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fossilnut

Mako Isurus oxyrinchus (desori)?

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fossilnut

Hi I would like to get an id on this beautiful tooth that I just found in NMB,SC. One side of the root is significantly longer that the other side. The blade curves "in" near the tip. In my limited experience, it looks like a short finned mako lower tooth. It is 2 1/16 in slant height. The center of the root protudes out.

What distinquishing factors will lead to an identification for this tooth? Appreciate your thoughts. Thanks

DSCN6174.JPG

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fossilnut

DSCN6175.JPG

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fossilnut

DSCN6191.JPG

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fossilnut

DSCN6195.JPG

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The Jersey Devil

Looks more like a sand tiger 

Edited by The Jersey Devil
(Because of the nutrient groove)

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sixgill pete

Looks like it could be a worn Carcharias cuspidata. The root is well worn, cusps missing 

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fossilnut
1 hour ago, The Jersey Devil said:

Looks more like a sand tiger 

Thanks to both of you for your replies. Nutrient groove is informative. Thanks for that info. Sixgill pete you helped me realize the amount of wear on this tooth. Thanks

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MarcoSr

First let me state that it is always difficult to id shark teeth from pictures.  Seeing the tooth first hand might change what follows.  That said, the tooth looks like a lower  Isurus  desori (mako) tooth to me.  I'm not really seeing a nutrient groove which I would expect to see in a sandtiger tooth.  What I'm seeing in two pictures is root damage/erosion where a lower mako tooth would have nutrient pores.  I'm also not seeing evidence of broken off cusplets in the pictures which I would also expect to see (although there is at least one fossil species of sandtigers that have anterior teeth without cusplets).  The teeth of the extant shortfin mako Isurus oxyrinchus are very similar to fossil Isurus desori teeth.  So similar that some researchers think that desori should be synonymized with oxyrinchus.  The crowns of lower anterior teeth of desori/oxyrinchus recurve.  I don't have any pictures of my lower fossil desori teeth so I'll post for comparison a picture of a lower a1 oxyrinchus tooth from one of my shortfin mako jaws and another picture of a lower oxyrinchus tooth from e-bay.

 

5ddb3ea1bf91d_Isurusoxyrinchus(MakoShortfinShark)1lowerjawa1LLabialview.thumb.jpg.14c6f2982ca992cd12806aba9184623c.jpg

 

 

image.png.aa6c3ccb63f4172d8423588ac046442c.png

 

 

Marco Sr.

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WhodamanHD

If I had found this tooth, I would have no hesitation labeling it Isurus desori

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MarcoSr
32 minutes ago, WhodamanHD said:

If I had found this tooth, I would have no hesitation labeling it Isurus desori

 

 My hesitation in the Isurus desori id is because of how close the cutting edges of the posted tooth get to the root.  Look closely at the cutting edges of the a1 I. oxyrinchus tooth in my posted picture above of my jaw.  Neither cutting edge goes close to the tooth root and one cutting edge ends a good distance from the tooth root.  I need to dig out my fossil I. desori to look at the cutting edges.

 

Marco Sr.

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shark57

I agree with Marco. I don't think this tooth ever had cusplets. I have never seen a 2 inch cuspidata. If anyone has one, I would like to see a picture of it.

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hemipristis
1 hour ago, shark57 said:

I agree with Marco. I don't think this tooth ever had cusplets. I have never seen a 2 inch cuspidata. If anyone has one, I would like to see a picture of it.

+1

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WhodamanHD
11 hours ago, MarcoSr said:

My hesitation in the Isurus desori id is because of how close the cutting edges of the posted tooth get to the root. 

Could be some variation between modern and extinct forms. Shape just screams desori to me. No prominent nutrient grove or evidence of cusps, more robust than I’d expect for a cuspidata. 

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MarcoSr
4 hours ago, WhodamanHD said:

Could be some variation between modern and extinct forms. Shape just screams desori to me. No prominent nutrient grove or evidence of cusps, more robust than I’d expect for a cuspidata. 

 

I agree.

 

Marco Sr.

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fossilnut

Thanks to everyone for your helpful responses. Especial thanks to @MarcoSr for the pictures and the descriptions for deciding.

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