Hi FML!  This is Elizabeth.  I am typing this in for dad because he is
having a hard time reading stuff.  If I make any goofs, its dads fault.
 
>without seeking out the scientific publications graciously suggested by
>those more erudite than I
 
Hey, its not easy being erudite, but the tens of thousands of bones I've
looked at suggests some minor OJT as well. ;-)  To be honest, in osteology,
OJT is probably as important (or more) than book larnin.'
 
>no one so far has evaluated the methodology I've employed...then relating
>that to the total chordal length of the K9, root to point and neglecting
>the K9 curvature.  The length of the K9 measured in a manner to include
>its curvature would of course be a bit longer than it chordal length, and
>would be a bit more difficult to measure.  Also since the curvature is
>minimal relative to length, I chose chord length.
 
Big Bag-O-Worms.  I can send you references on the subject, but essentially
most people don't measure the entire tooth, just the crown section because
roots are variable and plastic in their response to the environment.  For
two examples; I have a coyote skull where the crowns are normal height for
the species, but the roots are extremely short, less than a centimeter.
Another example is a domestic dog skull affected by rubber jaw syndrome.
The roots are short and porous-looking, but the crowns appear to the eye as
normal (They aren't microscopically).  It really doesn't matter if 1) you
tell people the measurement and why you made it, 2) it is or can be
comparable with other methods.  Using a standard measurements assures both.
 
>...the sharpness of the deciduous teeth is pronounced, compared to the
>sharpness of the permanent teeth. What is the reason for this difference,
>and why, at least to my way of wonderment, is this bassackwards.
 
They are sharper because 1) they are minature versions of the adult tooth,
and a tinier tooth means a sharper point, and 2) they are not needed as
long, just a few months, so if they break it does no lasting damage.  Adult
teeth are hardier because they need to last the animal's in-the-wild
lifetime, so are generally thicker and consequently duller.  Anything that
is really sharp has to have a thin edge, which means it dulls rather
quickley.  Many carivores have teeth that wear against each other, honing
them continuously, most notable the cheek teeth or carnasials which cuts the
food, not the canines.  With ferret canines; once dull or broken, thats all
you have; no resharpening.  Besides, a kit eats food brought in by mommy and
really sharp teeth are an advantage in tearing meat; an adult kills its own
food, which is by a bite to the back of the skull or top of the neck.  You
run the risk of breaking the tooth if it is sharp or needle thin.  A
stronger, duller tooth works just fine to crush the skull.
 
>Just how do teeth stay sharp?
 
They don't normally stay sharp.  The carnasials wear against each other,
keeping the cutting edges sharp, but they can eventually wear away.  In some
mammals, the canines run against each other, doing the same thing; I have
seen this in bobcats, peccaries, but not typically in mustelids.  For the
most part, teeth get duller with age, and can wear right down to the roots.
I have a bear skull that has only a couple teeth; the bear chewed using
dentine-filled exposed roots only.
 
>Are there growth buds at the very tips that possibly concetrate Ca+ ions
>and other trace minerals there so the tips exfoliate the softer bone
>cells peripherally, leaving the calcified tip cells always on the tips?
 
Nope.  When a tooth is formed, it grows from the tip downward toward the
roots.  When the root is finished, the tooth starts filling in the root
canal with cement/dentine until the pulp is only at the tip of the root.
Enamel and dentine is formed much the same way as bone, and by similar
cells.  Since teeth have no outer covering of tissue nor nutrient supply to
feed odontoblasts, once the outer surface is formed, thats all you get,
which is why I have fillings and broken teeth never mend.
 
>Lastly, the mandibular left K9 in this skull I have shows a peculiar
>growth on its very tip that resembles the cap of a typical mushroom, is
>0.75 mm long, and closely resembles morphologically, the glans penis.  It
>is bright white and contrasts sharply with the body of the K9 it appends.
 
I would have to see it myself.  It can be the result of part of the enamel
spalling off as it drys out, it could be an accessory cusp, it could be
something stuck to the tooth that dried very hard and white (like plaque) or
it could be pathological.  My sight-unseen erudite answer would be it is
probably a plaque deposit.  If it were a pathological tooth or accessory
cusp, it would almost certainly be the same color and texture, or darker.
See if it flakes off and you have your answer.  I once cleaned the teeth in
128 Rhesus monkey skulls, all covered with the stuff.  Bright white, sharp
contrast, bumpy shape all sound just like the calcareous deposits I've come
to know and love.  The tooth probably didn't get a lot of wear in life.  In
the ferrets skulls I've examined, I've notice that in USA ferrets, the cheek
teeth are worn down at a faster rate than the canines, while in wild
mustelids, the trend is equal wear, or the canines more wear.  This is
probably due to food comsumption factors only.
 
Bob C and the 20 Emasculate Mustelids (via Elizabeth)
[Posted in FML issue 2110]