3 more curious shark teeth from South Carolina

[debivort]

I think I know the species of these teeth, but they have strange features, and I wonder if they are pathological or (para)symphyseal. 

 

G — I think this is a giant thresher tooth. However, it seems unusual in having a cusplet-like fold of enamel on one shoulder (marked by the red asterisks). From Morris Island, SC USA

 

 

H — O. angustidens, one cusplet appears typical but one is very muted. Root is also relatively tall. From Morris Island, SC USA.

 

 

I — Similar to H...  O. angustidens, one cusplet appears typical but one is very muted. Some enamel damage, but I don't think it extends over the "muted" cusplet. From Summerville, SC USA.

[Meganeura]

18 minutes ago, debivort said:

 

I — Similar to H...  O. angustidens, one cusplet appears typical but one is very muted. Some enamel damage, but I don't think it extends over the "muted" cusplet. From Summerville, SC USA.

So prefacing this by saying I know very little of O. Angustidens - but assuming this isn't a tiger shark of some kind (And I don't believe it is, based on the serrations on the inside of the curve) - it may be that extreme posterior teeth like this one just only have the cusp on one side.

[debivort]

This paper suggests there may have been an Angustidens nursery at this deposit - these may be juvenile or neonate teeth. 

"A megatoothed shark (Carcharocles angustidens) nursery in the Oligocene Charleston Embayment, South Carolina, USA" 
https://pdfs.semanticscholar.org/4252/313ba704fda986b73a8b21b05fa3be01634d.pdf

 

In that paper there are a number of images of juvenile L4 and L5 teeth with cusplets on both sides. 

 

[debivort]

bumping for eyeballs

[debivort]

@jikohr @ThePhysicist @Shellseeker — would love your thoughts here. (and any suggestion on who else might appreciate being tagged).

[Shellseeker]

16 minutes ago, debivort said:

@jikohr @ThePhysicist @Shellseeker — would love your thoughts here. (and any suggestion on who else might appreciate being tagged).

I am hunting Southwest Florida... I wish we did , but we do not have Carcharocles angustidens down here. ONLY one I ever found ,  Zolfo Springs, Peace River 2012... My partner that day found a Giant Thresher with serrations... amazing !!! Never saw that again , either

[jikohr]

47 minutes ago, debivort said:

@jikohr @ThePhysicist @Shellseeker — would love your thoughts here. (and any suggestion on who else might appreciate being tagged).

Sure, I'll give what I can.

I agree that the last two are posterior Angustidens.

The first one I'm honestly not entirely sure what that little bump is and I'm not to experienced with the Giant Thresher, but at least to me it seems consistent with one.

Nice teeth either way!

[debivort]

2 hours ago, Shellseeker said:

I am hunting Southwest Florida... I wish we did , but we do not have Carcharocles angustidens down here. ONLY one I ever found ,  Zolfo Springs, Peace River 2012... My partner that day found a Giant Thresher with serrations... amazing !!! Never saw that again , either

Which of these is shown in your photo? Because this is a great match to my tooth H — down to the tall root and muted cusplet on one side.

[Shellseeker]

38 minutes ago, debivort said:

Which of these is shown in your photo? Because this is a great match to my tooth H — down to the tall root and muted cusplet on one side.

I am sorry for the confusion.  Pictured is the tooth that I found a decade ago in the Peace River Florida. I have always considered this tooth (and other Megalodon like teeth) found in the Peace River with cusps to be juvenile O. megalodon with a regressive gene to trigger the cusp.  At far as I can determine , there has never been a verified Angy, Ric, or Chub found in the Peace River.

[debivort]

2 hours ago, Shellseeker said:

I am sorry for the confusion.  Pictured is the tooth that I found a decade ago in the Peace River Florida. I have always considered this tooth (and other Megalodon like teeth) found in the Peace River with cusps to be juvenile O. megalodon with a regressive gene to trigger the cusp.  At far as I can determine , there has never been a verified Angy, Ric, or Chub found in the Peace River.

Maybe my "angustidens" (H) is a regressed megalodon - both species are present in SC dredge spoils! 

[Fin Lover]

Unfortunately, it will be really difficult to determine that, since you can find both here (and don't forget chubs).

[debivort]

1 hour ago, Fin Lover said:

Unfortunately, it will be really difficult to determine that, since you can find both here (and don't forget chubs).

This paper has images of angustidens ID'd teeth that look very chub like to me:
https://pdfs.semanticscholar.org/4252/313ba704fda986b73a8b21b05fa3be01634d.pdf

 

 

I guess the point is that the variability within a species will always leave some distinctions ambiguous. 

But, do you have any thoughts about the tall root and asymmetric cusplets of (H) and (I)? Setting aside species, do these features say anything about position or pathology?

 

Or any thoughts about the enamel nubbin of (G)?

[Fin Lover]

I've seen a few teeth on YouTube videos that they called angustidens, but I would have called chubs, so yes, I agree that there is a lot of variability. I have to agree with the others that the angustidens look posterior, but I don't know whether any of the teeth are pathological as well.

[debivort]

I found a relevant passage in this paper: https://www.tandfonline.com/doi/pdf/10.1080/02724634.2018.1546732

"In posterolateral tooth positions, as teeth become increasingly more asymmetric, lateral cusplets on the mesial and distal edges become disproportionate. Specifically, the cusplet on the distal edge becomes more pronounced than that of the mesial edge (Fig. 3E, F). This could be attributed to a number of things: tooth size, tooth shape, or replacement rate. "

 

 

I think this closes the case — the teeth are not pathological, and the cusplet asymmetry is something that happens with some regularity in far posterior angustidens teeth.
 

[debivort]

Still hoping for some insight on (G)!

[Shellseeker]

5 hours ago, debivort said:

Maybe my "angustidens" (H) is a regressed megalodon - both species are present in SC dredge spoils! 

Not sure that I am adding anything here.  Over a Decade 25 , they all are under 2 inches,  but they have to be Megs with cusps.  None of the others here.

[Fin Lover]

@Shellseeker, yes, you are adding something...confusion. 

@debivort, thanks for the link. I remember seeing that paper a couple months ago, but I think I skipped through parts of it. When even the experts conducting the study found it difficult to tell species apart based on teeth, I decided it was way above my pay grade.   It seems a little easier to read now, so I guess I have been learning.

Edited July 16, 2022 by Fin Lover

[debivort]

50 minutes ago, Shellseeker said:

Not sure that I am adding anything here.  Over a Decade 25 , they all are under 2 inches,  but they have to be Megs with cusps.  None of the others here.

Do you think your tooth is from a posterior position? This is the next passage from that paper:

 

"Personal observations of modern dentitions of Carcharodon carcharias in the private collection of Gordon Hubbell revealed that posterior tooth positions are more crowded and retain juvenile characteristics longer relative to anterior teeth. This may explain why the posterior tooth found in the upper Miocene St. Marys Formation still retained a lateral cusplet.

 

Purdy et al. (2001) also noted the disproportionate presence of lateral cusplets in an associated dentition of Carcharocles chubutensis (USNM 411881, referred to as Carcharodon subauriculatus by Purdy et al., 2001). This specimen lacks lateral cusplets in anterior tooth positions but retains well-developed cusplets in posterolateral tooth positions"

 

St. Marys Formation is the most recent in their analysis, at 10.4-7.6 Ma, and the teeth from it reckoned to be more meg-like than chub-like.

[Meganeura]

7 hours ago, Shellseeker said:

Not sure that I am adding anything here.  Over a Decade 25 , they all are under 2 inches,  but they have to be Megs with cusps.  None of the others here.

Don’t we have Chubs in Florida? I’ve heard that the Bone Valley formation at the very least had some, so it stands to reason that the peace River formation also does?

[Meganeura]

6 hours ago, debivort said:

Do you think your tooth is from a posterior position? This is the next passage from that paper:

 

"Personal observations of modern dentitions of Carcharodon carcharias in the private collection of Gordon Hubbell revealed that posterior tooth positions are more crowded and retain juvenile characteristics longer relative to anterior teeth. This may explain why the posterior tooth found in the upper Miocene St. Marys Formation still retained a lateral cusplet.

 

Purdy et al. (2001) also noted the disproportionate presence of lateral cusplets in an associated dentition of Carcharocles chubutensis (USNM 411881, referred to as Carcharodon subauriculatus by Purdy et al., 2001). This specimen lacks lateral cusplets in anterior tooth positions but retains well-developed cusplets in posterolateral tooth positions"

 

St. Marys Formation is the most recent in their analysis, at 10.4-7.6 Ma, and the teeth from it reckoned to be more meg-like than chub-like.

They’re definitely posterior teeth that @Shellseeker posted - small and curved like that. Well, the first one is. The second straight one doesn’t look to be posterior at all.

[debivort]

3 hours ago, Meganeura said:

They’re definitely posterior teeth that @Shellseeker posted - small and curved like that. Well, the first one is. The second straight one doesn’t look to be posterior at all.

I'm reasonably convinced the second (H) is also a posterior tooth, in a position far enough back to get the asymmetrical cusplets, likely of a neonate given its size. The following is pretty close match from the Miller et al paper:

[debivort]

Just now, debivort said:

I'm reasonably convinced the second (H) is also a posterior tooth, in a position far enough back to get the asymmetrical cusplets, likely of a neonate given its size. The following is pretty close match from the Miller et al paper:

That said, I'm open to alternative hypotheses if you have one, @Meganeura!

[Meganeura]

4 hours ago, debivort said:

That said, I'm open to alternative hypotheses if you have one, @Meganeura!

I’m in agreement with you there!

[ThePhysicist]

G does look like a giant thresher, the wave in the enamel on the shoulder could be pathological.

[Shellseeker]

22 hours ago, debivort said:

Do you think your tooth is from a posterior position? This is the next passage from that paper:

Some of my Megs with cusps are posterior teeth, but maybe in the same proportions that exist in the general Meg population. That 2015 Meg I posted above is about as far from "posterior" as you can get.

It also does not look like other Megs, but can not be anything else.

15 hours ago, Meganeura said:

Don’t we have Chubs in Florida? I’ve heard that the Bone Valley formation at the very least had some, so it stands to reason that the peace River formation also does?

I heard that same rumor 10 years ago.  Can you should me one of those "Chubs"  from Bone Valley Phosphate Mines ? or more importantly , a photo of any Chub found in the Peace River, ...

Mark me down for a non_believer until I see the evidence from a credible source. I would believe Harry if he told me he found a Chub in the Peace River...