Symphyseal / Parasymphyseal Meg Teeth?

[sixgill pete]

Is this tooth position known from Megalodon. I know it is from Otodus / Auriculatus, but I have never heard of it from Angustidens, Chubutensis or Megalodon.

I recently found a tooth that has been suggested could be a meg para / symphyseal. I originally though posterior, but when posting here a few members suggested the thought of symphyseal. The reason is the height of the crown and the small size of the tooth. It is much taller than you would expect from a posterior and it is only 8mm long by 7mm wide.

This is the tooth in question .....

[Auspex]

Are you 100% on it's being a Meg?

[sixgill pete]

Are you 100% on it's being a Meg?

It came from Lee Creek. Either meg or chub as far as I know. But, I am open to any and all thoughts.

[Sharks of SC]

Hey-o Pete,

I would agree that this is probably a symphyseal/parasymphyseal tooth and here's why...

Most of the smaller meg/chub/angustiden teeth that I find are clearly either from a posterior position or a juvenile individual. The posteriors are often wider with slightly thicker roots, while the juveniles are almost proportionate to their adult counterparts, but much smaller.

Here's a grouping of both posterior and juvenile teeth -

In comparison, all of the syphyseal teeth that I've seen have bulbous, undefined roots with quickly-tapering blades. They are usually thicker overall than either a posterior or juvenile tooth of the same size. See...

Mine obviously has some serious curvature, but both teeth follow the same basic formula.

Of course, this is all based on my observation and I would also be quite happy for some clarification from our more experienced tooth-collecting members.

Happy hunting,

CBK

[siteseer]

Sixgill,

I am also leaning toward parasymphyseal, though without a complete/near-complete root, we can't be absolutely sure. However, as noted by CBK, the crown is too high relative to the tooth's overall size to be a posterior. Am I wrong to assume that the coloring and preservation of the tooth makes it more likely a Pungo River Formation specimen rather than a Yorktown tooth? It would be more likely that a meg parasymphyseal would come from the Pungo as that would be an age closer to the ancestors that had that file.

It appears that Otodus had parasymphyseals but not all individuals because they are unusually rare even in deposits where Otodus teeth are abundant and even if you take into consideration that there was only one or two files in a jaw. I have seen a lot more Notidanodon teeth than Otodus parasymphyseals at big mineral/fossil shows and on websites. I know that is hardly scientific but commercial availability does seem to be at least an indicator of actual rarity in this case.

It would appear that the parasymphyseal file was being "phased out" in the lineage as the dentition became more efficient - less teeth able to do the same job. The parasymphyseals were already vestigial in Otodus (and Cretoxrhina too) - reduced versions of teeth that had been useful in an ancestor but still receiving nutrients from the body. At some point an entire generation of Otodus no longer had the file (the anteriors had enlarged and crowded into the space). Still, some individuals would have been born with the file because the gene was still present but deactivated in most of the population, becoming an increasingly rare genetic expression over time.

There was a discussion of possible meg parasymphyseals on the board last year:

http://www.thefossilforum.com/index.php?/topic/31992-symphyseal-meg-tooth/?hl=parasymphyseal#entry352343

Jess

Is this tooth position known from Megalodon. I know it is from Otodus / Auriculatus, but I have never heard of it from Angustidens, Chubutensis or Megalodon.

I recently found a tooth that has been suggested could be a meg para / symphyseal. I originally though posterior, but when posting here a few members suggested the thought of symphyseal. The reason is the height of the crown and the small size of the tooth. It is much taller than you would expect from a posterior and it is only 8mm long by 7mm wide.

This is the tooth in question ..... 100_1069.JPG 100_1073.JPG

[siteseer]

CBK,

I agree with you on Sixgill's tooth but your curved tooth may be a Hemipristis upper lateral - possibly a pathologic. The serrations towards the top look very coarse for a megalodon.

Jess

Hey-o Pete,
I would agree that this is probably a symphyseal/parasymphyseal tooth and here's why...
Most of the smaller meg/chub/angustiden teeth that I find are clearly either from a posterior position or a juvenile individual. The posteriors are often wider with slightly thicker roots, while the juveniles are almost proportionate to their adult counterparts, but much smaller.
Here's a grouping of both posterior and juvenile teeth -
image.jpg

In comparison, all of the syphyseal teeth that I've seen have bulbous, undefined roots with quickly-tapering blades. They are usually thicker overall than either a posterior or juvenile tooth of the same size. See...
image.jpgimage.jpg

Mine obviously has some serious curvature, but both teeth follow the same basic formula.
Of course, this is all based on my observation and I would also be quite happy for some clarification from our more experienced tooth-collecting members.

Happy hunting,
CBK

[Sharks of SC]

Hey Siteseer,

I think the root on Sixgill Pete's tooth may be complete. The last serration at the root curves back in...just a thought.

As far as my tooth goes, I think it's still either C. angustiden or C. megalodon. I think the serious curvature may account for the uneven serrations, and on closer inspection you can just make out where a bourlette would've been. To compound the wierdness of this tooth there's a little (pathologic?) "pinch" in the blade - this little section has no serrations, which may also account for it's seemingly uneven serrations.

My tooth definitely has the complete root (minus a little pitting on the labial side). This is what I meant by the "undefined" root that I've seen in para/symphyseals. Here's another gem on Pete's collection illustrating this notion of the "blob" root - http://www.thefossilforum.com/index.php/topic/26082-help-with-this-tooth/

It may just be one of those things you have to see in person.

Thanks,

CBK

Edited May 9, 2013 by Sharks of SC

[sixgill pete]

Siteseer and CBK, thanks for your responses. The root of this tooth is similar to the root of the Auriculatus (sokolowi) parasymphyseal in the thread CBK linked to. Siteseer was the member who ID'd the tooth for me. There is a small portion of the root missing on the left (from lingual view) side but otherwise the root appears complete.

This is definitely one of the most unique teeth I have found.

[siteseer]

CBK,

Yeah, I knew what you meant by the undefined root. As teeth become vestigial, they simplify in form. By the time of megalodon we might assume the parasymphyseal root would have been more globular than in Otodus (which still showed weakly-developed lobes) or at least was even less likely to follow a consistent form.

What is the age of your tooth (formation?)? Since you are figuring it's angustidens or megalodon, I assume the age is roughly Early Miocene.

It's a weird tooth but I think it could be a Hemipristis because I have seen at least one very similar to that in shape with similar (yet not identical) serrations. I can't be sure especially since it does look mildly pathologic on top of being weird.

According to Kent's "Fossil Sharks of the Chesapeake Bat Region," Hemipristis serra had orthodont tooth histology, bearing a large pulp cavity. Carcharocles had osteodont teeth (no pulp cavity). I wouldn't want you to cut into that tooth just to satisfy anyone's curiosity but that would settle it. Having it imaged (x-ray or CT) might be going overboard unless you have a radiologist friend.

Several years ago, David Ward put to rest the Carcharoides/Triaenodon question by examining some beat-up teeth. Among other characters, the teeth were osteodont, eliminating Triaenodon (orthodont) as an option.

It's fun to look at big teeth and the colorful ones but the weird ones make you write long posts.

Jess

Hey Siteseer,

As far as my tooth goes, I think it's still either C. angustiden or C. megalodon. I think the serious curvature may account for the uneven serrations, and on closer inspection you can just make out where a bourlette would've been. To compound the wierdness of this tooth there's a little (pathologic?) "pinch" in the blade - this little section has no serrations, which may also account for it's seemingly uneven serrations.

My tooth definitely has the complete root (minus a little pitting on the labial side). This is what I meant by the "undefined" root that I've seen in para/symphyseals. Here's another gem on Pete's collection illustrating this notion of the "blob" root - http://www.thefossilforum.com/index.php/topic/26082-help-with-this-tooth/

It may just be one of those things you have to see in person.

Thanks,

CBK

[Sharks of SC]

CBK,

Yeah, I knew what you meant by the undefined root. As teeth become vestigial, they simplify in form. By the time of megalodon we might assume the parasymphyseal root would have been more globular than in Otodus (which still showed weakly-developed lobes) or at least was even less likely to follow a consistent form.

What is the age of your tooth (formation?)? Since you are figuring it's angustidens or megalodon, I assume the age is roughly Early Miocene.

It's a weird tooth but I think it could be a Hemipristis because I have seen at least one very similar to that in shape with similar (yet not identical) serrations. I can't be sure especially since it does look mildly pathologic on top of being weird.

According to Kent's "Fossil Sharks of the Chesapeake Bat Region," Hemipristis serra had orthodont tooth histology, bearing a large pulp cavity. Carcharocles had osteodont teeth (no pulp cavity). I wouldn't want you to cut into that tooth just to satisfy anyone's curiosity but that would settle it. Having it imaged (x-ray or CT) might be going overboard unless you have a radiologist friend.

Several years ago, David Ward put to rest the Carcharoides/Triaenodon question by examining some beat-up teeth. Among other characters, the teeth were osteodont, eliminating Triaenodon (orthodont) as an option.

It's fun to look at big teeth and the colorful ones but the weird ones make you write long posts.

Jess

Hey Jess,

You wouldn't happen to have a picture of the hemipristis or a similar example, would you? I've collected quite a few hemis over the years, but none quite like this tooth.

Uppers, lowers, anteriors, laterals, posteriors, parasymphyseals...just about everything in between -

These represent about a third of the complete hemis I've found over the years...so like 1,200 teeth or something, but never found one like the tooth in question.

I don't have any radiologist friends, unfortunately... Ill put up few more photos of my tooth in the hopes of finding a definitive identification.

Thanks for your continued interest, siteseer. Sixgill, sorry if I hijacked your thread. Ill wrap it up.

Happy hunting,

Cade

[sixgill pete]

Thanks for your continued interest, siteseer. Sixgill, sorry if I hijacked your thread. Ill wrap it up.
Happy hunting,
Cade

No problem at all Cade. Your tooth is very interesting. I would not have thought meg or hemi. However I think I have one similar to yours from Lee Creek, if I can find it, I will post it here also.

Jess as far as the age of my tooth, coming out of a spoil pile that had been spread out, it is hard to be sure. However, I do believe it is from the Pungo.

[Paleoc]

I would definitely think posterior. Posteriors due their crowded position in the jaw are often odd shaped with enlarged or distorted roots. Often they have erect blades and thus appear to be anteriors. Size is irrelevant, lamniforme posteriors are tiny compared to the anterior teeth in the same animal. I have a complete (including replacement teeth) removed dentition from a large mako. The anterior teeth are 2 inches (50mm), the posterior teeth are something like 2-3mm. Take a look at the size of the posterior teeth from the large Great White below compared to the anteriors. I say again, size is irrelevant.

Your tooth appears from an infant chubutensis. Note the diminishing and lack of serrations near the tip.