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WhodamanHD

The Muddle in the Middle of the Meg line

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WhodamanHD

All the time we have a reoccurring theme of a megatoothed shark tooth with no locale info being labeled as unidentifiable. You would think that those ol’scientists had some good reasons for separating the species out (other than time and place). I have been lucky enough to collect all the teeth from the middle of this line and have made some simple observations. I don’t know whether they stand to scrutiny, but I thought I’d share them. Because I really don’t know what the status of Carcharocles is, im going to use Otodus despite Carcharocles being the cooler name by far.

Here it goes:

Otodus Aksauticus 

Fig. 1

Pretty different from Otodus if you asked me. Mine comes from the Early Eocene of Maryland’s Nanjemoy formation. It is Typically early Eocene and a not a very prolific species it seems. The cusp serrations are not very fine, and the blade serrations are large (though not as large as paleocarcharodon) and irregular. May be hard to see in my specimen. This species is probably descended from Otodus obliquus

Otodus auriculatus 

Fig. 3

I believe sokolovi and sokolowi are synonymous, they occur in a number of sites of early- or Mid-Eocene age. I am kind of confused, as I have one that matches the description (and was sold to me as a sokolovi) from Dakhla, Morocco which seems to be late eocene with some late Paleocene deposits (less likely). Take this figure with a generous helping of sodium chloride. These are the first teeth in the lineage that seem to be more common large (2-4 inch slant height it seems) than small. The serrations are slightly finer but still irregular on the blade. The cusp has both large and small serrations. This species probably evolved from Aksauticus (Otodus will be assumed from this point forward).

Otodus sokolovi 

Fig. 2

These are from the mid- late Eocene, and seem to have some degree of regional variation. Mine is from the Late Eocene Harleyville formation of South Carolina. They still tend to keep under 4 inches. Serrations are fine and regular on the blade (because there is a bit of wear on mine it’s hard to see). Cusp serrations are fine but still get large around the point of the cusp. They are probably descended from auriculatus, and are considered by many to be one species. They are here for splitters sake.

Otodus angustidens

Fig. 4

Okay, so embarrassingly enough I have one good (unworn enough for meaningful automorphies to be seen) angustidens, and it’s a juvenile. I hope you’ve taken a grain of salt for this whole thing, but this one should be a nice chunky crystal. Any way, they are most common in the Oligocene (when they appear). They get almost meg-sized, about five inches is the biggest I’ve heard tell of. They have fine, regular serrations on both the blade and the cusp, only minutely larger towards the apex of the cusp. Cusps are also is moving towards the blade as well as becoming more circular as opposed to the more triangular ones possessed by earlier megatooths. Some can be very difficult to tell from auriculatus/sokolovi (from which it is likely to have evolved. Angustidens tends to have a more triangular blade then auriculatus but this is a flimsy standard and doesn't work in many cases.  Mine is from the oligocene Chandler Bridge formation of South Carolina

 

 

So thats it, figures below, thanks to @Nimravis for the magnifying technique. Chubs are a whole different ball game, one which I am not ready to play at the moment. I think I’ll do a thread on it some other time.

hope you enjoyed, please point out any errors or additions! 

 

 

Fig. 1

4AB93E5A-BC5D-4A4D-9C27-F0E9829E0FED.jpeg

68343F46-489E-47F3-B240-7618EE53313A.jpeg

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WhodamanHD

Fig. 2

E4DEF2DF-B2E5-4B8D-8DEB-74EC0BEA28C7.jpeg

FA906AA4-6592-45C7-8C67-B29938A411C7.jpeg

8F9A3056-BE30-4F23-8B45-9238562191D7.jpeg

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WhodamanHD

Fig. 3

 

BD95D175-0222-4487-8BC8-C36C2ED55D13.jpeg

C18C54F7-1848-4C96-9B54-7283E81AAA84.jpeg

6D812754-98F5-4357-9159-03575F015D0A.jpeg

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WhodamanHD

Fig. 4

83903235-6C65-4BA8-A86C-A8E78EC5C07E.jpeg

0E7EC064-63BA-4A69-BE7C-DBB7584928E9.jpeg

85A002DD-38B6-4A46-BD1D-7E6954F3893A.jpeg

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WhodamanHD

Bonus figure

Please note, the size and placement (and in one case life stage) are different for each tooth, and I am not quite skilled enough to tell if that makes a difference.

B2E21AD2-5287-4C87-B4F5-D3C65C065EF5.jpeg

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ynot

Are You done? Can I comment now?

 

Nice presentation and display.

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WhodamanHD
3 minutes ago, ynot said:

Are You done? Can I comment now?

 

Nice presentation and display.

Yeah:D

Thanks!

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Nimravis
28 minutes ago, ynot said:

Are You done? Can I comment now?

 

Nice presentation and display.

I echo Tony's comments.

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WhodamanHD

I tried to remove the thing I put about not commenting while I was still posting, did that work?

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WhodamanHD
2 minutes ago, Nimravis said:

I echo Tony's comments.

Thanks!

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Al Dente
7 hours ago, WhodamanHD said:

I believe sokolovi and sokolowi are synonymous, they occur in a number of sites of Mid-Eocene age. Mine is from the Mid-Eocene site of Dakhla, Morocco (I don’t know the formation). These are the first teeth in the lineage that seem to be more common large (2-3 inch slant height it seems) than small. The serrations are slightly finer but still irregular on the blade. The cusp has both large and small serrations. This species probably evolved from Aksauticus (Otodus will be assumed from this point forward).

Otodus auriculatus 

Fig. 3

These are from the late Eocene, and seem to have some degree of regional variation. Mine is from the Late Eocene Harleyville formation of South Carolina. They still tend to keep under 4 inches, but are more common than sokolovi. Serrations are fine and regular on the blade (because there is a bit of wear on mine it’s hard to see). Cusp serrations are fine but still get large around the point of the cusp. They are probably descended from (you guessed it!) sokolovi. 

Otodus angustidens

I believe the Dakhla site is Late Eocene. I tend to lump these two under auriculatus but I think people who separate them out call the early to mid Eocene form auriculatus and the mid to late Eocene form sokolowi.

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WhodamanHD
1 hour ago, Al Dente said:

I believe the Dakhla site is Late Eocene. I tend to lump these two under auriculatus but I think people who separate them out call the early to mid Eocene form auriculatus and the mid to late Eocene form sokolowi.

Thanks for telling me, that messes up my thoughts on it, especially since sokolovi has features of an older megatooth. This paper  has both from a mid Eocene site where they coexisted, not sure what features they used to seperate them. Is it possible the tooth I bought that is labeled as a sokolovi is an auriculatus and the Harleyville tooth is a sokolovi? If not I’ll have to rethink this again.

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Al Dente
13 minutes ago, WhodamanHD said:

Thanks for telling me, that messes up my thoughts on it, especially since sokolovi has features of an older megatooth. This paper  has both from a mid Eocene site where they coexisted, not sure what features they used to seperate them. Is it possible the tooth I bought that is labeled as a sokolovi is an auriculatus and the Harleyville tooth is a sokolovi? If not I’ll have to rethink this again.

I didn't read the entire paper you referenced but the material the teeth came from is a lag deposit that contains teeth of different ages including many early Eocene teeth mixed with middle Eocene. Have you looked through the Elasmo web site on this subject? It goes through great detail on the change of this chronospecies through time. 

 

Here a clip from the conclusion section of the paper you linked that describes the range of ages of the teeth:

 

rework.JPG

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sixgill pete

I usually go with auriculatus for any Eocene teeth, angustidens for Oligocene teeth. In both of these species I see a difference in the cusps and serrations depending on the exact age of the deposits. We have a local quarry here that has very early Oligocene deposits and late Oligocene deposits. I have sound teeth that that are almost the splitting image of auriculatus, and that really resemble chubutensis. But they are all labelled O. angustidens as they came from Oligocene deposits. No doubt the early teeth and the late teeth are transitional teeth.  If you went solely on the placement of the cusplets and the size and shape of the serrations, you may label these teeth as something they could not be due to the age of the deposits they were found in. 

 

To me the real muddle occurs in the Miocene. When does chubutensis end and megalodon take over. Clouding that is the fact that some juvenile megs have cusplets. 

 

 

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Yvie

Well that's something to chew on.Still not finding teeth down my beach where they are meant to be common!Not.Getting waylaid by the metal detector I have been given and field walking one of the farms 420 acres that I have permission on.Still coming home with rocks even then though,

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WhodamanHD
7 hours ago, Al Dente said:

Have you looked through the Elasmo web site on this subject? It goes through great detail on the change of this chronospecies through time. 

 

I briefly looked at it but after reading it in depth, I have concluded (based on what they say) that my Auriculatus is closer to their description of sokolovi (and the sokolovi looks like the description of the auriculatus). Ill try to edit the post to reflect this. They are chronospecies, very slightly different from each other and the name matters little, but I just want to see what the scientists (albeit splitters) were thinking when they designated the new ones.

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WhodamanHD
5 hours ago, sixgill pete said:

I usually go with auriculatus for any Eocene teeth, angustidens for Oligocene teeth. In both of these species I see a difference in the cusps and serrations depending on the exact age of the deposits. We have a local quarry here that has very early Oligocene deposits and late Oligocene deposits. I have sound teeth that that are almost the splitting image of auriculatus, and that really resemble chubutensis. But they are all labelled O. angustidens as they came from Oligocene deposits. No doubt the early teeth and the late teeth are transitional teeth.  If you went solely on the placement of the cusplets and the size and shape of the serrations, you may label these teeth as something they could not be due to the age of the deposits they were found in. 

 

To me the real muddle occurs in the Miocene. When does chubutensis end and megalodon take over. Clouding that is the fact that some juvenile megs have cusplets. 

 

 

I think that time alone should not seperate species, there must be some differentiating features of the teeth (especially with widely recognized ones like auriculatus and angustidens). They are a gradually evolving lineage which makes lines difficult to draw, but nevertheless there should be some distinguishing features. If I find a chub in the oligocene, I must not say it’s an angustidens just for the sake of time. The whole chub thing though is beyond me at the moment, as there is no definitive line between it, a meg, and an angy. I know these are artificial constructs, but still should put a good line on it.

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WhodamanHD
1 hour ago, Yvie said:

Well that's something to chew on.Still not finding teeth down my beach where they are meant to be common!Not.Getting waylaid by the metal detector I have been given and field walking one of the farms 420 acres that I have permission on.Still coming home with rocks even then though,

Where about are you hunting? There a many factors determining where teeth are common.

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Yvie

Bracklesham Bay UK mainly.Lots of sand coverage lately with the big storms coming on shore,we need one with a northerly wind.

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MarcoSr
On 1/12/2018 at 4:43 AM, Al Dente said:

I believe the Dakhla site is Late Eocene. I tend to lump these two under auriculatus but I think people who separate them out call the early to mid Eocene form auriculatus and the mid to late Eocene form sokolowi.

 

On 1/12/2018 at 6:48 AM, Al Dente said:

I didn't read the entire paper you referenced but the material the teeth came from is a lag deposit that contains teeth of different ages including many early Eocene teeth mixed with middle Eocene. Have you looked through the Elasmo web site on this subject? It goes through great detail on the change of this chronospecies through time. 

 

Here a clip from the conclusion section of the paper you linked that describes the range of ages of the teeth:

 

rework.JPG

 

 

I totally agree with Eric above.

 

You can’t use a sample size of one tooth for each cronospecies to show tooth feature differences between the cronospecies in the Otodus obliquus to megalodon lineage.  There is just too much variation of tooth features within each cronospecies.  I see this first hand with the thousands of teeth that my family has from the lineage.  If you use a sample size of 10 teeth from a single site you should start to see this tooth feature variation.  If you use a sample size of 100 teeth from a single site you should be seeing more of these tooth feature variations within a species.  If you now look at 100 teeth of a species from 10 different US sites you should be seeing more of the variations in tooth features within a species (some of this may be related to age differences of the formations versus differences in local populations versus individual differences).  If you then look at 100 teeth of each species from each of many sites all over the world you would really see the tooth feature variations within the species.  Then when you compared the cronospecies the differences would really be blurred.

 

Look at the date when each of these cronospecies were named (note the original genus of most have changed several times over the years):

 

Otodus obliquus
AGASSIZ, 1843

 

Otodus obliquus mugodzharicus
ZHELEZKO IN ZHELEZKO & KOZLOV, 1999

 

Otodus aksuaticus
MENNER, 1928

 

Otodus (Carcharocles) auriculatus
BLAINVILLE, 1818

 

Otodus sokolovi
JAEKEL, 1895

 

Otodus (Carcharocles) angustidens
AGASSIZ, 1843

 

Otodus (Carcharocles) chubutensis
AGASSIZ, 1843

 

Otodus (Megaselachus) megalodon
AGASSIZ, 1837

 

Many many more teeth of each cronospecies are now in museums from many new sites all over the world.  Researchers need to revisit this entire lineage and determine tooth feature criteria that differentiate each of the named cronospecies.

 

Marco Sr.

 

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