Pathologic I.d. + Possible Ray Barbs?

[oldlabelerman]

Took a day off and doing some organizing---Man I need more ROOM! The collection is growing but the space has not. Anyway---I have I believe two pathological but not sure as to what shark they are. The first I think is a Meg because of the cool bourlette. The tooth itself is perfect--some of the root has broke off. The center part is fully serrated with the unusual cusps at each end,. The second tooth---maybe a Lemon? It has a nice sharp downward curve at the tip--no serrations but has cusps at both ends. And finally, I believe are perhaps barbs from a Ray?

[Harry Pristis]

For comparison:

[oldlabelerman]

For comparison:

Thanks Harry, I was thinking maybe catfish but thought they were too big.

[Al Dente]

The first tooth is Galeocerdo.

[Harry Pristis]

The first tooth is Galeocerdo.

Don't the bourlette and the prominent nutrient groove make it unlikely that this is Galeocerdo ?

[Al Dente]

Don't the bourlette and the prominent nutrient groove make it unlikely that this is Galeocerdo ?

Most of the Carcharhiniformes have a nutrient groove including Galeocerdo. A dental band is common to many species of shark. I should add that this is a symphysial tooth.

[siteseer]

Yeah, that's a Galeocerdo symphyseal all the way - G. cuvier from the size of it. I have seen modern teeth with the groove and dental band.

Most of the Carcharhiniformes have a nutrient groove including Galeocerdo. A dental band is common to many species of shark. I should add that this is a symphysial tooth.

[Harry Pristis]

Most of the Carcharhiniformes have a nutrient groove including Galeocerdo. A dental band is common to many species of shark. I should add that this is a symphysial tooth.

Goodness! I guess we could argue "prominent" versus "relatively broad and shallow" (Kent, 1994), but you seem to believe that one nutrient groove is as good as the next.

Are you equating "dental band" with "bourlette"? Many sharks have a "dental groove," according to Kent's terminology; but, he reserves the term "bourlette" for Carcharocles. Perhaps you are using someone else's terminology.

The tooth here doesn't resemble at all the Galeocerdo symphysial teeth presented in Kent's book. Perhaps there are subscribers here who can check their modern specimen jaws for similar teeth.

Show us your evidence, Al and Jess.

Edited May 16, 2011 by Harry Pristis

[siteseer]

Harry,

I'll try to get a photo tomorrow. I have seen G. cuvier teeth with a nutrient groove ("rather shallow") and have seen one or two with just an apparent foramen and also some with no sign of either. It appears to be a feature easily eroded because I have seen teeth with which it is unclear.

Kent (1994: p.91) defines a "bourlette" as a "broad basal groove covered with a thick layer of pallial dentine; particularly prominent on teeth in the genus Carcharocles." Welton and Farish (1993: p. 183) defined a "dental band" as "a narrow, smooth, enameloid-free band that occurs at the crown foot of a tooth." Kent was specific about the dentine type while Welton and Farish were not so that might be the distinction. Otherwise, it does appear that they are all referring to the same tooth character (a boundary zone between the crown and root - slightly depressed relative to the root and duller in preservation relative to the crown enameloid). The bourlette and dental band appear to be less resistant to erosion than the crown and about as much as the root.

Unfortunately, Purdy et al. (2001), the Lee Creek volume covering fishes, reptiles and birds, neglected to discuss whether the teeth had a pore or a groove or a dental band and Figure 51 (p. 148) showing a composite dentition of "Galeocerdo cf. G. cuvier" offers no clear evidence either way. It is possible that Pliocene teeth that resemble G. cuvier could be a species distinct from modern G. cuvier (a topic of discussion in Purdy et al. (2001:p. 147).

Kent shows the limitations of line drawings. Some of the teeth in the dentitions pages especially look simplified. His cuvier symphyseals do not resemble specimens I have examined though there is a range in variation from symmetrical to asymmetrical (less so than the anteriors) - see Johnson, 1978: p. 130; Cappetta, 1986 (p. 66 though this is also a drawing). There is also mention here (see page 23):

http://docs.google.com/viewer?a=v&q=cache:5NX4x4iKd9cJ:www-alt.naturkundemuseum-bw.de/stuttgart/pdf/b_pdf/B283.pdf+galeocerdo+cuvier+lower+symphyseal&hl=en&gl=us&pid=bl&srcid=ADGEESgge0gayLOBE31ACWd_67pYM2OzDxsMRu5QchymsaSGYD-DzMHBUvvTpojw3J6PRBzWDzPM_lCViDy9KClkZqjGDJhArrwKA_KVNDvNJ04NNcfXM_yrico-NvR6F69sesIYkUwb&sig=AHIEtbRTEr4z2SaZnWEWIxh6hDSA2-znJg

Jess

Cappetta, H. 1986.

Types dentaires adaptifs chez les selaciens actuels et post-paleozoiques. Palaeovertebrata. 16(2):57-76.

Johnson, R.H. 1978.

Sharks of Polynesia. Les Editions du pacifique. (I have also seen this book by a different publisher).

Goodness! I guess we could argue "prominent" versus "relatively broad and shallow" (Kent, 1994), but you seem to believe that one nutrient groove is as good as the next.

Are you equating "dental band" with "bourlette"? Many sharks have a "dental groove," according to Kent's terminology; but, he reserves the term "bourlette" for Carcharocles. Perhaps you are using someone else's terminology.

The tooth here doesn't resemble at all the Galeocerdo symphysial teeth presented in Kent's book. Perhaps there are subscribers here who can check their modern specimen jaws for similar teeth.

Show us your evidence, Al and Jess.

Edited May 16, 2011 by siteseer

[Al Dente]

Goodness! I guess we could argue "prominent" versus "relatively broad and shallow" (Kent, 1994), but you seem to believe that one nutrient groove is as good as the next.

Are you equating "dental band" with "bourlette"? Many sharks have a "dental groove," according to Kent's terminology; but, he reserves the term "bourlette" for Carcharocles. Perhaps you are using someone else's terminology.

The tooth here doesn't resemble at all the Galeocerdo symphysial teeth presented in Kent's book. Perhaps there are subscribers here who can check their modern specimen jaws for similar teeth.

Show us your evidence, Al and Jess.

The identification of this tooth can be made without looking at the dental band (bourlette?) or nutrient groove. I know of only two genera that have the complex serrations that this tooth has- Squalicorax and Galeocerdo. Since Squalicorax is Cretaceous and this tooth is from Florida, thenGaleocerdo is the only option left.

Here's a web site that has a variety of Galeocerdo teeth including a similar symphysial half way down the page. Notice how the nutrient grooves in these teeth vary in depth and how the dental band is well defined in some teeth and eroded off in others: http://www.fossilguy.../galeocerdo.htm

[bierk]

I would suggest that what is being called 'bourlette' on this one tooth may just be some very minor enamel erosion. I've seen it on many teeth from the Peace. The enamel gets in effect polished off and not chipped up like one might think. I would definitely say this is an uncommon tooth position Galeocerdo cuvier.

[Harry Pristis]

I'm afraid that the three of you are seeing what you want to see, not what is there. You are not even listening to your own evidence.

First thing to do is to read what 'oldlabelerman' wrote: "The first I think is a Meg because of the cool bourlette. The tooth itself is perfect--some of the root has broke off. The center part is fully serrated with the unusual cusps at each end".

Second thing to do is to read again Jess' explanation: "Kent (1994: p.91) defines a 'bourlette' as a "broad basal groove covered with a thick layer of pallial dentine; particularly prominent on teeth in the genus Carcharocles.' Welton and Farish (1993: p. 183) defined a 'dental band' as 'a narrow, smooth, enameloid-free band that occurs at the crown foot of a tooth.' Kent was specific about the dentine type while Welton and Farish were not so that might be the distinction."

In other words, "bourlette" = broad, thick layer of dentine while "dental band" = narrow, enameloid-free band. That is the distinction.

The arguments that Kent's line-drawings are inadequate or that the Mio-Pliocene G. cuvier might be a species different from the modern both seem to me to be overreaching.

Al makes the a priori argument that the "the complex serrations that this tooth has" are normal; therefore, they are diagnostic. Relying on his unproven assumption, he argues that the tooth must be G. cuvier.

But, I argue, if the tooth is normal, and it is a tiger shark, how can the crown be fully serrated?

Al dismisses the two features (bourlette and nutrient groove) less-likely to be affected in a tooth pathology in favor of the feature perhaps most likely to be affected (complex serrations).

C'mon, guys! You can make stronger arguments than those.

[bierk]

I'm afraid that the three of you are seeing what you want to see, not what is there. You are not even listening to your own evidence.

First thing to do is to read what 'oldlabelerman' wrote: "The first I think is a Meg because of the cool bourlette. The tooth itself is perfect--some of the root has broke off. The center part is fully serrated with the unusual cusps at each end".

Second thing to do is to read again Jess' explanation: "Kent (1994: p.91) defines a 'bourlette' as a "broad basal groove covered with a thick layer of pallial dentine; particularly prominent on teeth in the genus Carcharocles.' Welton and Farish (1993: p. 183) defined a 'dental band' as 'a narrow, smooth, enameloid-free band that occurs at the crown foot of a tooth.' Kent was specific about the dentine type while Welton and Farish were not so that might be the distinction."

In other words, "bourlette" = broad, thick layer of dentine while "dental band" = narrow, enameloid-free band. That is the distinction.

The arguments that Kent's line-drawings are inadequate or that the Mio-Pliocene G. cuvier might be a species different from the modern both seem to me to be overreaching.

Al makes the a priori argument that the "the complex serrations that this tooth has" are normal; therefore, they are diagnostic. Relying on his unproven assumption, he argues that the tooth must be G. cuvier.

But, I argue, if the tooth is normal, and it is a tiger shark, how can the crown be fully serrated?

Al dismisses the two features (bourlette and nutrient groove) less-likely to be affected in a tooth pathology in favor of the feature perhaps most likely to be affected (complex serrations).

C'mon, guys! You can make stronger arguments than those.

I appreciate the comment to make stronger arguments! But, I don't see any way this can be anything but Galeocerdo. I'm not seeing anything suggesting an ID other than Galeocerdo. I also do not see what I believe is missing: bourlette. All I see there is erosion of the enamel, period.

Regarding the serrations going up the crown...so what? All my tiger shark teeth are serrated from tip to root up and down both sides of the tooth, period. The 'scalloping' of the serrations as it appears off the main center cusp of this tooth are the same as every other G. cuvier I have, and not like any other tooth I've ever found. I don't see any other options based on the two photos provided. I don't see any pathology affecting serrations, nor root on this tooth. If there are things I'm not seeing or commenting on, please fire away as I always want to learn more than I currently know.

[oldlabelerman]

I appreciate the comment to make stronger arguments! But, I don't see any way this can be anything but Galeocerdo. I'm not seeing anything suggesting an ID other than Galeocerdo. I also do not see what I believe is missing: bourlette. All I see there is erosion of the enamel, period.

Regarding the serrations going up the crown...so what? All my tiger shark teeth are serrated from tip to root up and down both sides of the tooth, period. The 'scalloping' of the serrations as it appears off the main center cusp of this tooth are the same as every other G. cuvier I have, and not like any other tooth I've ever found. I don't see any other options based on the two photos provided. I don't see any pathology affecting serrations, nor root on this tooth. If there are things I'm not seeing or commenting on, please fire away as I always want to learn more than I currently know.

I'm way out of my expertise here but am only submitting additional info to hopefully assist in this. As I have the tooth to physically examine--I have a small advantage to offset my lack of expertise. The "Bourlette" to me shows absolutely no sign of erosion. It is , in fact, very shiny and extremely smooth. Running my thumb nail up and down the border of the tooth and "Bourlette" I can only barely feel a tiny difference to suggest the presence of the border. If erosion produced the "Bourlette" it did a magnificent job by producing such a perfect pattern. Don't you think? I hope this helps.

[bierk]

I'm way out of my expertise here but am only submitting additional info to hopefully assist in this. As I have the tooth to physically examine--I have a small advantage to offset my lack of expertise. The "Bourlette" to me shows absolutely no sign of erosion. It is , in fact, very shiny and extremely smooth. Running my thumb nail up and down the border of the tooth and "Bourlette" I can only barely feel a tiny difference to suggest the presence of the border. If erosion produced the "Bourlette" it did a magnificent job by producing such a perfect pattern. Don't you think? I hope this helps.

I've got a G. cuvier tooth from the Peace that looks like that...it might seem to have bourlette but it is just a smoothing of the enamel/root intersection. But it is undoubtedly a tiger shark despite how mine is.

I'd love to examine this tooth in person, it is very cool, regardless of what it is. You've been on a rampage lately and I applaud that!

[oldlabelerman]

I've got a G. cuvier tooth from the Peace that looks like that...it might seem to have bourlette but it is just a smoothing of the enamel/root intersection. But it is undoubtedly a tiger shark despite how mine is.

I'd love to examine this tooth in person, it is very cool, regardless of what it is. You've been on a rampage lately and I applaud that!

Having just started Dec.2010, I guess I'm having beginners luck. That and I got lucky with permission from a land owner [210 acres with "my" creek as it's border] for access. It's all behind locked gates. Then I hit "Honey Hole" after another. If your down this way, would be glad to take you in. It's a strange creek--very little gravel and what I find is shallow-1 to 2 feet on average. I hit big and go back the next day to nothing---strange.

[Harry Pristis]

I'm way out of my expertise here but am only submitting additional info to hopefully assist in this. As I have the tooth to physically examine--I have a small advantage to offset my lack of expertise. The "Bourlette" to me shows absolutely no sign of erosion. It is , in fact, very shiny and extremely smooth. Running my thumb nail up and down the border of the tooth and "Bourlette" I can only barely feel a tiny difference to suggest the presence of the border. If erosion produced the "Bourlette" it did a magnificent job by producing such a perfect pattern. Don't you think? I hope this helps.

Okay, 'bierk' got me on the serrations -- G. cuvier does have very fine serrations on the mesial cusp tip.

But, I argue, if the tooth is normal, and it is a tiger shark, how can the crown be fully serrated?

The question then is how fine are the serrations on this tooth? (I cannot make out any serrations in your images, and I assumed that's because the images are a bit fuzzy.) Compare these serrations to other tiger shark teeth in your collection.

And, 'bierk', how about an image of the similar G.cuvier tooth that you have.

I've got a G. cuvier tooth from the Peace that looks like that...it might seem to have bourlette but it is just a smoothing of the enamel/root intersection. But it is undoubtedly a tiger shark despite how mine is.

[bierk]

Okay, 'bierk' got me on the serrations -- G. cuvier does have very fine serrations on the mesial cusp tip.

The question then is how fine are the serrations on this tooth? (I cannot make out any serrations in your images, and I assumed that's because the images are a bit fuzzy.) Compare these serrations to other tiger shark teeth in your collection.

And, 'bierk', how about an image of the similar G.cuvier tooth that you have.

I'll see what I can do on the image of the tooth I mentioned. Just keep in mind I brought it up due to a similarity in the 'bourlette' that has been discussed and NOT because it is the same position in the mouth by any means. I'm at work until about 6pm so once I get home I'll see if I can dig up that tooth in the G. cuvier drawer.

[cowsharks]

I have one of these teeth from Lee Creek and it looks nearly identical. I don't have a pic handy of it at the moment, but I do have a pic of one my friend found at Lee Creek some years ago. We thought these teeth were also a type of Tiger shark (aduncus) symphyseal, at least at the time we found them. However, I have a couple modern tiger shark jaws, and the symphyseals don't look like these fossil teeth. The fact that these fossil specimens have serrated crowns does not discount them from being tigers since tiger shark teeth have serrated crowns. I also considered this type of tooth position to be from a Carcharhinus of some sort, which I think is a possibility. Due to the bilateral symmetry of these specimens, it seems logical to think that they are symphyseal (or medial) tooth positions. However, last year while I was at the Aurora fossil museum, I took some pictures of the various modern jaws they have hanging on the one wall. In particular, I noticed that one of the large Carcharhinid jaws (Bull or Dusky I don't remember) had a tooth position that looked very similar to these fossil specimens we're discussing, but the tooth position was near the posterior end of the jaw, which didn't make sense. So, I'm not totally sold on these teeth being from a Tiger shark until I have done a bit more research on the Carcharhinus jaws.

Daryl S.

[oldlabelerman]

I have one of these teeth from Lee Creek and it looks nearly identical. I don't have a pic handy of it at the moment, but I do have a pic of one my friend found at Lee Creek some years ago. We thought these teeth were also a type of Tiger shark (aduncus) symphyseal, at least at the time we found them. However, I have a couple modern tiger shark jaws, and the symphyseals don't look like these fossil teeth. The fact that these fossil specimens have serrated crowns does not discount them from being tigers since tiger shark teeth have serrated crowns. I also considered this type of tooth position to be from a Carcharhinus of some sort, which I think is a possibility. Due to the bilateral symmetry of these specimens, it seems logical to think that they are symphyseal (or medial) tooth positions. However, last year while I was at the Aurora fossil museum, I took some pictures of the various modern jaws they have hanging on the one wall. In particular, I noticed that one of the large Carcharhinid jaws (Bull or Dusky I don't remember) had a tooth position that looked very similar to these fossil specimens we're discussing, but the tooth position was near the posterior end of the jaw, which didn't make sense. So, I'm not totally sold on these teeth being from a Tiger shark until I have done a bit more research on the Carcharhinus jaws.

Daryl S.

I hope these will help

[oldlabelerman]

I hope these will help

Sorry, forgot to include a better shot of the "Bourlette"

[Al Dente]

Here are some excerps from Applegate's Phyletic Studies; Part 1; Tiger sharks

A general discussion of tiger shark teeth:

On the inner face in the center of the root, there is a root furrow that posses a simple single root canal.

The crown is usually strongly curved toward the corner of the mouth, except for symmetrical medials.

The larger serrations of the upper portions of the shelf and the central portion of the crown bare small secondary serrae.

[Paleoc]

I'm afraid that the three of you are seeing what you want to see, not what is there. You are not even listening to your own evidence.

First thing to do is to read what 'oldlabelerman' wrote: "The first I think is a Meg because of the cool bourlette. The tooth itself is perfect--some of the root has broke off. The center part is fully serrated with the unusual cusps at each end".

Second thing to do is to read again Jess' explanation: "Kent (1994: p.91) defines a 'bourlette' as a "broad basal groove covered with a thick layer of pallial dentine; particularly prominent on teeth in the genus Carcharocles.' Welton and Farish (1993: p. 183) defined a 'dental band' as 'a narrow, smooth, enameloid-free band that occurs at the crown foot of a tooth.' Kent was specific about the dentine type while Welton and Farish were not so that might be the distinction."

In other words, "bourlette" = broad, thick layer of dentine while "dental band" = narrow, enameloid-free band. That is the distinction.

The arguments that Kent's line-drawings are inadequate or that the Mio-Pliocene G. cuvier might be a species different from the modern both seem to me to be overreaching.

Al makes the a priori argument that the "the complex serrations that this tooth has" are normal; therefore, they are diagnostic. Relying on his unproven assumption, he argues that the tooth must be G. cuvier.

But, I argue, if the tooth is normal, and it is a tiger shark, how can the crown be fully serrated?

Al dismisses the two features (bourlette and nutrient groove) less-likely to be affected in a tooth pathology in favor of the feature perhaps most likely to be affected (complex serrations).

C'mon, guys! You can make stronger arguments than those.

Ok, I hope pictures are enough evidence for you. Here is a Lee Creek tooth and a modern tooth, Note the fully serrate central cusp, the complex shoulder serrations (this tooth shoulders are somewhat damaged but I can supply images of plenty of other teeth on request), the nutritive groove and the bourlette. I have added modern Carcharhinus leucas for comparison. Now which of these features are diagnostic? Both species teeth are fully serrate up to the medial cusp tip. Both species have prominent bourlettes. Both have a nutritive groove (the tiger's "tend" to be broader but I would not say diagnostic). The tiger shark has complex serrations, The bull shark does not.

[Harry Pristis]

Good job, 'Paleoc'! Of course! Images are the best convincers. (And, good images they are!)

Looks like this tooth may be a tiger shark after all.

Thanks to all who participated.

[Fossildude19]

Indeed, thanks to all who participated.

I was following this with great interest, and have learned some things.

Thanks again.

Regards,