Onslow Strange Tusk-Like Fossil And Possible Mamman Tooth?

[Daryl McEwen]

I have a 5"+ tusk fragment or cylindrical fossil with concentric ring patterns and nice coloration not unlike another fossil found at this site by Ozzyrules. Its extremely dense and has a glossy smooth exterior.

Another head scratcher is a tooth fragment which has mammal molaresque patterns and shape.

[Sharks of SC]

I would say the first thing is a rib, rather than tusk. The tooth is pretty worn - Im not sure?

Edited February 15, 2010 by Sharks of SC

[edd]

Yeah...the first fossil is a rib of some animal and the second maybe a horse tooth, not sure

Edited February 15, 2010 by edd

[32fordboy]

The tooth looks like mammoth to me. They tend to look that way toward the ends.

Edited February 15, 2010 by 32fordboy

[Shellseeker]

I can think of nothing that has that telltale bluish enamel except for mammoth. Maybe a spit tooth because it looks more than a fragment

[Boesse]

The morphology of the spongy end of the tusklike specimen resembles the dentine "core" of the tusk of a juvenile walrus; fossil walrus tusks (e.g. Ontocetus emmonsi from the Pliocene of the east coast) is known by a few examples like this. bobby

[Daryl McEwen]

The morphology of the spongy end of the tusklike specimen resembles the dentine "core" of the tusk of a juvenile walrus; fossil walrus tusks (e.g. Ontocetus emmonsi from the Pliocene of the east coast) is known by a few examples like this. bobby

a walrus tusk would be a really interesting find. The inside of this fossil is super solid dense with no evidence of pores or nutrient ports anywhere or else I'd consider the possibility of it being rib or bone of any other kind. The shape definitely matches a rib-end but not the texture. The concentric rings are clear and go all the way to the outer edge in very fine thickness. Thanks for the help with the ID, it would be really cool to have this backed up as being tusk.

[Harry Pristis]

I don't think it's a walrus tusk. Tusks are flattened laterally. This appears to be a rib section, as others have guessed.

Something - perhaps microbial - has etched the end of this bone. It has no pattern that would not be pathological in life, in my opinion.

[Boesse]

Harry,

Not all odobenid tusks are laterally compressed - Odobenus has laterally compressed tuslks, *sometimes* - I've seen quite a few that have more of a circular cross section. Additionally, the Dusignathinae have tusks that are circular in cross section. In the case of Pliocene specimens... Ontocetus emmonsi has shorter tusks, some of which are laterally compressed. In any event, I wasn't referring to the entire tusk; there's a dentine column in juvenile specimens that occurs in the pulp cavity, which has a very distinctive morphology, and is more or less identical to the spongy end of that element. Several specimens retaining this part of the tusk were figured and described by Kohno and Ray 2008; consult that paper for further information.

Kohno, N. and Ray, C. E. 2008. Pliocene walruses from the Yorktown Formation of Virginia and North Carolina, and a systematic revision of the North Atlantic Pliocene walruses. In Clayton E. Ray, David J. Bohaska, Irina A. Koretsky, Lauck W. Ward, and Lawrence G. Barnes (Eds.), Geology and Paleontology of the Lee Creek Mine, North Carolina, IV. Virginia Museum of Natural History in Association with the Smithsonian Institution Special Publication, 14: 39-80.

[Cole]

Cool find I think. I envy your knowledge Boesse. Good stuff.

Cole~

[Harry Pristis]

Harry,

Not all odobenid tusks are laterally compressed - Odobenus has laterally compressed tuslks, *sometimes* - I've seen quite a few that have more of a circular cross section. Additionally, the Dusignathinae have tusks that are circular in cross section. In the case of Pliocene specimens... Ontocetus emmonsi has shorter tusks, some of which are laterally compressed. In any event, I wasn't referring to the entire tusk; there's a dentine column in juvenile specimens that occurs in the pulp cavity, which has a very distinctive morphology, and is more or less identical to the spongy end of that element. Several specimens retaining this part of the tusk were figured and described by Kohno and Ray 2008; consult that paper for further information.

So, Bobby, you're arguing that this highly-abraded (on one end, anyway) chunk of bone is a petrified dentin column from within a rare, juvenile, Pliocene walrus tusk, right? The enamel is knocked off (or worn off) leaving the dentin behind? How probable is that?

Edited February 16, 2010 by Harry Pristis

[hoffy]

The tusk looks like a rib with worm holes. I have seen lots maybe I mean tons of Dugon/manattee ribs with rings and they are solid and incredibly dense. I would think if it were tusk it would have crosshatching. The tooth looks like a small chunk of Mammoth. nice find

[JohnJ]

Daryl, it might help if you could post some additional photos. Try uploading closely cropped, higher resolution pics of the ends (using the Forum's Browse feature to find them on your computer). I think some of the interesting speculation is based on a lack of detail in the current photos.

Something else to consider is letting everyone know the formation, or Age, it likely came from. It's hard for me to remember sometimes that 'everyone' is not familiar with my part of the world. I like finding stuff like this because it makes you think and 'dig' for answers. The bonus is getting to hear more knowledgeable members offer their thoughts.

[Guest Smilodon]

Since the photos are inconclusive - not bad, just inconclusive, I suggest we use what information is at hand.

If I knew nothing about the specimen, just by looking at its shape, I'd bet it was a partial rib of a dugong.

Quoting Daryl, "The inside of this fossil is super solid dense with no evidence of pores or nutrient ports anywhere" . That is the exact description of a dugong rib. It certainly isn't the normal description of ivory, elephant or walrus.

Daryl also says, "The concentric rings are clear and go all the way to the outer edge in very fine thickness." That is also descriptive of dugong rib - certainly not the osteodentine portion of any likely walrus tusk from the mid-Atlantic

Thus given what we know, but pending further information, I am very sure it is not walrus and fairly confident it is a really messed up partial dugong rib.

My observation and opinion only.

BTW, Occam called - he's going with dugong rib.

Edited February 16, 2010 by Smilodon

[Daryl McEwen]

I'm not entirely sure of the exact layer it came from but there were angustiden and megalodon teeth in the area but from two different color sediments; one grayish (angy also where I found this fossil) and the other material more orange and yellow (megs). Looking at a NC geological layer map I have it would be River Bend Formation, New Hanover Member, and Comfort Member layers in the area. I should mention also that I believe the majority of the area I was searching in was piled around and previously dug up by heavy digging machinery.

Here are a few more details from the tusk/rib fossil.

[JohnJ]

Good info and excellent photos, Daryl!

[Harry Pristis]

Good info and excellent photos, Daryl!

I agree with 'JohnJ' . . . good images, Daryl.

What appeared as a rugosity in the earlier images now can be seen to be a crowd of borings. Clam starts is one good possibility.

[Boesse]

So, Bobby, you're arguing that this highly-abraded (on one end, anyway) chunk of bone is a petrified dentin column from within a rare, juvenile, Pliocene walrus tusk, right? The enamel is knocked off (or worn off) leaving the dentin behind? How probable is that?

To be accurate, I'm arguing that it's a possibility - I never said taphonomic damage was unlikely. All I'm saying is that morphology such as that need not require clams, and that tusks like this resemble this morphology. That's all.

Otherwise - look at the aforementioned article, and your question about probability will be answered.

As an aside, I have a partial dusignathine tusk that has some sort of "pathology" in the root that looks similar (on a smaller scale).

[tracer]

looks like antler material to me.

[Nandomas]

What about dugong rib?

[edd]

RIB RIB RIB!

[Frank Menser]

Have to go with rib. The other one...well I have seen Mammoth and it's a possibility, but I am leaning strongly to horse.

[tracer]

here's why i'm having difficulty with the postulates to this point. the second in the last group of pictures - there appears to be quite a "flare" out on the broken-off area, and the broken area is shiny and almost concoidally-fractured in appearance. the "flared" area does not, in my mind, match the neck or tubercle area of a rib's proximal end. this, the texture of the "eroded" surface, which to me is reminiscent of the base area of an antler, and the complete lack of trabecular bone tissue in the pictures of the broken "ends" of the thing, just kinda make me not recognize this specimen as being similar bone. i also don't see any semblance of the cross-hatching of elephant ivory, nor the "granulated" core area of walrus ivory. the issue i have with it being dugong rib is that it doesn't really match sirenian rib material i've found, which does have a bit of trabecular morphology too it, although minimal at times.

[Daryl McEwen]

If it is a rib then why the growth rings and lack of porousness and marrow cavity usually associated with bone? I was wondering because it was mentioned earlier in the thread that dugong ribs will show rings and solid density but I've never heard this before. I've also never knowingly found any dugong fossils before so I'm still unfamiliar with IDing these. Also, would the uniform density be from the fossilization process? You guys have just confused me further but I still appreciate the insight.

[Daryl McEwen]

If it is a rib then why the growth rings and lack of porousness and marrow cavity usually associated with bone? I was wondering because it was mentioned earlier in the thread that dugong ribs will show rings and solid density but I've never heard this before. I've also never knowingly found any dugong fossils before so I'm still unfamiliar with IDing these. Also, would the uniform density be from the fossilization process? You guys have just confused me further but I still appreciate the insight.

ahh, Tracer just pretty much said what was on my mind but with more eloquent scientific terms and experience. Thanks, Tracer. Also found a photo online of some dugong rib fossils that look very much like what I found in Onslow County. One can find these images by goggle imaging "dugong rib fossil"

Thanks again for all the help and information everyone! I learned something but I still am wondering why dugong ribs lack the usual bone porous structure.