Re: Lips and Bills

["Jaime A. Headden" <qilongia@yahoo.com>]

Well, "lip" is sorta subjective in a sense. While the heavy, muscular,
fleshy lips of mammals are often referred to as "lips," as if to say no
other animal had them, this is untrue, and lips occur in a variety of
reptiles, including all snakes snakes and many lizards. The facial
contortions of many snakes and lizards familiar to many of us should
permit one to observe the ligamental and muscular "lip-bands" of these
reptiles are easily on-part with that of most mammals (not anthropoid
primates, mind, which increased and developed unique musculature -- but
most mammals almost certainly). That these "lip holes" or nutrient
foramina served as the passage of nerves and some blood vessels has been
established for some time, as they provide branches of the auxillary
maxillary or mandibular nerves; in reptiles and more primitive animals,
these remain inside the bone, ennervating the teeth in the process, and
exit the bone to end in receptor pits, most especially notable in
amphibians and crocodiles for sensory organs; however, such anatomy is
unknown in lepidosaurs (snakes and lizards), which either provide another
means of sense (Jacobson's organ or the "pits" in pit-vipers) or ennverate
the highly mobile, muscular, and ligamentous lips.

  For any to characterize "lips" as purely mammalian would be jumping the
gun, as it excuses snakes from the mix. I am loathe to read how reptiles
lack lips, while at the same time I would be watching snakes manipulating
prey with their jaws and seeing the lips expand and envelope.

  It is likely that dinosaurs had a similar ligamentous/muscular
structure, especially theropods, whereas in ornithischians, a similar
structure would be in place in lieu of cheeks (a simple elastic tissue is
neccessary, rather than the masticatory buccal muscle in mammals) and this
is even more evidenced by the concentration of foramina in many
ankylosaur, stegosaur, and ornithopod maxillae/dentaries.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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


        
                
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