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Re: Sinosauropteryx tail colors



> > Alternatively, the protofeathers might have had a use analogous to the
> > fur of tarantulas, or the super wispy skin of some gecko species; in
> > that they would tear off easily, leaving predators with a mouth full 
> > of (possibly irritating) fuzz.

> I do not think the protofeathers to be irritant because this seems to
> be just an apomorphy of certain spiders. As far as I know, no other
> sauropsid has irritant epidermal structures.

I don't know of any either, but many plants have similar surface structures, so 
spiders aren't the only things with a fuzzy coating that irritates the skin, so 
there is no reason to suggest dino's couldn't have had something similar.
It also doesn't mean they did.



--- On Thu, 1/28/10, Augusto Haro <augustoharo@gmail.com> wrote:

> From: Augusto Haro <augustoharo@gmail.com>
> Subject: Re: Sinosauropteryx tail colors
> To: pristichampsus@yahoo.com
> Cc: "Dinosaur Mailing List" <dinosaur@usc.edu>
> Date: Thursday, January 28, 2010, 9:48 AM
> 2010/1/28 Jura <pristichampsus@yahoo.com>:
> > This is purely speculative, but if it was originally
> evolved for display, then perhaps the display was that of a
> warning. Perhaps the animals used these protofeathers as a
> way to appear larger to rivals, or to potential predators.
> > Of course this would require the subsequent presence
> of (proto)feather erector muscles. Still, not entirely out
> of the question.
> 
> At least, there are muscles associated with the ventral
> scales in
> snakes, and probably to the dorsal scales of crocodylians
> which move
> the water on its back when mating, so I suppose that if
> they are also
> present also in bird feathers, they would also be
> associated with
> protofeathers.
> 
> >Alternatively, the protofeathers might have had a use
> analogous to the fur of tarantulas, or the super wispy skin
> of some gecko species; in that they would tear off easily,
> leaving predators with a mouth full of (possibly irritating)
> fuzz.
> 
> I do not think the protofeathers to be irritant because
> this seems to
> be just an apomorphy of certain spiders. As far as I know,
> no other
> sauropsid has irritant epidermal structures.
> 
> Ringed tail signaling does not seem to require
> protofeathers, because
> as said before, many non-avian sauropsids have similar
> patterns.
> Protofeathers would make the tail just a little larger, and
> then more
> obvious. The showing large issue seems as a reasonable
> adaptive
> explanation.
> 
> Because of the evidence suggesting tachymetabolism, lately
> increased
> with locomotion data, I would lean towards insulation, yet
> it is true
> that we do not have evidence for a more complete coverage
> by
> protofeathers (although independently inferred
> tachymetabolism would
> suggest so). Anyway, new structures are originally formed
> independently of adaptive function, and they are later
> conserved if
> they are useful. And, there may be more than one reason for
> which a
> feature like protofeathers was useful, and in such a case,
> both
> advantages increased the fitness of the animal bearing
> them. It may be
> hard to tell what one was more important if we do not have
> means of
> rejecting one of the two alternatives.
> 
> Of course, they may have been preadaptive if they were not
> so
> necessary for heat conservation (are there uninsulated
> tachymetabolic
> animals of this size?) or if the animals did not payed
> attention to
> the hair for display (do crocodiles pay attention to the
> scales of
> their fellows, or just to the the way they move the water?
> - if not,
> the EPB is ambiguous and does not give positive support to
> the display
> hypothesis).
>