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From: "[log in to unmask]" <[log in to unmask]>
To: fiona beglane <[log in to unmask]>
Sent: Thu, October 22, 2009 10:35:09 PM
Subject: Re: [ZOOARCH] pathological specimens

Fiona, it took me some time to get back to you due to having to muck
around with the Facebook-like "Zooarchaeology" site that you posted the
images in. This is not your fault, but for my part, I wish there would
just be this Zooarch list and Bone Commons and nothing
else...."Zooarchaeology" is just time consuming for no discernable
benefit, and of the two things I have the least of, vis., money and time,
time is the more precious. Plus I intensely dislike all the nosy
questions, such as about my date of birth .... it's not that I'm ashamed
of my age, but this is a security issue so naturally when such questions
are asked, I always supply a false birthdate. There is simply zero basis
for trusting anyone on the Internet OTHER than a few small groups, such as
this list which is well-patrolled by Umberto and others. Why would anybody
need to know my DOB? We note that Umberto has never asked for anything of
the sort.

So the one and only reason I went through all this rigamarole with signing
up for "Zooarchaeology" was because I really wanted to see your images of
the horse teeth, and it looked like that would be the only way.

Enough of my rant. On to your question.

'Hypoplasia' is a blanket term that just means 'failure to develop' or
even 'underdevelopment'. It's an intellectual-sounding polysyllabic to
bandy about -- very popular among veterinarians or doctors when speaking
to clients whom they hope will not ask too many more questions -- but in
fact it tells you zero about what the 'dent' in the crown of the tooth
means.

What has to be kept in mind -- and that is difficult to do because what we
have before us is always the palpably three-dimensional tooth -- is that
teeth themselves are artifacts. They are 'living tissue' only because, and
only so long as, they are invested by living cells, i.e. odontoblasts and
blood cells and connective tissue cells in the pulp and so forth.

The shape of the fully-formed tooth is the result of the shape of the
dental sac/enamel organ. Where it has wrinkles, the tooth will have
wrinkles. Where it has a salient, the tooth will have a re-entrant. So the
high degree of complexity we see, for example, in the enamel pattern of
Equus vs. Pliohippus or Cormohipparion vs. Neohipparion, is merely a
reflection of what natural selection was actually working on, i.e. the
exact shape of the dental sac/enamel organ.

What we see in your tooth is the result, not of natural selection, but of
one of two events that occurred during the time when the tooth was still
unerupted and the dental sac unbroken. The two possibilities are either
(1) a blow to the jaw, with resultant trauma to the dental sac, i.e.
bruising which inhibited or cut off blood supply to one part of the sac
for a limited period of time; or (2) a drop in nutrient supply, i.e. hard
winter or spring season and/or loss of the foal's dam/milk supply (i.e.
assuming he wasn't weaned until after his first birthday, which is often
the case in the wild).

I'm inclined to think that the best choice is (2), because of the minor
nature of the lesion, which is analogous to the 'feed change rings' you
get in hoof keratin for the same reason. Also, this pathology is not at
all infrequent in the fossil record right across all horse taxa. Surely
not so many foals would get kicked in the jaw, but I could believe that
quite a few might have barely made it through their second winter.

By the way, of somewhat more interest with this tooth is the fairly high
transverse ridging. This is something I associate with the animals
receiving processed feed (i.e. hay or grain) vs. natural graze. Would this
be a possibility given the context in which the tooth was found, and do
you have more teeth from the same jaw? It would be better to see more of
the toothrow.

Hope this is helpful. -- Dr. Deb

> Hello Zooarchers,
> I have three interesting pathological specimens that I would welcome any
> comments on.  See the palaeopathology section of the zooarchaeology
> network as bone commons are having problems with attachments at the
> moment.
>
> The first is two ribs from a medium sized mammal that have become fused
> together by two large oval shapedgrowths of bone that look to me as though
> they are some form of abscess.  They measure 37.6 x 19.3mm and 38
> (not complete) x 20mm on the inner surface of the rib cage and are visible
> as a depressed area with a raised lip all the way round.
> http://zooarchaeology.ning.com/group/zoopalaeopathology/forum/topics/pathological-ribs
>
> The second is a pig mandible.  In this case a lip of bone extended on both
> the
> buccal and lingual side of the third molar to a height of  8-9mm above the
> main body of the mandible.  There was a cavity 23 x 14 x 17mm deep
> immediately behind the third molar, and the cavity for the canine tooth
> measures 23 x 18mm and extends under
> the third molar so that it is very long.
> http://zooarchaeology.ning.com/group/zoopalaeopathology/forum/topics/pig-mandible
>
> The third is a horse molar with a kinked in a concave line along
> the length of the tooth on the lingual side 35mm above the rootand a
> corresponding convex surface on the buccal side.
> http://zooarchaeology.ning.com/group/zoopalaeopathology/forum/topics/horse-tooth
>
> Any comments or suggestions on these are gratefully received.  All are
> from medieval and post-medieval contexts from an Irish urban site.
>
> All the best and thank you in advance.
>
> Fiona
>
>
>
>