Shark Tooth ID

[Bails]

Hey all,

 

I found this tooth this morning hunting in Charleston, SC. I was hoping someone could help me ID it. Is it Isurus desori? Or is it Isurus hastalis? That was my initial thought, but it is so much bigger, thicker, and robust than the other Isurus desori teeth I have found in Charleston, SC and most Isurus hastalis teeth I have found are more broad/wide. So figured I would run it past some folks here to make sure the ID is correct. Thanks I’m advance!!!

 

@MarcoSr @WhodamanHD @BellamyBlake @Al Dente @Praefectus

[Fossildude19]

Are the edged serrated?

 

[Bails]

@Fossildude19

 

It doesn’t have serrated edges. Thanks.

[Shellseeker]

From our TFF members Gallary

 

[Bails]

Thanks!

[bthemoose]

Wait for others, but I believe this is Isurus retroflexus. It's a gorgeous tooth!

[Bails]

Yeah I think that’s a safe bet and thanks!

[MarcoSr]

My initial impression is a retroflexus tooth.  Definitely doesn't look like I. desori to me.

 

Marco Sr. 

 

 

EDIT:  Look at tooth A in the below picture from Cappetta 2012.  Note Cappetta considers retroflexus a thresher and not a mako which is not accepted by a lot of shark researchers.

 

 

 

 

Edited November 25, 2020 by MarcoSr
added picture

[WhodamanHD]

I’m also in the retroflexus camp

[Shellseeker]

16 hours ago, MarcoSr said:

My initial impression is a retroflexus tooth.  Definitely doesn't look like I. desori to me.

 

Marco Sr. 

Quote

Mako teeth from Lee Creek are assigned by this page's authors to three 'species' — Isurus oxyrinchus and the chrono-species I. retroflexus (Miocene - Pungo River) & I. paucus (Pliocene - Yorktown Formation).

http://www.elasmo.com/frameMe.html?file=heim/leecreek/lc-isurus.html&menu=bin/menu_topics-alt.html

Most Makos I find in Florida are Isurus hastalis. Occasionally, I find an odd looking Mako that seem not to be. I could not say positively what they are. Is it easy or difficult to differentiate between species of Mako? There seems to be an attempt at unique characteristics in the elasmo thread above.

 

 

 

 

[MarcoSr]

2 hours ago, Shellseeker said:

http://www.elasmo.com/frameMe.html?file=heim/leecreek/lc-isurus.html&menu=bin/menu_topics-alt.html

Most Makos I find in Florida are Isurus hastalis. Occasionally, I find an odd looking Mako that seem not to be. I could not say positively what they are. Is it easy or difficult to differentiate between species of Mako? There seems to be an attempt at unique characteristics in the elasmo thread above.

 

 

Hastalis is not a mako.  It is a great white, Carcharodon hastalis.  Fossil teeth that have been called Isurus desori correspond to the extant Isurus oxyrinchus (Mako Shortfin Shark).  The fossil and extant teeth are so similar that some researchers now use  Isurus oxyrinchus for the fossil teeth.  The tooth in this post could be in the direct lineage of the extant Isurus paucus (Mako Longfin Shark).  Some researchers believe that retroflexus is a direct ancestor of paucus.  Other researchers believe that retroflexus is a giant thresher and not the direct ancestor of I. paucus.  I still think that the tooth in this post is a retroflexus which is either a giant thresher or a mako depending on which shark researchers you believe.  The elasmo.com write-up is outdated and doesn't change my opinion.

 

Marco Sr.

[Shellseeker]

2 hours ago, MarcoSr said:

 

Hastalis is not a mako.  It is a great white, Carcharodon hastalis.  Fossil teeth that have been called Isurus desori correspond to the extant Isurus oxyrinchus (Mako Shortfin Shark).  The fossil and extant teeth are so similar that some researchers now use  Isurus oxyrinchus for the fossil teeth.  The tooth in this post could be in the direct lineage of the extant Isurus paucus (Mako Longfin Shark).  Some researchers believe that retroflexus is a direct ancestor of paucus.  Other researchers believe that retroflexus is a giant thresher and not the direct ancestor of I. paucus.  I still think that the tooth in this post is a retroflexus which is either a giant thresher or a mako depending on which shark researchers you believe.  The elasmo.com write-up is outdated and doesn't change my opinion.

 

Marco Sr.

I was not attempting to change your identification of this tooth. I do not know enough to even try. The whole discussion seems confusing. I was trying to learn something about how complicated it is to discuss the identification of "Mako".

 

It seems from your response that it is incredibly complicated with numerous name changes and researchers in direct disagreements.

[MarcoSr]

3 hours ago, Shellseeker said:

I was not attempting to change your identification of this tooth. I do not know enough to even try. The whole discussion seems confusing. I was trying to learn something about how complicated it is to discuss the identification of "Mako".

 

It seems from your response that it is incredibly complicated with numerous name changes and researchers in direct disagreements.

 

I don't use ID labels in any of my shark tooth displays because there have been way too many fossil shark name changes over the 46 years that I have been collecting shark teeth.  There has been a good amount of evolution in the thinking about a number of species originally thought to be Isurus or makos.  Not all shark researchers are in full agreement on the changes.  To further complicate the Isurus story, I expect at some point in the future Isurus planus to have a genus change and not be considered a mako either.

 

Marco Sr.