Re: Dinosaur teeth

[bh162@scn.org (Phillip Bigelow)]

>I believe at the crystalline level, some recrystallization is going on,
>but it is not terribly profound, as the histology is almost invariably
>intact, and the substance of the bone or tooth is still
>calcium hydroxyapatite

>Michael E. Williams
>Curator of Vertebrate Paleontology
>Cleveland Museum of Natural History


There is some evidence that fluoride in groundwater
may also play a role in the long-term
stability of the carbonate hydroxyapatite, particularly
for those bones that are deposited in
acidic terrestrial environments.

The best preserved fossil bones often have a very slight
enrichment of fluorine compared to living bone.
The resultant mineral in many of these bones is therefore
carbonate fluorapatite, where some substitution of
the hydroxyl groups has taken place.  This is the same
process that occurs in the bones and teeth of people who
drink fluoridated water.

But, essentially, nearly all the apatitic material
in fossil bone is still the original bone material
(and in many bones, collagen, a bone protein, is
still present!  Real dinosaur protein!).

There is currently a scientific debate on the issue
of the degree of replacment that occurs in fossil
bone (a pro-con debate was published in
a recent issue of the British journal _Palaeontology_)
(or was it in _Palaios_?).

A popularized (and short) discussion of the role of fluoride
in the fossilization process can also be found in
David Gillette's book
_Seismosaurus: The Earth Shaker_.

             <pb>


--
                 Phil Bigelow
                 bh162@scn.org