Bails Posted November 24, 2020 Share Posted November 24, 2020 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 1 Quote Link to post Share on other sites
Fossildude19 Posted November 24, 2020 Share Posted November 24, 2020 Are the edged serrated? Quote Link to post Share on other sites
Bails Posted November 24, 2020 Author Share Posted November 24, 2020 @Fossildude19 It doesn’t have serrated edges. Thanks. Quote Link to post Share on other sites
Shellseeker Posted November 24, 2020 Share Posted November 24, 2020 From our TFF members Gallary 1 Quote Link to post Share on other sites
Bails Posted November 24, 2020 Author Share Posted November 24, 2020 Thanks! Quote Link to post Share on other sites
bthemoose Posted November 24, 2020 Share Posted November 24, 2020 Wait for others, but I believe this is Isurus retroflexus. It's a gorgeous tooth! Quote Link to post Share on other sites
Bails Posted November 24, 2020 Author Share Posted November 24, 2020 Yeah I think that’s a safe bet and thanks! Quote Link to post Share on other sites
MarcoSr Posted November 24, 2020 Share Posted November 24, 2020 (edited) 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 Quote Link to post Share on other sites
WhodamanHD Posted November 25, 2020 Share Posted November 25, 2020 I’m also in the retroflexus camp Quote Link to post Share on other sites
Shellseeker Posted November 25, 2020 Share Posted November 25, 2020 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. Quote Link to post Share on other sites
MarcoSr Posted November 25, 2020 Share Posted November 25, 2020 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. 1 Quote Link to post Share on other sites
Shellseeker Posted November 25, 2020 Share Posted November 25, 2020 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. Quote Link to post Share on other sites
MarcoSr Posted November 25, 2020 Share Posted November 25, 2020 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. 1 Quote Link to post Share on other sites
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