[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Pleurocoelus question

Tom (Lipka), you answered, referring to the question of whether the
star-shaped cross-section of pulp in sauropod teeth is unique to Astrodon

"It isn't and that was my point!"

    So , Tom, I ask you: How could you possibly know it isn't, since, as you
say (to your knowledge), those of other sauropods' teeth have not been
sectioned for comparison?

    And you ask concerning the suggestion by Steve and me that teeth of
other species of sauropod having teeth that look similar or identical
externally be sectioned for comparison of internal pulp cross-section with
the same in Astrodon johnstoni:

"To what end? Externally the teeth are virtually identical thus internally,
the x-sections were made at the "exact" same points on all specimens in
question, you would still have the star-shaped x-section."

    Sorry Tom, but that seems nonsequitir. Since, as you say, no cuts for
comparison have been made, how do you know the pulp sections, "...would
still have the star-shaped x-section" [as in Astrodon johnstoni]? What is
the source of your information that sauropod teeth which seem to look pretty
much the same externally (yet are from different species) have similarly
shaped pulp cross-section?  (Can you provide a reference?)

    You then state:

"And even if there were any statistically significant differences in star
morphology, I doubt
they would be taxonomically significant."

You seem to be presuming that the cross-section would be star shaped.  Well,
it very possibly would be, but I suspect you agree that in science we must
take nothing on faith.  Yet, without faith, how can we accept your inference
as correct, in absence of experimental documentation?  I think it more
scientifically appropriate to first determine whether pulp cross sectional
differences exist, then to determine the degree and nature of any variation,
and only then try to evaluate the possible significance, if any exists.

You further say:

"It sheds no new information as to the owner of the teeth."

    How do you know this before sectioning appropriate teeth?  Wouldn't it
at least tell us whether the 'owner' had a pulp cross-section like that seen
in teeth of Astrodon johnstoni?

    And you feel:

    "Way to many to destroy (and way to few available) in the latter case.
diagnostic bones and associated rami with teeth still in them!"

    Neither Steve nor I suggested destroying any teeth. Neatly cutting a
cros-section does not destroy, but it would add to our knowledge.
Furthermore, I did not suggest removing teeth from the bone, but would
advocate analizing teeth that are found seperated from the bone.

    And, you quoted me about whether teeth other than from Astrodon
johnstoni had been sectioned: "So far as I know, no one has done that, but
Tom may know more certainly about it", and you responded:

"I am not aware of any."

    All the more reason to section some.

    You then said:

"There are not that many teeth from all localities to (IMHO) conduct a
meaningful study..."

    Go to the one of the bigger fossil shows and see the shameful number of
sauropod teeth for sale from the U.S.A. and from various places around the

    Then you suggested:

"A CT scan might be an alternative but that's a wild guess. And the expense
at procuring and scanning so many teeth, to me at least, is not
scientifically justified. - At this point in time."

    I'm unsure whether CT scans would clearly show the pulp pattern as
distinct from, say, the dentine or the enamel,  but, if it would, one could
scan a whole bunch of teeth simultaneously (if properly arrayed for the
scan).  It should not be expensive, either, because there are probably
numerous institutions who would probably donate that service.  I know one
locally that would definitely do it without charge, because they have twive
done free CT scans on dinosaur materials for me.

    Ray Stanford

    "You know my method.  It is founded upon the observance of trifles." --
Sherlock Holmes in The Boscombe Valley Mystery