In the world of using the chemistry of teeth to understand ancient climate, the third molar is the “gold standard.” This is because in all mammals, the third molar (m3 or M3 – the wisdom tooth in us) starts to form after weaning. We use the chemistry of the tooth to interpret diet and environment, and by using the m3, we avoid complications due to nursing.

There are other teeth that form after weaning (like adult incisors), but no one has done the systematic study to see if the chemical ‘story’ from these teeth is the same as that from the third molar.

Likewise, the systematic study of the other tooth positions that may have the ‘nursing signal’ has not been done, so no one really knows if the other teeth (like first and second molars) really can’t be used.

That’s where you come in

With complete jaws of adult mammals, it will be possible to directly test whether or not the chemical signal of other teeth in the mammal jaw are similar to that of the third molar.

Do do this, I will be taking complete jaws of mammals and dissecting out the teeth.

Modern pronghorn m3 and i1. Scale divisions are millimeters. Research question: do these yield the same isotopic values?

I’ll collect samples from all of the teeth and see if the chemistry is essentially the same for all the tooth positions. In some cases, like the the pronghorn antelope above, I’ll only work with a couple of teeth.

  • A horse jaw, dissected to show the teeth.
  • Same horse, with the tooth positions labeled

In other cases, I’ll open up the entire jaw and sample all the teeth available, like in the horse above.

You can help

I have a number of jaws in my personal collection, but not enough to make a “statistically significant” study. To ensure that any conclusions that I draw are valid, I need multiple individual animals from many different parts of the world. I can’t do all that traveling. But maybe you have!

What I need

I need complete jaws with incisors (front teeth) from all kinds of mammals. Horses and bison (and cattle) are great, as these are the most common mammals studied using geochemistry, but other large hoofed mammals like sheep would be fantastic.

Smaller mammals like rabbits are often ignores in chemical studies, but are very common in the fossil record, so rabbit or rodent jaws would be appreciated.

Very little has been done with carnivores like foxes and coyotes, but I would like to add them to the study to cover all possible alternatives to the third molar of large herbivores.

Send ’em here

If you have jaws you’re willing to part with, please send them to me with approximate information of where geographically they lived and whether or not they were wild or domesticated.

E-mail me at pennilyn (dot) higgins (at) gmail (dot) com, and I’ll send you my shipping address and we can discuss covering your shipping costs.