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RE: Making Lip of It

I wouldn't be so sure that characteristics such as large canines are _not_ the 
product of natural selection. Just because the animal is of domesticated stock, 
not all aspects of siamese breeding is controlled, and deviations (such as Rex 
hair pattern or the Scottish' fold) can enter into the gene pool without 
controls, and then become spread through the pool by selective breeding. The 
mutations in body form, color, etc., can develop and spread without controls in 
domestic cats due to uncontrollable breeding. Fanciers and professional 
breeders are not the only method by which the population booms, as my American 
shorthair/Siamese mix can attest.


  Jaime A. Headden
  The Bite Stuff (site v2)

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 

> Date: Thu, 22 Sep 2011 22:17:48 -0300
> From: augustoharo@gmail.com
> To: dannj@alphalink.com.au
> CC: dinosaur@usc.edu
> Subject: Re: Making Lip of It
> 2011/9/22 Dann Pigdon <dannj@alphalink.com.au>:
> > On Thu, Sep 22nd, 2011 at 6:03 PM, David Marjanovic 
> > <david.marjanovic@gmx.at> wrote:
> >
> > Some siamese cats develop super-occluded upper canines that permanently 
> > protrude below the
> > lips. I don't know whether it causes them any problems. It certainly makes 
> > them look creepy.
> >
> > Sabretoothed cats certainly seem to have coped with permanently exposed 
> > canines. As do extant
> > male musk deer. Naked mole rats have forgone lips altogether - although 
> > their burrows probably
> > maintain a constant level of humidity, and their teeth grow and are worn 
> > down at a much greater
> > rate than for most mammals.
> >
> You seem to be right with sabertoothed cats and musk deer, but siamese
> cats would have not bearing on the need for survival of lips covering
> teeth as they were not produced by natural selection.
> Besides, I think that another (rather weak, I admit) argument to say
> lizard-like lips were not present in non-avian dinosaurs (accepting
> their function is to keep teeth wet) may be that carnivorous dinosaurs
> and some archosauriforms have teeth generally longer than most
> carnivorous squamates. Thus, the lip should be generaly longer than in
> a lizard. For the dinosaur to bite something, and the long teeth to
> enter deeply into the flesh, the lip should be raised. This required
> to raise a bigger lip, which would require more lip musculature.
> Perhaps mammals can accomplish raising bigger lips which commonly
> protect longer canines because the larger amount of voluntary muscle
> present. Lizard teeth are commonly so short (or, when long as in
> snakes and monitors, so caudally pointing) that perhaps the lip has
> not to be raised too much more than passively for the teeth to mostly
> penetrate prey.