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Re: Giant mammal hair (was Re: DOWNY STEGOSAURS)



> From: Scott A Hartman <ottscay@uwyo.edu>
> To: Stewart, Dwight <Dwight.Stewart@VLSI.com>
> >>>AND, let us not forget that OUR nearest relatives are all much hairier
> than
> we & one (the Gorilla) can be considerably larger.    <<<
> 
> I'm trying to find the refernce, but I seem to recall one of my
> developmental biology texts mentioning that humans have more hair per
> square inch than gorillas, ours is just much finer.

I haven't seen the ref, but offhand this strains my suspension of
disbelief.  My meager hair integument wouldn't suffice to thoroughly cover
the skin on most of my body unless the hair fibers were the diameter of
porcupine quills.  Having said this, I must point out that a single hair
follicle can hold quite a number of fibers, not just the one you might
expect on the basis of the pathetic pelt of a _Homo sapiens_ specimen.  In
domestic cats, for example, most have numerous short, fine insulating base
hairs in each follicle along with the more resilient and repellent guard
hairs, although the Siamese and Burmese varieties reportedly lack the
insulating base hairs, and, consequently, have a less "fluffy" appearance
and feel.  The aberrant Sphinx cat has fur fibers, too, but it is mostly
confined to certain regions (especially the ankles and feet). 
Functionally, one might compare mammalian base fibers to avian down or
semiplume feathers or to the plumulaceous fibers at the base of body
contour feathers.  The functions of a body contour feather's pennaceous
vanes bear some comparison to the functions of guard hairs, but, of course,
there are also many differences.  (Mickey, are we still talking about
dinosaurs)?  =;^)

By the way, Philip Currie has responded to my question on the nature of the
_Sinosauropteryx_ fibers at the D.I.G. "Dino Dish" forum, and you can read
both the question and response at the Dinosaur Interplanetary Gazette web
site, which you all have bookmarked, of course.  Currie expressed his
opinion that the numerous long, thin filaments probably branch off  the
larger, hollow fibers.  He hopes to offer a more detailed description soon.
 If Currie's interpretation of the structure of these fibers is accurate,
then the morphological difference between these theropod protofeathers and
true feathers is not such a difficult intuitive leap.

-- Ralph Miller III     gbabcock@best.com