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Re: The "Swipe" of Cats [was Re: bauplan convergence]
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.
It's been suggested (though this may be becoming more unlikely with
molecular testing) megabats are descended from a near-proto-primate.
Probably the proto-bat had a drag mechanism such as skin flaps on the
hands which later formed true wings. So if we introduce a drag
mechanism to your leaping lemurs we'd possibly end up with something
the chain of flapping ability plus drag mechanism plus leaping about in
trees all leading to flight does seem to be corroborated by this.
"Jaime A. Headden" wrote:
> Betty Cunningham wrote:
> <Leaping about in trees with a symmetrical drag
> mechanism (feathers or membranes) leads to gliding.
> However gliders don't flap. Cats, squirrels, lemurs,
> monkeys, lizards, snakes, and frogs don't flap
> Another reason I mentioned jaguars was that cats
> have very mobile forelimbs, like rodents, and maybe as
> mobile as primates (ignore the hands). The power
> stroke of the bird maybe be approximated by the cats,
> with the "swipe", best seen in the tripping action of
> cheetahs chasing gazelles. Unlike my previous post on
> the arm action of dromaeosaurids (and I'll get back to
> that thread, Henri, when I get off work tonight) cats
> do not limit their pronation and supination: they
> supinate their arms to swipe, and there is no
> predilection for resisting force when moving -- the
> point is to move the claws into whatever's there,
> automatic gripping takes care of the rest. Jaguars, as
> I understand, do the same with both arms when pouncing
> from above -- so do kittens and housecats, so this is
> readily observable by most of the list. This action is
> analogous to the "predatory strike" described for
> dromaeosaurids and early birds (Ostrom, 1976a,b, 1977).
> Jaime "James" A. Headden
> Dinosaurs are horrible, terrible creatures! Even the
> fluffy ones, the snuggle-up-at-night-with ones. You think
> they're fun and sweet, but watch out for that stray tail
> spike! Down, gaston, down, boy! No, not on top of Momma!
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Flying Goat Graphics
(Society of Vertebrate Paleontology member)