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Re: AW: Heterodontosaurid with protofeathers



Quoting "T. Michael Keesey" <keesey@gmail.com>:

> On Tue, Mar 31, 2009 at 4:01 PM, Dann Pigdon <dannj@alphalink.com.au> wrote:
> >
> > There's no reason to assume that fur evolved just once amongst
> > mammals
> 
> Given that we have direct evidence of fur in a stem-mammal (the
> _Castorocauda_ holotype, a docodont mammaliaform), there's a pretty
> good reason to assume that. (The picture *could* be more complex, but
> at this point there's no reason to *assume* so.)

Provided of course that some mammalian lineages didn't become secondarily 
hairless, then their 
descendants re-evolved integument. That might be highly unlikely though (but 
not necessarily 
impossible).

Then again, who's to say that the fur traces that have been fossilised were in 
life chemically similar 
to modern mammalian fur? All we really know is that it was physically very 
similar in appearance. 
The original chemical composition, or the genes responsible for producing it, 
could have been very 
different. 

Or it might not have been. :-)

-- 
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Dann Pigdon
GIS / Archaeologist              http://geo_cities.com/dannsdinosaurs
Melbourne, Australia             http://heretichides.soffiles.com
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