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Re: The "Swipe" of Cats [was Re: bauplan convergence]



Betty Cunningham wrote:
> 
> Monkeys and lemurs are also capable of the motion of flapping and can do
> it as well if not better than jaguars, and they both do quite a bit of
> leaping about in trees.  Hoever neither extant monkeys, lemurs, or
> jaguars have a terribly useful drag mechanism.

Most primates tend to get around by brachiating. I would think a skin
membrane attached to the arms would impede their movement. Cats, on the
other hand, spend as much time on the ground as in the trees (even more
so for the larger varieties). Mobility is also important to then,
especially since they tend to catch prey using their forelimbs.

Most creatures with skin membranes tend to have more-or-less sprawling
gaits, and spend less time on the ground than in the trees. Hence
mobility can be sacrificed somewhat, since sprawling limbs that wrap
around trunks and branches tend (at least in my opinion) to require less
mobility than a fully upright creature would (such as something that
spends a lot of time on the ground, or needs to reach up to feed or
brachiate).

Birds of course seem to be a unique case, since they don't rely on a
continuous membrane but rather a specialised composite one made up of
intricately interconnecting units (what some prefer to call "feathers").
I don't think the evolution of flight in non-feathered flyers or gliders
will tell us anything useful about the development of avian flight.

-- 
____________________________________________
        Dann Pigdon
        GIS Archaeologist
        Melbourne, Australia

        Australian Dinosaurs:
        http://home.alphalink.com.au/~dannj
        http://www.geocities.com/dannj.geo
____________________________________________