Needs ID Possible Tusk Outer Bark Fragment.

[dbrake40]

This was found on a river gravel bar in southern Minnesota. There are glacial gravel deposits in the area. I believe it may be a piece of tusk bark (the outer bark or cementum) Thoughts?

 

Edited April 8 by dbrake40

[SawTooth]

It appears to be tusk, though it would be of great help if you had a close up from the angle of pic.#3, I believe I can see schreger lines, which are cross hatch patterns that are apparent on mammoth and mastodon ivory, but without a closer picture we can't be sure.

[dbrake40]

26 minutes ago, SawTooth said:

It appears to be tusk, though it would be of great help if you had a close up from the angle of pic.#3, I believe I can see schreger lines, which are cross hatch patterns that are apparent on mammoth and mastodon ivory, but without a closer picture we can't be sure.

The outer bark/cementum, from what I have read, does not have the characteristic Shreger lines/crosshatch.  Or are you saying it's tusk not bark?

Edited April 8 by dbrake40

[SawTooth]

What I'm saying is that it is the tusk AND the bark, the bark only being the outermost area, the slightly darker area of the outer curve, the rest of it should contain the lines.

 

(Eighth post down)

 

[dbrake40]

@Shellseeker What are your thoughts on this specimen? Note it is only about 9mm in thickness.

[Shellseeker]

I am traveling , away from my fossil collection. If home i would measure the edge , photo and expand. I thought the bands extend into the edge, but not proved it. It concerns me that there is little available on the internet about bark ivory. 

And also that we opened these same questions in 2018 without resolution.

 

[Rockwood]

Cementum is typically seen around the proximal end of teeth/tusks. If possible, a polished facet on an end may be helpful. 

[Shellseeker]

I took a look at this topic today.  I noticed a lot of things ..

1) The only people who say very much about "Bark Ivory" are on TFF or they make Bark Ivory into Knife handles and then sell the knives for an exorbitant amount of money OR they are Bark Ivory dealers and sites attempting to sell the source materials for large amounts of money compared to the costs of normal light/creamy colored Mammoth tusk ivory.  Most of my Ivory finds are in the latter category. 

2) No one outside of TFF asks any questions or discusses Schreger Bands in or out of the Bark Ivory

3)  As far as I can tell,  there are no research papers on Bark Ivory. 

4) When discussing Bark Ivory , it is the Woolly Mammoth that counts.  Columbia mammoths seem not to exist.. 

5)  There are some gorgeous pieces out there and people absolutely love "Bark Ivory"

 

Here are some statements from the sellers...

another

 

Nothing on Schreger Bands...  YET to be proved one way or the other... They all seem to be saying " if the coloration is dark and there is some texture or striations on the outer edge"  ==== BARK Ivory and pay me 3x... . 

 

 

So what do I think ?  Here is my most recent example... 

Looks like it has a dark top edge... Schreger lines are hard to detect in a whole tusk.. In a 5-8 mm slice, impossible with my camera...

Here is one off my shelf... So, lines going horizontal,  lines going verticle... Are these Schreger lines?

 

Here is something bigger that a fragment...

 

EASY for us to see and measure schreger lines... all over the place..  But see and measure the lines in the thin edge... Is that Bark Ivory  ???

 

I have tended to think Bark Ivory has a pattern that is NOT caused by fossilization OR the myas since death...  This one might qualify.  But all I find of these are fragments...

 

Final speculation... I wonder if most of what I mistake for "Bark Ivory" is actual the enamel bands from Rynchotherium. What do you think , Ken @digit ?  

 

That's all I know.. Hopefully others can add,  improve the post.... Jack

[dbrake40]

@Shellseeker - Thank you so much for the detailed answer! I also sent some photos of this to Dick Mol (Sir Mammoth) or the Netherlands. He indicated that it does seem to be a piece of the outer layer, and stated that "visible in the cross-section, is cementum and not dentin (ivory)" So to me this indicates that the outside of a tusk has cementum layers. I am going to e-mail him back and see if anyone has ever published on the topic. I think the photo you provided, below, shows these layers best. 

[Shellseeker]

11 hours ago, dbrake40 said:

@Shellseeker - Thank you so much for the detailed answer! I also sent some photos of this to Dick Mol (Sir Mammoth) or the Netherlands. He indicated that it does seem to be a piece of the outer layer, and stated that "visible in the cross-section, is cementum and not dentin (ivory)" So to me this indicates that the outside of a tusk has cementum layers. I am going to e-mail him back and see if anyone has ever published on the topic. I think the photo you provided, below, shows these layers best. 

Wow.. Thank you!  Really good answer.. Anything that backs this statement up is good to find.  Testimonials /Opinions from those who have expertise OR research papers that indicate something similar is a significant step forward... 

 

The striations or rippling on the outside surface may just be Rynchotherium examples os some residue of a unique fossilization process.  

 

Progress. I will again try to find a research paper.     Jack

[Shellseeker]

Update:  I sent an Identification Request to UF Vertebrate Research Lab and received responses from Rachel Narducci,  Director of the Vertebrate Research Lab and Richard Hulbert also commented.

 

Quote

Thanks for reaching out! I do not think that paleontologists would mention bark ivory since the bark would be cementum and the ivory would be dentine. Richard, have you heard otherwise?

 

There are schreger bands in the dentine (ivory) but not the bark (cementum). The last image that you attached does look like an enamel band of a gomphothere to me and '6487' also looks like a fragment of a gomphothere enamel band.  

I'm attaching a guide I quickly found but can do a more thorough search later.

 

Best wishes,  -Rachel

E-Ivory-guide (1).pdf

A picture from the above pdf.

 

My net:  The outside layer of a Mammoth tusk is cementum , not dentine (Ivory) and thus has no Schreger Lines.

From Richard

Quote

As far as I know, cementum on tusks is found only on the unworn "lower" half of the tusk and in appearance is similar to that found on horse teeth. I am not familiar with the term bark ivory. The cementum on a tusk is only functional on the part that is stuck in the alveoli of the skull (plus jaws for lower tusks). Once extruded beyond the bone it does not have much to do, unlike with molars, and is completely worn off the "working" end of the tusk. On fossils I have seen it is thin and brittle, and easily separates from the underlying dentine (ivory). Perhaps cementum from the portion of the tusk in the alveoli might have a rough, bark-like surface texture, that gets worn smooth once that portion of the tusk is erupted.

 

Richard

 

Net:  It is a waste of time to look for research papers on "Bark Ivory".  Scientists are barely aware of the term.  Seems like a misnomer.  If anything , it might be called "Bark Cementum"..

 

I learned something... Thanks to @dbrake40