Possible Hemipristis Symphseal tooth found in Possum Creek Gainesville?

[VAfossilguy]

Found this little Hemipristis tooth. Looks like a possible symphseal. Is complete except for a small ding on one side. Has very small ridges on outer side and couple larger points on inside. Very strange looking tooth. 

[sixgill pete]

Nope sorry. Not a symphyseal Yes it is a H. serra probably a posterior. This is what a hemi symphyseal looks like .... 

 

[Doctor Mud]

I would say this is a lateral.

 

Here is an image of the jaw of extant Hemipristis.

 

 

http://www.elasmo.com/selachin/slides/ss_dentition.html?sp=he

 

there was no mention here of Parasymphyseals only that the first two files (central teeth) are Parasymphyseal like.

 

@MarcoSr would know if Hemipristis has Parasymphyseals. But I think this is a lateral.

[MarcoSr]

18 minutes ago, Doctor Mud said:

I would say this is a lateral.

 

Here is an image of the jaw of extant Hemipristis.

 

 

http://www.elasmo.com/selachin/slides/ss_dentition.html?sp=he

 

there was no mention here of Parasymphyseals only that the first two files (central teeth) are Parasymphyseal like.

 

@MarcoSr would know if Hemipristis has Parasymphyseals. But I think this is a lateral.

 

The terminology used for the teeth in the symphysis area of a shark jaw has not been standardized.  Different researchers use different terminology for the same tooth positions.  The extant Hemipristis elongatus have both upper jaw and lower jaw symphyseal and medial teeth files in the convention that I use.  The below pictures are from one of the jaws in my collection.

Hemipristis elongatus (Snaggletooth Shark) Upper jaw symphysis showing two files of symphyseal teeth (blue) and one file of medial teeth (red):

 

 

Hemipristis elongatus (Snaggletooth Shark) Lower jaw symphysis showing two files of symphyseal teeth (blue) and one file of medial teeth (red). Note a partial separation of the lower jaw at the symphysis moved the teeth relative to each other and made it very difficult to show them:

l and medial teeth files.

 

The tooth in this post is definitely not a symphyseal tooth.

 

There isn't standard agreement among researchers on which shark teeth positions are laterals and which are posteriors for most shark species.  Where the change occurs in a shark jaw can be quite arbitrary depending on the researcher.  For many shark families that terminology doesn't even make sense because there is not enough tooth feature difference.

 

Marco Sr.   

[Doctor Mud]

Thanks @MarcoSr if there was an extremely informative button I would click that.

 

Is it true that symphyseal teeth are not lost or replaced like other files?

This is usually a claim for rarity of symphyseal teeth.

 

 

[VAfossilguy]

2 hours ago, MarcoSr said:

 

The terminology used for the teeth in the symphysis area of a shark jaw has not been standardized.  Different researchers use different terminology for the same tooth positions.  The extant Hemipristis elongatus have both upper jaw and lower jaw symphyseal and medial teeth files in the convention that I use.  The below pictures are from one of the jaws in my collection.

 

 

Hemipristis elongatus (Snaggletooth Shark) Upper jaw symphysis showing two files of symphyseal teeth (blue) and one file of medial teeth (red):

 

 

 

Hemipristis elongatus (Snaggletooth Shark) Lower jaw symphysis showing two files of symphyseal teeth (blue) and one file of medial teeth (red). Note a partial separation of the lower jaw at the symphysis moved the teeth relative to each other and made it very difficult to show them:

 

l and medial teeth files.

 

The tooth in this post is definitely not a symphyseal tooth.

 

There isn't standard agreement among researchers on which shark teeth positions are laterals and which are posteriors for most shark species.  Where the change occurs in a shark jaw can be quite arbitrary depending on the researcher.  For many shark families that terminology doesn't even make sense because there is not enough tooth feature difference.

 

Marco Sr.   

What explains the strange form and serration of this tooth? 

[ynot]

4 minutes ago, VAfossilguy said:

What explains the strange form and serration of this tooth? 

Tooth position in the jaw and species of shark. It is a typical back of jaw tooth for a hemipristis.

[VAfossilguy]

7 minutes ago, ynot said:

Tooth position in the jaw and species of shark. It is a typical back of jaw tooth for a hemipristis.

Thanks! That makes sense now. I have never seen one like that before and I have seen lots of Hemis.  

[MarcoSr]

10 hours ago, Doctor Mud said:

Thanks @MarcoSr if there was an extremely informative button I would click that.

 

Is it true that symphyseal teeth are not lost or replaced like other files?

This is usually a claim for rarity of symphyseal teeth.

 

 

 

I really haven't seen any concrete data on that.  There are replacement teeth in their files just like other tooth positions so they can be lost and replaced.  They are not active (functional) teeth like most of the other first or second row (depends on the shark species) teeth in the jaw.  They are there for spacing to keep the other teeth in the proper jaw position.  So not being used they might not be lost or replaced as often as other tooth positions.  Another reason that they may be rarer is that in a lot of shark species that have these tooth positions (A lot of shark species don't even have them), they are very small, usually much smaller than teeth in the other positions.  Most won't be seen surface collecting because of their small size.

 

Marco Sr.

[MarcoSr]

6 hours ago, ynot said:

Tooth position in the jaw and species of shark. It is a typical back of jaw tooth for a hemipristis.

 

6 hours ago, VAfossilguy said:

What explains the strange form and serration of this tooth? 

 

Like Tony said above it is a function of tooth position in the jaw.  If you want to see more tooth positions of an extant Hemipristis elongatus (Snaggletooth Shark) check out the below link.

 

http://www.thefossilforum.com/index.php?/topic/61407-extant-hemipristis-elongatus-snaggletooth-shark-jaw/#comment-654410

 

 

Marco Sr.

[Paleoc]

Hemipristis does not have symphysial teeth, they have parasymphysials.  True symphysials sit on the symphysis which is the literal center of the jaw.  Hemipristis has rough cartilage in the center of the upper and lower jaw, the parasymphysial teeth sit on either side of that but not actually on center like in Carcharhinus species.

[MarcoSr]

On 7/30/2017 at 7:23 PM, Paleoc said:

Hemipristis does not have symphysial teeth, they have parasymphysials.  True symphysials sit on the symphysis which is the literal center of the jaw.  Hemipristis has rough cartilage in the center of the upper and lower jaw, the parasymphysial teeth sit on either side of that but not actually on center like in Carcharhinus species.

 

The terminology used by shark researchers  for these teeth is not consistent.  Compagno (probably the best known shark researcher) 1988 and a good number of other shark researchers wouldn't agree with you.  You need to look at modern jaws.  What you have said about Carcharinus is inaccurrate.  A lot of the Carcharhinus species have a medial file and two symphysial files just like Hemipristis.  Most researchers use a convention with medial, alternate and symphysial teeth with the medial or alternate teeth in between the symphysial teeth.  Some researchers use a convention with parasymphysial teeth.

 

The below JPEG comes from a page in "Sharks of the Order Carcharhiniformes" by Compagno 1988.  Shown is an upper tooth set of Hemipristis elongatus with the "M" for medial and the "S" for symphysial.  There are numerous other researchers that agree with Compagno on these designations for Hemipristis.  However there is such a terminology inconsistency among researchers that there are other researchers who do not agree even with his anterior, lateral, and posterior designations.

 

 

 

Marco Sr.

[sixgill pete]

On 7/31/2017 at 1:09 AM, MarcoSr said:

 

The terminology used by shark researchers  for these teeth is not consistent.  Compagno (probably the best known shark researcher) 1988 and a good number of other shark researchers wouldn't agree with you.  You need to look at modern jaws.  What you have said about Carcharinus is inaccurrate.  A lot of the Carcharhinus species have a medial file and two symphysial files just like Hemipristis.  Most researchers use a convention with medial, alternate and symphysial teeth with the medial or alternate teeth in between the symphysial teeth.  Some researchers use a convention with parasymphysial teeth.

 

The below JPEG comes from a page in "Sharks of the Order Carcharhiniformes" by Compagno 1988.  Shown is an upper tooth set of Hemipristis elongatus with the "M" for medial and the "S" for symphysial.  There are numerous other researchers that agree with Compagno on these designations for Hemipristis.  However there is such a terminology inconsistency among researchers that there are other researchers who do not agree even with his anterior, lateral, and posterior designations.

 

 

 

Marco Sr.

 

Marco, from what I am reading here, the center, narrow tooth as I have pictures above would actually be considered a medial tooth and not the symphyseal?

[Paleoc]

I need to look at modern jaws???  I only have 3 Hemipristis jaws.  I used to have 4 but I donated one to the museum.  I actually have the jaws rather than just a book (which I have as well).

 

Lets look at the definition of symphysis:

sym·phy·sis

ˈsimfəsəs/

noun

noun: symphysis; plural noun: symphyses

1. 1.

   the process of growing together.
2. 2.

   a place where two bones are closely joined, either forming an immovable joint (as between the pubic bones in the center of the pelvis) or completely fused (as at the midline of the lower jaw).

Origin

late 16th century (sense 2): modern Latin, from Greek sumphusis, from sun- ‘together’ + phusis ‘growth.’

 

Now lets look at a Hemipristis jaw symphysis (upper and lower).  And look Ma, no teeth actually sitting on the joint.  Now most of the time, it looks like it has them because the jaws have been flattened.  They flatten the jaws to make handling and shipping easier (it easier to stack flat jaws) and it makes them wider (i.e. larger) and easier to hang on the wall.  And when they flatten the jaws the teeth next to symphysis lean over (often crossing) and look like they are directly in the mid-line. 

 

 

Now by definition, a symphyisial tooth has to actually sit on the joint and we can see in the images, that is NOT the case.

 

Now let's look at a Carcharhinus jaw, in this case C. leucas.  And we can clearly see that in the lower jaw (the upper is not visible in this image) that a tooth actually sits on the symphysis (joint) on the lower jaw.  (And yes I have several bull shark jaws as well along with about 200 other jaws of about 120 species).

 

 

[Coco]

Hi,

 

Please put again your last pic, we can't see it

 

Coco

[MarcoSr]

8 hours ago, sixgill pete said:

 

Marco, from what I am reading here, the center, narrow tooth as I have pictures above would actually be considered a medial tooth and not the symphyseal?

 

Don

 

If you follow the convention that I do it would be a medial tooth.  In another convention it would be a symphyseal.  The terminology isn't consistent at all. That is what I'm trying to point out.

 

Marco Sr.

 

[sixgill pete]

28 minutes ago, MarcoSr said:

 

Don

 

If you follow the convention that I do it would be a medial tooth.  In another convention it would be a symphyseal.  The terminology isn't consistent at all. That is what I'm trying to point out.

 

Marco Sr.

 

 

I have always referred to them as symphyseal. But, I am always open to change. I will look for an online copy of Campagno and check it out.

 

[MarcoSr]

On 8/5/2017 at 9:20 AM, Paleoc said:

I need to look at modern jaws???  I only have 3 Hemipristis jaws.  I used to have 4 but I donated one to the museum.  I actually have the jaws rather than just a book (which I have as well).

 

Lets look at the definition of symphysis:

sym·phy·sis

ˈsimfəsəs/

noun

noun: symphysis; plural noun: symphyses

1. 1.

   the process of growing together.
2. 2.

   a place where two bones are closely joined, either forming an immovable joint (as between the pubic bones in the center of the pelvis) or completely fused (as at the midline of the lower jaw).

Origin

late 16th century (sense 2): modern Latin, from Greek sumphusis, from sun- ‘together’ + phusis ‘growth.’

 

Now lets look at a Hemipristis jaw symphysis (upper and lower).  And look Ma, no teeth actually sitting on the joint.  Now most of the time, it looks like it has them because the jaws have been flattened.  They flatten the jaws to make handling and shipping easier (it easier to stack flat jaws) and it makes them wider (i.e. larger) and easier to hang on the wall.  And when they flatten the jaws the teeth next to symphysis lean over (often crossing) and look like they are directly in the mid-line. 

 

 

Now by definition, a symphyisial tooth has to actually sit on the joint and we can see in the images, that is NOT the case.

 

Now let's look at a Carcharhinus jaw, in this case C. leucas.  And we can clearly see that in the lower jaw (the upper is not visible in this image) that a tooth actually sits on the symphysis (joint) on the lower jaw.  (And yes I have several bull shark jaws as well along with about 200 other jaws of about 120 species).

 

 

 

 

Your views are extremely narrow.  If you did read books you would see that shark tooth terminology is totally inconsistent.  American and European researchers don’t even agree on the definitions of basic terms like file and row. 

 

I actually have more modern shark jaws in my personal collection than you do.  I’ve posted pictures of at least 16 modern species here on TFF.  If you have as many jaws as you claim, and multiple jaws from the same species, the first thing you should notice is that teeth in the symphysis of the same shark species can vary widely.  Also the total number of teeth in the jaw can vary that is why shark researchers typically show a range.

 

I’ve posted pictures in replies above from one of my five Hemipristis elongatus jaws where you can actually see clearly the teeth in the symphysis.  All five of my jaws have medial files of teeth that run along the jaw midline which has a small toothless space and symphyseal teeth files that are on both sides of the medial files.   The Hemipristis jaw is fairly weak along the midline and that is why a lot of jaws are bent or folded there.   I’m reposting them again.  It is really difficult to tell anything from your pictures.

 

 

 

 

 

I will again cite Compagno 1988 and show with the below image that he clearly feels Hemipristis elongatus have medial and symphysial (symphyseal) tooth files.  Also I would like to point out that the spelling symphysial/symphyseal is not even consistent among researchers never mind the definition.

 

I’ve posted a Hemipristis elongatus jaw showing both medial and symphysial teeth.  I’ve posted evidence that probably the top shark researcher of our time agrees with my position.  I could cite others who also agree.

 

Please just cite one extant shark researcher who claims that Hemipristis do not have medial and symphysial tooth files and have parasymphyseal teeth instead as you claim.  

 

EDIT:

You follow a strict interpretation of shark tooth terminology like symphyseal and parasymphyseal.  I follow a broader interpretation and use shark tooth terminology developed by shark researchers like Applegate and Compagno and others.  Studying extant shark jaws made me better understand the need and rational for some of this terminology.  It is very surprising that with your extensive shark jaw collection that you are not more open to this terminology.  It is very unfortunate that there is so much inconsistency in shark tooth terminology that it becomes difficult to have basic discussions about fossil teeth like presented in this post because of these inconsistencies.

 

Marco Sr.

 

[MarcoSr]

 

7 hours ago, sixgill pete said:

 

I have always referred to them as symphyseal. But, I am always open to change. I will look for an online copy of Campagno and check it out.

 

 

Don

 

Below are definitions/terminology from Compagno 1988 that I follow/use.  Note what he specifically says about Hemipristis.

 

 

 

 

Marco Sr.

[doushantuo]

APPL86hetero

[MarcoSr]

4 hours ago, doushantuo said:

APPL86hetero

 

Thank you for posting the Applegate 1965 paper.  In "Sharks of the Order Carcharhiniformes"  1988, Compagno used this paper as a basis for his tooth terminology.

 

Marco Sr.

[siteseer]

On July 28, 2017 at 4:26 AM, MarcoSr said:

 

I really haven't seen any concrete data on that.  There are replacement teeth in their files just like other tooth positions so they can be lost and replaced.  They are not active (functional) teeth like most of the other first or second row (depends on the shark species) teeth in the jaw.  They are there for spacing to keep the other teeth in the proper jaw position.  So not being used they might not be lost or replaced as often as other tooth positions.  Another reason that they may be rarer is that in a lot of shark species that have these tooth positions (A lot of shark species don't even have them), they are very small, usually much smaller than teeth in the other positions.  Most won't be seen surface collecting because of their small size.

 

Marco Sr.

 

Hi Marco Sr.,

 

Yet another reason why we don't often see symphyseal/parasyphyseal teeth especially the lower ones of Hemipristis is that the teeth are also rather fragile - long thin crowns and small roots.  I have maybe two specimens total in my collection and the one I can think of is missing most of the root.  Teeth in these positions are in the very slow process of being "phased out" taking on a reduced morphology as they become less functional, a dentition becoming more efficient (doing the same job with less teeth).  An isolated crown of one of these teeth would be difficult to recognize, and by the time the root is mostly gone, it's wearing down or cracking.

 

Jess

 

 

[MarcoSr]

5 hours ago, siteseer said:

 

Hi Marco Sr.,

 

Yet another reason why we don't often see symphyseal/parasyphyseal teeth especially the lower ones of Hemipristis is that the teeth are also rather fragile - long thin crowns and small roots.  I have maybe two specimens total in my collection and the one I can think of is missing most of the root.  Teeth in these positions are in the very slow process of being "phased out" taking on a reduced morphology as they become less functional, a dentition becoming more efficient (doing the same job with less teeth).  An isolated crown of one of these teeth would be difficult to recognize and by the time the root is mostly gone it's wearing down or cracking.

 

Jess

 

 

 

Jess

 

They are very fragile.  Hemipristis  elongatus normally have two files of medial teeth (Compagno 1988), one file on either side of a small toothless area in the midline of the jaw. I was only seeing one file in the jaw that I took/showed pictures of in this post.  It may be that the second file is there but because of the twisting of the files it may be difficult to pick out.  It could also be that this specific shark has already lost that file because it really didn't have use.  Also I do see a lot of differences in morphology/number of teeth in the symphysis area of extant shark jaws of the same species like in the genus Carcharhinus.  I should have used another of my Hempristis jaws for my pictures that better showed the two medial files and toothless space but the twisting of the files/teeth in this jaw allowed me to show the tooth features of the medial teeth which you really couldn't see in my other jaws.

 

Marco Sr.