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Re: New Papers



"Jerry D. Harris" wrote:

> 
> I think this one warrants putting the abstract here:
> 
> "Three origins for flight in birds are discuseed in terms of adaptive
> scenarios. The discovery of feathered but flightless dinosaurs in China
> suggests that many of the adaptations in birds, currently considered as
> components of flight, might better be considered as requirements for the
> success of feathers and the development of feathers may well have been a
> more important event in bird evolution than the development of flight. The
> existence of an array of potential ancestors with feathers and the success
> of large groups of birds without volant representatives suggest that flight
> might have evolved more than once."

Of course I've yet to read the article in question, but in general I
agree with what the abstract says. I think anything that had feathers
for whatever reason (display, streamlining, sulphur excretion,
brooding... pick you favourite) could have given rise to a line of
animals that developed some variety of flight. After all, no-one would
suggest that all spiny mammals (hedgehogs, porcupines, echidnas etc)
have a common spiny anscestor just because they all developed similar
structures from mammalian hair. Similarly, flight almost certainly
developed several times with insects - butterfly and moth flight is
quite different to that of beetles and the like.

I recently tried to imagine why non-flighing animals like Caudipteryx
and Protarchaeopteryx would have benefited from feathered forelimbs,
assuming they are not secondarily flightless (which is not necessarily
something I completely rule out). I really don't see the logic of waving
feathered forelimbs about while trying to run, it seems counter
productive. It occured to me that if the forelimbs were held folded
tightly against the body while in a fast run, a fan of feathers may have
helped streamline the forelimbs so that they blended into the body wall
more smoothly (smoothlier?).

Does anyone think that Caudi et al had muscular control of their tail
feathers, enabling them to spread them when needed, and to fold them
back when not? Could it be that something as small as Caudi didn't need
a specialised pygostyle-like caudal series distally, while something as
large as Nomingia would have (for the muscular control of caudal
feathers that is)?

-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS Archaeologist           http://dannsdinosaurs.terrashare.com
Melbourne, Australia        http://home.alphalink.com.au/~dannj/
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