JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for ZOOARCH Archives


ZOOARCH Archives

ZOOARCH Archives


ZOOARCH@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

ZOOARCH Home

ZOOARCH Home

ZOOARCH  October 2012

ZOOARCH October 2012

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: pathological cattle tooth -- molars are not replaced

From:

[log in to unmask]

Reply-To:

[log in to unmask]

Date:

Mon, 8 Oct 2012 12:47:16 -0600

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (290 lines)

To reply to both Richard and Terry concerning the terminology for teeth --
first, as to Richard's question as to 'how far back' does the correct
usage of 'molar', 'premolar', and 'deciduous' go -- the answer is that
among vertebrate paleontologists, it goes back to when the embryology of
teeth was figured out in the middle of the 19th century, so that by the
time of the publication of William King Gregory's comprehensive two-volume
"Evolution Emerging" (1951, MacMillan & Co.), he could refer to the
"Cope-Osborn theory of dental formation".

This takes us back to all the works of Henry Fairfield Osborn, which span
from about 1880 to about 1920, in which the terminology is used correctly
along with discussion of the "tritubercular theory", which allows us to
trace the identity not only of the various teeth but the cusps of the
teeth. Their work was contemporary with that of another excellent
paleontologist, William Berryman Scott, whose still-relevant textbook "A
History of Land Mammals in the Western Hemisphere" (1913, MacMillan) also
uses tooth terminology correctly. To take it the last step back, we have
the brilliant (my hero) Edward Drinker Cope, and my fellow K.U. man Samuel
Wendell Williston. Cope's prolific output came in the 1860's through
1880's, along with his famous rivalry -- the "bone wars" -- with Othniel
C. Marsh. Williston was active a little later, during the 1880's and
1890's. All of these men used the tooth terminology correctly.

Now, the correct usage of the term "molars" as meaning "teeth that are not
replaced" or "teeth that come from an alveolus that only develops one
tooth-bud" is crucial to our being able to "count" the teeth, in other
words to write the correct tooth-formula, for any mammal. The really
difficult ones are those that have reduced dentition, i.e. for example
sloths or cats, and those that have more teeth than occur in a 'normal' or
'standard' placental, i.e. more than I3, C1, P4, M3. Thus in working with
an opossum, for example, the safest thing to do is to count forward from
the last molar, because no mammal has more than 3 molar teeth, so that any
tooth that has more than one cusp that lies ahead of the 1st molar (that
is the third one counting forward from the back) but behind the canine is
likely a premolar. Of course, if we were working with a newly-discovered
species rather than a well-known one like Didelphis virginianus, we would
ideally like to get a series of juveniles in order to XRay their jaws in
order to confirm which of the alveoli contain permanent premolars
developing beneath the deciduous ones.

Likewise, it is very helpful to know that across the whole of the
Carnivora, the carnassial teeth are superior P4 over inferior M1 in the
permanent dentition. Especially in cats, where most of the molars do not
develop, this will assure correct identification of all the teeth. Of
course, again, we know this because embryological and/or XRay studies
prove which alveoli contain two tooth-buds and which contain only one.

So well-established is this understanding of tooth terminology/tooth
embryology, that for example on p. 363 of Scott's 1913 textbook there is
an illustration of the dentition of the Collared Peccary in which only
I3/3, C/C, P2/2, and M1/1 are labeled. Having done this, the rest of the
teeth do not have to be labeled.

Gregory's "Evolution Emerging" is contemporary with the old standard Vert.
Paleo. textbook, which is Alfred Sherwood Romer's "Vertebrate
Paleontology" (with the first edition in 1933, Romer continued to update
it with new editions, reflecting new finds, until the mid-1970's). His
"Vertebrate Body" that I have already cited in a previous memo in this
thread contains an excellent explication of the development of the
mammalian skull, tritubercular theory, and standard tooth terminology.

The other branch of natural science which naturally concerns itself with
this business is Mammalogy, and the best-used textbook there is the one by
Terry A. Vaughan (1972 and later editions, W.B. Saunders & Co.). There is
an excellent illustration on p. 17 of my 1972 edition showing skull parts
and tooth identities, and the discussion of tooth and cusp evolution and
identity (largely taken from Romer) spans pp. 18-21.

Now, as to Terry's query about whether we can ever hope to get human
dentists to refer to the human premolar teeth as P3/3 and P4/4, the answer
to that is no -- because human dentists are in this game for quite
different reasons than we zooarchaeologists are. There are numerous
different systems for numbering teeth (look in Ash's "Wheeler's Dental
Anatomy, Physiology, and Occlusion" 1993, W.B. Saunders if you want to see
all of them). The reason for the existence of each of these systems is to
facilitate communication between professionals working on the teeth.

In human dentistry, the widely-used Palmer system of notation first thinks
of a person's head facing toward the dentist. Then the system divides the
tooth-bearing parts of the skull into four quadrants, which are numbered
with Roman numerals, left upper I, right upper II, right lower III, left
lower IV (going clockwise around the 'muzzle'). It then numbers the teeth
beginning with the central incisors, 1 through 8 (or more). For example,
the maxillary right first molar is designated II-6 (or sometimes just
"6").

Analogous to this we have the Williams system of notation in equine
dentistry, which works the same way. By this system, a horse's right
superior canine tooth is called II-4, its right inferior 2nd premolar
III-6, and its left superior 2nd molar is I-10.

Both of these systems completely ignore what we know about the evolution
and embryology of teeth, and thus completely obscure it. I find that many
equine dentists indeed know very little about how teeth got to be where
they are or how they came to have the form they have in whatever species;
and for this reason I find much confusion among them when there is an
anomaly such as a supernumerary tooth, a dentigerous cyst (an 'ear
tooth'), or a twinned tooth. Nor have they any knowledge of cusp
nomenclature or the development of hypsodonty or lophodonty. But, you see
that it does not really have to matter to them, because their job is not
to explain teeth but to treat or extract them.

Nonetheless I do consider the system that we use, i.e. where the basic
placental tooth formula is dI1-3, dC/C, dP1-4 followed by I1-3, C/C, P1-4,
M1-3 to be superior, and I would strongly advocate its continued use at
least among mammalogists, vertebrate paleontologists, physical
anthropologists and zooarchaeologists. The reason I consider it superior
is that it does not preclude us from understanding the simpler
'functional' numbering systems used by dentists, while allowing us insight
as to how teeth develop and what might go wrong with the normal
developmental sequence.

I want to close by highlighting something that Terry mentioned, that some
wellknown, influential, and otherwise excellent teacher of physical
anthro. consistently mis-used the term 'molar', i.e. he used it in the
vernacular sense, which terms any tooth behind the canine a 'molar'
because all such teeth are (more or less) 'grinders' in humans. This is
the usage of the farmer, rancher, and countryman. As I mentioned in an
earlier memo, I have seen this error or 'sloppy language' from some
others, particularly in equine dentistry. Vernacular usage is not wrong
any more than vernacular usage of other words is 'wrong'; but it becomes
dangerous when the teacher himself does not know any better, because it
will get students who want and need a perfectly clear understanding into
trouble. One of my maxims is that "sloppy language implies muddy
thinking". Even the human dentist does not refer to the premolar teeth as
'molars' except possibly in casual conversation with a patient whom he
thinks cannot understand anything more technical. With the better-educated
patient he may go into 'unicuspids', 'bicuspids', and 'tricuspids', which
is also rather an undefined, and certainly an antique, terminology. I
think that we are best off being careful to use the terms 'premolar' and
'molar' as correctly as our forebears Cope, Marsh, Williston, Osborn, and
Romer have taught.-- Dr. Deb



> Well, since you raise the subject....
>
> I am with Deb on this one. Granted the term 'molar' has taken quite a
> range
> of meanings over the years, both technical and vernacular, and yes,
> Cornwall (who got me started in animal bones) used to talk about
> 'deciduous
> molars', but then he was always more at home with bones than with teeth.
> We
> accept that some terms that are in vernacular use may have a more
> restricted technical definition: 'soil' is a good example. Defining molars
> by their 'grinding' function has a sort of logic when applied to people
> and
> badgers, though less so when applied to horses (in which the premolars do
> just as much grinding) or cats (in which the few molars do not grind at
> all). So an ontogenic definition, by which premolars have a deciduous
> precursor and molars *sensu stricto* are only present in the permanent
> dentition, seems to me to make an important distinction and to be worth
> maintaining.
>
> And while we are at it, can we persuade our human osteo colleagues (and
> dentists) to stop referring to the human premolars as 'first/second
> premolars'? We Old World primates have only 3rd and 4th premolars in each
> quarter-jaw, having got rid of the 1st and 2nd long, long ago in an
> evolutionary clade far away. Even the prosimians lack a 1st premolar, and
> I
> like to think that I am somewhat derived relative to an Eocene notharctine
> primate.
>
> So what do you think are our chances or getting consistent dental
> terminology into physical anthropology?
>
> Terry
>
>
> Terry O'Connor
> Professor of Archaeological Science
> Department of Archaeology, University of York
> Biology S Block, Heslington,
> York YO10 5DD
> +44-1943-328619
> http://www.york.ac.uk/archaeology/staff/academic-staff/terry-oconnor/
>
> And see the blog at
> http://zooarchatyork.wordpress.com/author/zooarchatyork/
>
>
>
> On 6 October 2012 08:07, <[log in to unmask]> wrote:
>
>> Ahh, well, Richard, it's gallant of you but of course you don't have to
>> come to the defense of anyone, because no one has been attacked.
>>
>> I probably did fail to make myself clear, however. The tooth in question
>> was a human second lower molar or m2. In my conversation with the
>> 'confused' person, I was not speaking from some old-fashioned theory of
>> the evolutionary origin of that tooth, or any tooth, but merely stating
>> the correct fact that this tooth is one of two in each rear quarter of
>> the
>> human jawbone that are not replaced. It therefore can in no sense be
>> "deciduous". To repeat: there is no such thing as a "deciduous molar";
>> it
>> is impossible by definition, because the only deciduous teeth are by
>> definition premolar, canine, or incisor teeth. That the tooth in
>> question
>> is not replaced -- in other words, it develops in and erupts from a
>> 'one-tooth alveolus' -- is what defines this tooth as a molar in the
>> technical (as opposed to the vernacular) sense.
>>
>> Your response prompted me, of course, to go back to my library to check
>> a
>> reference or two, and the happy result is that I am able to report an
>> error on p. 46 of the otherwise very helpful book "Teeth" by Simon
>> Hillson
>> (Cambridge Univ. Press). The error is in Fig. 1.25, which shows
>> deciduous
>> and permanent teeth in Homo. The error is that the labels for the lower
>> teeth have been switched -- i.e. the label that says "permanent lower"
>> actually shows the deciduous lower arcade. The labels for the deciduous
>> and permanent upper arcades are correct.
>>
>> The tooth formula given on p. 44 of this book for humans is correct:
>>
>> di2/2, dc1/1, dp2/2 ----> i2/2, c1/1, p2/2, m3/3
>>
>> ....and this is what, as I said before, I was trying to help my physical
>> anthro colleague to understand. Also as I said before: I sympathize, it
>> is
>> easy to get mixed up. -- Dr. Deb
>>
>>
>>
>> > This is off topic, but let me come to the defence of the  physical
>> > anthropologist that Deb conversed with.
>> >
>> > The anthropologist spoke of a human tooth as a 'deciduous molar'.
>> >
>> > Deb says she told the "confused" anthropologist that there are no
>> > deciduous molars.
>> >
>> > In saying this, Deb is following the evolutionary position that the
>> two
>> > human molariform teeth are adaptively evolved from premolars.
>> >
>> > I want to make the point that the physical anthropologist, in terms of
>> > nomenclature, was by no means confused. She is in step with functional
>> > terminology widely used by English speaking physical anthropologists -
>> > and dental anatomists, clinical dentists, orthodontists, etc..
>> >
>> > The two deciduous grinding teeth are called 'molars', whatever the
>> > evolutionary origin of these molariform teeth might be.
>> >
>> > Richard
>> >
>> >
>> > On 5/10/2012 05:58, [log in to unmask] wrote:
>> >> [snipped]
>> >>
>> >> I go into this a little because it's a subject dear to my own heart;
>> I
>> >> am
>> >> currently writing a textbook on equine dentistry, which I have been
>> >> researching for years. I have a great admiration for all
>> >> zooarchaeologists
>> >> but I also know, from talking with some anthro/archaeo graduates,
>> that
>> >> they can be mixed up about some things. For example recently I had to
>> >> demur (for the sake of peace) in a conversation in which someone
>> trained
>> >> in physical anthropology insisted to me that a certain human tooth
>> >> represented a 'deciduous molar'. She is confusing 'molar' in the
>> sense
>> >> of
>> >> 'cheek tooth' with 'molar' in its technical sense, i.e. molar vs.
>> >> premolar. When I told her there are no deciduous molars, that only
>> the
>> >> premolar teeth are replaced, or again that there are 'one-tooth
>> alveoli'
>> >> vs. 'two-tooth alveoli', she was surprised and confused because she
>> also
>> >> has muddled the term 'pre' in 'premolar', confusing 'pre' meaning
>> >> anterior
>> >> in TIME with 'pre' meaning anterior in POSITION. I sympathize; it is
>> >> easy
>> >> for anyone to get mixed up when the information presented in most
>> >> existing
>> >> textbooks fails to convey an adequate mental picture. -- Dr. Deb
>> >>
>> >>
>> >
>> >
>> >
>>
>

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

March 2024
February 2024
January 2024
December 2023
November 2023
October 2023
September 2023
August 2023
July 2023
June 2023
May 2023
April 2023
March 2023
February 2023
January 2023
December 2022
November 2022
October 2022
September 2022
August 2022
July 2022
June 2022
May 2022
April 2022
March 2022
February 2022
January 2022
December 2021
November 2021
October 2021
September 2021
August 2021
July 2021
June 2021
May 2021
April 2021
March 2021
February 2021
January 2021
December 2020
November 2020
October 2020
September 2020
August 2020
July 2020
June 2020
May 2020
April 2020
March 2020
February 2020
January 2020
December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
2006
2005
2004
2003
2002
2001
2000


JiscMail is a Jisc service.

View our service policies at https://www.jiscmail.ac.uk/policyandsecurity/ and Jisc's privacy policy at https://www.jisc.ac.uk/website/privacy-notice

For help and support help@jisc.ac.uk

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager