved from quadrapedal   
>insectivores whose forearms, if you look at insectivores today anyway,   


Bats almost certainly did not evolve from "insectivores" (at least in the
sense of Insectivora).  Most morphological and molecular studies place
Chiroptera within a clade (called Archonta) also containing Primates,
Dermoptera, and Scandentia (tree shrews).  That is, a clade of highly
arboreal forms.

So, don't look at the forelimbs of shrews etc. to get a glimpse at the
condition in the ancestors of bats, when those of other archontans probably
give us a much closer glimpse.

>had more to do with walking, running and climbing than killing prey.  It   
>doesn't appear that ancestors of Chiroptera would have sacrificed much   
>prey capturing ability by evolving flight. Their wings were more likely   
>exapted for that purpose after flight evolved. Cursorial dinosaurs, on   
>the other hand, lost (or at least diminished the utility of) a very   
>effective set of prey capture tools when they transformed their arms to   

Sure they did: *AFTER* they had become ornithothoracines!

However, the hands of _Archaeopteryx_ and even _Confusciusornis_ retained
quite a bit of grasping ability (as various morphometric and morphological
studies have suggested).  After all, there are few morphological differences
between the forelimbs of Archie and dromaeosaurids.

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