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HemiHunter

Calvert Cliffs - Hemis for the HemiHunter

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Ludwigia

Nice finds. Sorry I can't help with id, but there are still enough people in the know lurking here.

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Gizmo

Very nice, congrats! :)

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FossilsAnonymous

@HemiHunter

Nice vert.

For the tooth, either a symph or some sort of pathology. Based on the root, it’s a Lemon with a severe pathology.

In your big picture showing all your finds, the root looks very similar to the tooth on the immediate left, which is a Lemon, or Negaprion.sp, very common teeth at Calvert Cliffs.

However, it could possibly be one of the scattered Carcharinids with a servere pathology, because it is a bit thicker than the average Lemon root.

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hokietech96

Great finds!  Love the vert and hemis

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Andy B

Very nice!

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Familyroadtrip

I love the hemis and the vert!!!

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siteseer
On 6/30/2020 at 11:19 AM, FossilsAnonymous said:

@HemiHunter

Nice vert.

For the tooth, either a symph or some sort of pathology. Based on the root, it’s a Lemon with a severe pathology.

In your big picture showing all your finds, the root looks very similar to the tooth on the immediate left, which is a Lemon, or Negaprion.sp, very common teeth at Calvert Cliffs.

However, it could possibly be one of the scattered Carcharinids with a servere pathology, because it is a bit thicker than the average Lemon root.

 

The root lobes seem to branch out too far to be a symphyseal.  It seems too broad at the crown base to be a carcharhinid and a broader carcharhinid would have serrated cutting edges.  I think it could be an irregular mako with an eroded root.  It is weird - cool tooth.  That's a great shark centrum too.

 

Maybe a few others will take a look.   @isurus90064  @MarcoSr @sagacious  @Al Dente  @sixgill pete  and everyone else I can't think of at the moment.

 

Jess

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MarcoSr
8 hours ago, siteseer said:

 

The root lobes seem to branch out too far to be a symphyseal.  It seems too broad at the crown base to be a carcharhinid and a broader carcharhinid would have serrated cutting edges.  I think it could be an irregular mako with an eroded root.  It is weird - cool tooth.  That's a great shark centrum too.

 

Maybe a few others will take a look.   @isurus90064  @MarcoSr @sagacious  @Al Dente  @sixgill pete  and everyone else I can't think of at the moment.

 

Jess

 

I would like to see a picture of the labial side.  It might be an Anotodus retroflexus.  If not probably a C. hastalis or I. desori.

 

Marco Sr.

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WhodamanHD

That’s a cool tooth, my two cents say extreme posterior Isurus retroflexus

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HemiHunter

Thanks for taking a look, guys. I looked at the Isurus dentition and it didn't even have an extreme posterior to show, so it's still unlcear to me. Here are some more views.

20200703_131317.jpg

20200703_131152.jpg

20200703_131019.jpg

20200703_130917.jpg

20200703_130827.jpg

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siteseer

To be a C. hastalis posterior of that size I would expect the crown to be more slender and pointed toward and at the tip.  I think it could be I. retroflexus (following Kent, 2018, and his argument against assignment to Anotodus) but I'd like to see a direct profile shot.  I retroflexus has very labiolingually-compressed (flattened) crowns and the one profile shot is a little at an angle.  I don't think I've seen a retroflexus posterior before but this might be it.

 

If not retroflexus, then I would say I desori/early I. oxyrinchus.

 

Jess

 

 

Kent, B. W.  2018.
The Cartilaginous Fishes (Chimaeras, Sharks, and Rays) of Calvert Cliffs, Maryland, USA.  In: The Geology and Vertebrate Paleontology of Calvert Cliffs, Maryland. edited by S. J. Godfrey: (ed.): 45-157

 

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MarcoSr
11 hours ago, WhodamanHD said:

That’s a cool tooth, my two cents say extreme posterior Isurus retroflexus

 

3 hours ago, siteseer said:

To be a C. hastalis posterior of that size I would expect the crown to be more slender and pointed toward and at the tip.  I think it could be I. retroflexus (following Kent, 2018, and his argument against assignment to Anotodus) but I'd like to see a direct profile shot.  I retroflexus has very labiolingually-compressed (flattened) crowns and the one profile shot is a little at an angle.  I don't think I've seen a retroflexus posterior before but this might be it.

 

If not retroflexus, then I would say I desori/early I. oxyrinchus.

 

Jess

 

 

Kent, B. W.  2018.
The Cartilaginous Fishes (Chimaeras, Sharks, and Rays) of Calvert Cliffs, Maryland, USA.  In: The Geology and Vertebrate Paleontology of Calvert Cliffs, Maryland. edited by S. J. Godfrey: (ed.): 45-157

 

 

There is definite disagreement among researchers concerning the genus of retroflexus.  I agree with both Herman and Cappetta that the genus should be Anotodus and that retoflexus was a giant Alopidae.  My son Mel built a retroflexus dentition from the hundreds of retroflexus teeth that he has and compared this dentition with both the numerous extant Alopias and Isurus jaws that I have and to the many fossil thresher and giant thresher and mako teeth (Mel and I also agree that hastalis is a great white and not a mako) that we have.  After his own personal analysis he was convinced that retroflexus was a giant Alopidae.  After what he showed me, I'm convinced that retroflexus is a giant Alopidae.  But truthfully this disagreement and all of the other genus name changes over the years is why I don't label my fossil shark teeth.  The big problem that I have with a number of the shark researchers is that they are not experts on the extant sharks.  The extant sharks should be a baseline for understanding the fossil sharks.  Also associated fossil shark dentitions, although rare, should be another baseline.  I see so much in the hundreds of extant shark jaws that I have, and the hundreds of thousands of shark teeth that I have found in 48 years of collecting that makes me question the analysis and conclusions in a number of papers that I have read including Kent 2018 on Anotodus.

 

Marco Sr.

 

 

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WhodamanHD
37 minutes ago, MarcoSr said:

The big problem that I have with a number of the shark researchers is that they are not experts on the extant sharks.

I completely agree, lack of extant shark research is a massive problem which deserves more research and funding. We have no idea exactly how variable extant shark teeth are, we have only sparse information on ontogenetic changes, and little if any on sexual dimorphism. The present is the key to understanding the past. I really wish there was a more comprehensive source of shark dentitions, Elasmo has a small one but sometimes the actual positions are hard to make out. 
 

I have gone back and forth on whether it’s a giant alopiid or the precursor to The longfin mako. Currently, I’m more inclined towards Isurus but who knows what the future holds

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MarcoSr
7 hours ago, WhodamanHD said:

I completely agree, lack of extant shark research is a massive problem which deserves more research and funding. We have no idea exactly how variable extant shark teeth are, we have only sparse information on ontogenetic changes, and little if any on sexual dimorphism. The present is the key to understanding the past. I really wish there was a more comprehensive source of shark dentitions, Elasmo has a small one but sometimes the actual positions are hard to make out. 
 

I have gone back and forth on whether it’s a giant alopiid or the precursor to The longfin mako. Currently, I’m more inclined towards Isurus but who knows what the future holds

 

The lack of extant shark research is a shame.  It is even worse for extant rays.  The next shakeup of shark genera/species will come from DNA testing.  I keep reading little bits about current ongoing shark DNA testing but the few papers I've seen published have been pretty preliminary and somewhat disappointing to me.

 

Science moves forward not only with agreement but also with disagreement.  There are currently, have been in the past and will be in the future disagreements over shark genera.  Only new research moves us forward.

 

Marco Sr.

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HemiHunter

Here are some more profiles, in case they will help.

20200704_095236.jpg

20200704_095054.jpg

20200704_094857.jpg

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sagacious

As noted above, since this tooth has an incomplete root, and is apparently missing some basal enamel, it's difficult to give more than one's impression.  Like others, my immediate impression was of I retroflexus.  To my eye, this tooth does not look like it exhibits any obvious pathology.

 

This tooth doesn't look like C hastalis to me.  Just to go though the hoops, I tried to find something vaguely similar in a large lot of rearmost posterior C hastalis.  Of that proportion of this collection which have distally-directed crowns, the crowns are still more upright and narrower than the question tooth, with the root width proportionately narrower, although there is quite a lot of variation.  So, this reiterates Siteseer's previous comments on C hastalis. 

 

I don't have any I retroflexus posterior teeth to compare.  So working with what I had on hand, I looked through a bunch of other Isurus sp posteriors, noting that for the same position there was seemingly some variation in crown thickness.  I don't know if this is ontogenetic, or gender-specific, or incorrectly assessed, or what -- but it seems that slight variation in Isurus, as in Carcharodon, is to some extent almost a defining trait. So, if this tooth looks slightly unusual, maybe that's not too unusual in itself.

 

Eric

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HemiHunter

Thanks to everyone for all their help trying to identify this tooth! Honestly, I almost didn't bother collecting it except for its odd appearance. Based on the above, the best guess seems to be that it's a posterior retroflexus lower, correct?.  It also seems that it may be a rare tooth as some of you said you haven't seen one.  So is it of some scientific value to a researcher who might like to see it in hand, or should I just be happy to have it in my little collection to look at and talk about from time to time?

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WhodamanHD
2 hours ago, HemiHunter said:

So is it of some scientific value to a researcher who might like to see it in hand, or should I just be happy to have it in my little collection to look at and talk about from time to time?

I’ll PM you the CMM collection managers E-mail so you can ask him if he wants it if you so chose.

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siteseer
On 7/3/2020 at 8:10 PM, MarcoSr said:

 

 

There is definite disagreement among researchers concerning the genus of retroflexus.  I agree with both Herman and Cappetta that the genus should be Anotodus and that retoflexus was a giant Alopidae.  My son Mel built a retroflexus dentition from the hundreds of retroflexus teeth that he has and compared this dentition with both the numerous extant Alopias and Isurus jaws that I have and to the many fossil thresher and giant thresher and mako teeth (Mel and I also agree that hastalis is a great white and not a mako) that we have.  After his own personal analysis he was convinced that retroflexus was a giant Alopidae.  After what he showed me, I'm convinced that retroflexus is a giant Alopidae.  But truthfully this disagreement and all of the other genus name changes over the years is why I don't label my fossil shark teeth.  The big problem that I have with a number of the shark researchers is that they are not experts on the extant sharks.  The extant sharks should be a baseline for understanding the fossil sharks.  Also associated fossil shark dentitions, although rare, should be another baseline.  I see so much in the hundreds of extant shark jaws that I have, and the hundreds of thousands of shark teeth that I have found in 48 years of collecting that makes me question the analysis and conclusions in a number of papers that I have read including Kent 2018 on Anotodus.

 

Marco Sr.

 

 

 

Hi Marco Sr.,

 

Would your son, Mel. be willing to show us his dentition?  I would like to see it.  I must also say "Wow" to anyone who has hundreds of retroflexus teeth.  I might have ten total.

 

I'm not sure you can blame shark researchers completely for not being experts on modern sharks.  You'd be surprised how few properly-curated modern shark jaws there are in large museums worldwide.  When some researchers need well-curated modern jaws (total length, sex, location, depth caught, etc.) for comparison, they fly out to visit Dr. Gordon Hubbell.  He has been meticulous in recording that data for all the specimens he keeps and he's been doing it for decades.  He welcomes researchers of all levels including schoolkids.

 

Many sharks are threatened species so it has been be problematic in recent years to try to build a collection of curated specimens for an institution. 

 

Studying modern sharks to understand extinct ones started with Maurice Leriche, a Belgian paleontologist, who lived across the turn of the century (19th to 20th, that is).  He was apparently the first one to think about shark and ray teeth from the standpoint of the dentition rather than as isolated teeth.  Many of today's paleontologists know his articles well and have worked to build on his research.

 

Jess

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siteseer
7 hours ago, HemiHunter said:

Thanks to everyone for all their help trying to identify this tooth! Honestly, I almost didn't bother collecting it except for its odd appearance. Based on the above, the best guess seems to be that it's a posterior retroflexus lower, correct?.  It also seems that it may be a rare tooth as some of you said you haven't seen one.  So is it of some scientific value to a researcher who might like to see it in hand, or should I just be happy to have it in my little collection to look at and talk about from time to time?

 

HemiHunter,

 

Thanks for the extra profile views.  I think the crown is too thick to be retroflexus, a species known for its labiolingually-compressed crowns or are the posteriors like that?  You should try contacting Bretton Kent.  It would be interesting to get his opinion too.

 

Jess

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siteseer
On 7/5/2020 at 5:53 PM, sagacious said:

As noted above, since this tooth has an incomplete root, and is apparently missing some basal enamel, it's difficult to give more than one's impression.  Like others, my immediate impression was of I retroflexus.  To my eye, this tooth does not look like it exhibits any obvious pathology.

 

This tooth doesn't look like C hastalis to me.  Just to go though the hoops, I tried to find something vaguely similar in a large lot of rearmost posterior C hastalis.  Of that proportion of this collection which have distally-directed crowns, the crowns are still more upright and narrower than the question tooth, with the root width proportionately narrower, although there is quite a lot of variation.  So, this reiterates Siteseer's previous comments on C hastalis. 

 

I don't have any I retroflexus posterior teeth to compare.  So working with what I had on hand, I looked through a bunch of other Isurus sp posteriors, noting that for the same position there was seemingly some variation in crown thickness.  I don't know if this is ontogenetic, or gender-specific, or incorrectly assessed, or what -- but it seems that slight variation in Isurus, as in Carcharodon, is to some extent almost a defining trait. So, if this tooth looks slightly unusual, maybe that's not too unusual in itself.

 

Eric

 

Hi Eric,

 

It's great to see you get in on this discussion.

 

Jess

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MarcoSr
5 hours ago, siteseer said:

 

Hi Marco Sr.,

 

Would your son, Mel. be willing to show us his dentition?  I would like to see it.  I must also say "Wow" to anyone who has hundreds of retroflexus teeth.  I might have ten total.

 

Jess

 

Jess

 

I purchased Cappetta 2012 before it was released and received a copy right after it was published.  I noticed retroflexus was changed from Isurus to Anotodus soon after I received the copy.  I asked Mel to change the genus on our Phatfossils website as a result.  Mel said originally that it was crazy that retoflexus was a giant thresher.  I kept bugging him and he decided to look at his retroflexus teeth along with his fossil giant threshers, threshers, makos and borrowed my mako and thresher jaws.  Mel has thousands of self-collected megs, thousands of self collected hastalis but only a couple hundred self-collected retroflexus.  He has posted videos of only his very nicest of these teeth which he has in metal map chests.  He literally has boxes of them.  About a month after I lent him the jaws, he called me up and said that he changed Phatfossils because he was convinced after looking at the fossil teeth and extant jaws that retroflexus was a giant thresher.  He sent to me a number of pictures proving the point.  That was at least 7 years ago.  I lost all of the pictures when my hard drive crashed 3 years or so ago along with thousands of other shark and ray tooth pictures that I had or I would post them.  I don't know if Mel still has the pictures or if the dentition is still together but I'll ask him.  The vast majority of Mel's fossils wound up in Marco Jr.'s basement in a ton of boxes when Mel moved to South Dakota.

 

My belief is that I. desori is the direct ancestor of I. oxyrinchus.  The teeth look so similar that some researchers don't even use I. desori for the fossil teeth anymore but use I. oxyrinchus instead.  Retroflexus went extinct.  I. paucus then branched off of the desori-oxyrinchus lineage to fill the niche left by retroflexus.  Since paucus was eating the same prey as retroflexus its teeth through convergent evolution developed some of the features that were similar to retroflexus.  Extant I. paucus teeth to me look much more like desori than they do retroflexus.  If you compare the extant jaws of I. paucus with I. oxyrinchus the teeth features are very similar.  However, if you look at the upper anterior tooth features especially, the size of the gap between the intermediate tooth and the first lateral tooth, and count the tooth files you can easily tell the jaws apart.

 

Edit:  It will take more research to determine the direct ancestor of I. paucus.  Finding and describing either a transitional retroflexus or a transitional desori-oxyrinchus  would resolve this question.

 

 

Marco Sr.

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WhodamanHD

Someone posted these retros on Facebook, they are not associated but he was making them into dentitions. I kept the pictures with his permission.

5E90ACE3-9EAF-47A7-95B5-C32CACBE7B8D.jpeg

F48F031F-4B73-4E9D-B098-CC961195A7D1.jpeg

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MarcoSr
13 hours ago, WhodamanHD said:

Someone posted these retros on Facebook, they are not associated but he was making them into dentitions. I kept the pictures with his permission.

5E90ACE3-9EAF-47A7-95B5-C32CACBE7B8D.jpeg

F48F031F-4B73-4E9D-B098-CC961195A7D1.jpeg

 

 

Thank you for posting this.  Makes me rethink the Isurus to Anotodus change.  However, I'm not convinced that all of the above teeth are retroflexus.  Some definitely are.  Some look more like desori/hastalis/alopias to me.  Important to me are the teeth shown as intermediate (some researchers don't use intermediate for this position and instead call it A3) really retroflexus intermediate teeth?  Some look more alopias to me but also possibly from just much smaller retroflexus sharks.  Also in the extant I. paucus jaws the intermediate tooth is much smaller than the 2nd upper anterior like above but only slightly bigger than the first lateral totally unlike the above.  If retroflexus had intermediate teeth it wouldn't be a thresher.  Also I question the upper anterior teeth here and on elasmo.  Mel has anterior upper teeth that are much broader and from the labial shoulders are clearly retroflexus.  I think some of the teeth shown as laterals next to the intermediate teeth are the true anterior teeth.  I also question the lower parasymphyseals.  The extant threshers don't have lower parasymphyseals edit: (incorrect statement, see posts that follow) but neither do the extant makos.  If you want a dentition to look like a mako, you pick certain fossil teeth by size and features and then arrange them in a certain way like above.  If you take the same teeth above, remove those teeth that may not be retroflexus or are possibly from much smaller sharks, and arrange them in a certain way, you can make the above teeth look like a giant thresher.  The best way to end the debate is to find an articulated jaw but the odds of that are near zero.  An associated set of teeth should also resolve the issue but I've seen different researchers reassemble associated teeth in a different way to support their point of view. 

 

Marco Sr.

Edited by MarcoSr
Note an incorrect statement

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