Mammoth or Mastodon tusk?

[Cwoods]

Hello, Fossil Forum users! I work at a natural history museum and have discovered a lovely tusk specimen that is sadly lacking any labeling or documentation whatsoever. No one has a clue where it came from... odds are, it's local to Western WA, but without knowing the provenance there's no way to be sure.

I'd like to at least identify it to the mammoth/mastodon level so I can put some kind of label on it. I've done some research and learned a bit about Schreger lines, but most resources I've found are more about telling the difference between elephants and mammoths/mastodons, which doesn't help me since I know it's definitely not an elephant tusk! I'm also having trouble figuring out which angles/lines are the diagnostic ones. Any help in understanding this difference would be greatly appreciated!

Here are more photos: http://imgur.com/a/8ak2R

Edited March 1, 2016 by Cwoods

[Auspex]

This would be the angle of intersect to measure:

[DPS Ammonite]

I did some research to help differentiate mammoth from mastodon tusks. The Schreger lines in almost all cases are similar between the two--the line intersection angles that are concave toward the inside of the tusk average less than 90 degrees. Most sources point out that almost all high quality commercial fossil ivory is mammoth because they tend to be better preserved in permafrost. Almost all mastodon ivory is not commercial quality carving ivory because of poorer preservation in warmer climates. Therefore if your tusk is a high quality carving ivory (I can't tell) then it is most likely a mammoth tusk.

The easiest way to ID the tusk is if you have most of the tusk. Mastodon tusks were shorter and much straighter while mammoth tusks are much more curved.

I would talk to the scientists at the George C. Page Museum at the Rancho La Brea Tar Pits in Los Angeles since both mammoths and mastodons are found there.

Good luck.

See these references:

http://www.internationalivorysociety.org/identification.html

http://skywalker.cochise.edu/wellerr/students/mammoth-mastodon/mastodon.htm

Edited March 2, 2016 by DPS Ammonite

[abyssunder]

Welcome to the Forum!

I agree with the others.

As Auspex pointed very well, those are the important Schreger angles to determine if the tusk is from a Mammoth,Mastodon or other Proboscidean. As far as I know, if the angles of the crossing Schreger lines are acute - belongs to Mammoth, if they are obtuse - belongs to Mastodon (which in reconstructions based on partial and skeletal remains were very similar in appearance to elephants). Here are some comparative measurements compiled by M.R.Palombo et al. in their works,and also other references:http://www.thefossilforum.com/index.php?/topic/59211-mastodon-bones-tusk/

Here is a comparative diagram representing data of schreger angles measured near the cementum-dentine junction in different proboscidean tusks, according to Palombo&Villa 2001 and Virag Attila; data (marked with red) of the Hungarian and Siberian proboscideans.

Dan Fisher (University of Michigan) and his colleagues have quantified a significant species difference between mammoths and mastodons in these intersection angles. Fisher found that the Schreger pattern angles of Mastodons average about 124.7 degrees, and those of Mammoths average 87.1 degrees.

Hope all this helps.

Reference: MAGYARORSZÁGI PLIOCÉN-PLEISZTOCÉN ELEPHANTIDAE
MARADVÁNYOK MORFOMETRIAI ÉS PALEOÖKOLÓGIAI VIZSGÁLATA,2013 - Virag Attila http://teo.elte.hu/minosites/ertekezes2013/virag_a.pdf

Edited March 2, 2016 by abyssunder

[Cwoods]

Auspex- thanks so much for pointing out what I should be measuring. Now I just need to hunt down a protractor!

DPS Ammonite- that background is super helpful. Can't believe I forgot to include a picture of the entire tusk! It's about a 3-ft section, so I don't think that will help. It's not in bad shape, but I really don't think it's carving quality. Thanks for the references and contacts! Here's a photo of the whole thing, in case you are curious: http://i.imgur.com/5sIi83z.jpg

abyssunder- Glad to be here! I'm so impressed at the high quality of the discussion. Thanks for the scholarly references- I didn't realize the difference in angles between the two species was that large; I'm still a bit puzzled by the variation in the angles I'm seeing on my specimen (some look obtuse, and some look acute) but on the whole they are around 90 degrees, maybe a bit less, so I suppose I've got a mammoth!

[JohnJ]

I would definitely remove it from that window sill. The constant temperature variation will not be good for its long term stability.

[Cwoods]

JohnJ, I agree so much! Perhaps it can go back in the moldy shed with our other specimens.... sigh

[abyssunder]

Nice specimen! Thanks for posting in TFF.

[DPS Ammonite]

Does anyone know if an isotopic analysis of the mammoth or mastodon's tusk (or teeth and bones of other ice age animals) can reveal where the animal was born and raised? Did the tusk come from Washington, California, Texas etc? I recall that isotopic analysis of human bones and teeth can reveal where humans (such as the "Ice Man" in the European Alps) came from.

Edited March 6, 2016 by DPS Ammonite

[wezgo]

Hello,

I did some looking around on the web and found a post ( sorry I cant remember where it was) that said that mammoth tusks have a bark while mastodon tusks do not.

I hope this helps

[abyssunder]

On 3/6/2016 at 8:45 AM, DPS Ammonite said:

Does anyone know if an isotopic analysis of the mammoth or mastodon's tusk (or teeth and bones of other ice age animals) can reveal where the animal was born and raised? Did the tusk come from Washington, California, Texas etc? I recall that isotopic analysis of human bones and teeth can reveal where humans (such as the "Ice Man" in the European Alps) came from.

 

" Stable isotopes can be of use in designating isolated proboscidean skeletal remains as mammoth or mastodon, but such designations remain tentative in the absence of morphological or molecular data. Mammoths tend to have higher δ15Ncol and lower δ13Ccol than mastodons, but the specific range of isotopic compositions differs among geographic locations and time periods, and may not be significantly different in every region. Mammoths, in particular, can have a very large range of δ15N values, as shown for specimens from Alberta. Ideally, taxonomic designations based on stable isotopes should only be attempted for specimens from known locations and time periods, where baseline (preferably non-overlapping) isotopic compositions for the taxa in question have been determined previously. (...)
Our results also demonstrate that stable isotope analysis can be helpful in assigning geographical provenance to isolated museum samples that lack collection data. Bioapatite δ13Csc and δ18Osc are most useful for determining locations of origin, and could be used to distinguish proboscideans from Alberta, Old Crow, Klondike, Herschel Island, and locations further south (e.g., Arizona and the Great Lakes). Collagen δ13C could provide a secondary line of evidence for determining the location of origin of mammoths, but δ15Ncol was not useful for this application. The isotopic data we have provided can be used as a baseline for future studies of specimens lacking provenance, and are particularly useful since the Yukon is the most prolific source of proboscidean fossils in Canada. It is highly probable that many skeletal remains without provenance in local museum collections are from Yukon, and isotopic determination of their location of origin may be possible. Furthermore, the isotopic baseline we have provided could be used to support inferences of migration, but only if climate-related variations can be ruled out.  "

 

excerpt from J. Z. Metcalfe et al. 2016. Taxonomy, location of origin, and health status of proboscideans from Western Canada investigated using stable isotope analysis. Earth Sciences Publications. Paper 8:1-53