Paleontica Community

The teeth of me is almost 3 centimetres and has also this strange shape. Can you tell me what this is ?

Greets,

Nothing easier than this:

Hexanchus gigas/griseus
Upper jaw posterio-lateral

Kind regards


Stephan


Btw: 3cm is too large for nakamurai at all...

Ik heb deze enkel onder hexanchidae,Zijn wel erg kleine tandjes,je ziet nog net het mm papier onderaan.
Dat wit op de éérste foto is een pasta om het ding beter in evenwicht te kleven

Theo schreef:
Ik heb deze enkel onder hexanchidae

And right you are ( according to me;D ).
Trade??

Greetings


Stephan

[Bewerkt door Steph op 16-12-2008 om 10:15 NL]

Steph schreef:
YOu can see the difference between griseus and nakamurai on your own pic: nakamurai, despites being really much smaller, has a long, curved primary cusp. This is also thinner than the one of the gigas/ griseus-line.

For me, your teeth are very typical upper Hexanchus gigas. Look at your pics, and look on the ( very bad ) pic of a griseus-jaw on elasmo, and search on google, and look on my pic. Your teeth show typical gigas-features...
[Bewerkt door Steph op 15-12-2008 om 20:12 NL]

Hi Steph,

I would tentatively agree with reference to your sources. However consulting Herman & Hovenstadt 1994 questionmarks seem legit.

Pepijn

ps. depicted are 8th and 9th uppers of H.griseus, H.nakamurai and H.vitulus

isis schreef:

However consulting Herman & Hovenstadt 1994 questionmarks seem legit.

The paper is not familiar to me, do you have any source where I could get a pdf-data?

isis schreef:

ps. depicted are 8th and 9th uppers of H.griseus, H.nakamurai and H.vitulus

Could you outline to me what the difference between H. vitulus and nakamurai is? For me they are synonym and refer to the same shark ( Bigeye sixgill shark )?!
I would like to learn something new concerning this...


Anyway, I am still of the opinion that we are talking about "normal" H. gigas/griseus teeth. I don´t really see any reason for declaring that those teeth are H. nakamurai.
If someone here could tell me why you think so, it is not really clear to me yet...

Btw, of course I already heard about the theory that there are 2 lineages in fossil record of Hexanchus, the griseus-line and the vitulus-line, but never saw a proof for that yet... I remain curious!


Stephan

God,

interessant allemaal.
Ook heel mooi, dat tandje van Theo.
Bedankt voor de info iedereen.

gr. robin

He Robin,

mooie tandjes,
heb ooit eens een artikel van internet gehaald dat je eens moet lezen:
"biometric analysis of the teeth of fossil and recent hexanchid sharks" Adnet s. 2006
acta Palaeontologica Polonica 51(3):477-488.

misschien heb je hier iets aan.

groeten,
wally

Steph schreef:
The paper is not familiar to me, do you have any source where I could get a pdf-data?

If you sent me an e-mail I can provide you (and ayone else interested) with a copy.

Steph schreef:
Could you outline to me what the difference between H. vitulus and nakamurai is? For me they are synonym and refer to the same shark ( Bigeye sixgill shark )?!

I can't. I made reference to Herman et. al. who depicted dentitions as separate species and suggested odontological proof for that, however did not draw nomenclatorially conclusions....(?) I know Compagno et. al (2005; Sharks of the world. etc) agrees with you both are synonym. Unfortunately I myself have to follow other's and their opinions since my encounters with these magnificent sixgilled are non-existent (I hope to dive with them one day though).
Stephan[/quote]

Steph schreef:
Anyway, I am still of the opinion that we are talking about "normal" H. gigas/griseus teeth. I don´t really see any reason for declaring that those teeth are H. nakamurai.
If someone here could tell me why you think so, it is not really clear to me yet...
Stephan

As I said: I tentatively agree. However you could also turn this argument around.... Proof the depicted upper laterals by Binbinneke are not H.nakamurai (you know what they say about size, right?). So: questionmarks are legit.

Steph schreef:
Btw, of course I already heard about the theory that there are 2 lineages in fossil record of Hexanchus, the griseus-line and the vitulus-line, but never saw a proof for that yet... I remain curious!
Stephan

Wally gave us an excellent tip actually (I forgot all about this article). Adnet may shed more light for you on grisiform and vutuliform groups. In fact this article states the dificulties separating species odontologicaly (as done with fossil finds) due to ontogenetic differences. If you (or aynone else) want I can sent this article as well.

---

Now, I have a question as well. You wrote earlier the dentition of H.griseus on the elasmo.com is very poorly depicted. I therefor assume you have very well depicted dentitions of H.griseus (or you have a dentition of which you can make pictures of). Would you be so kind to share with us?

isis schreef:

Unfortunately I myself have to follow other's and their opinions since my encounters with these magnificent sixgilled are non-existent (I hope to dive with them one day though).
Stephan

Yes I see and understand, but although I am neither a scientist nor anything else like that, but only a young maybe naive collector ( with a fable for watching things, judging about them and discussing that ), I am not really following any other opinions, neither the ones of scientist nor the ones of collectors, at least not as long as I can´t follow the argumentation. Maybe if I read the article, things may change for me. Who knows?

isis schreef:

As I said: I tentatively agree. However you could also turn this argument around.... Proof the depicted upper laterals by Binbinneke are not H.nakamurai (you know what they say about size, right?). So: questionmarks are legit.

They alway are. I don´t say I can´t be wrong. All just my personal observsations and subjective arguments.
I once had a discussion with another collector of Hexanchidae from Germany, and he showed me a lot of Morrocon Hexanchus teeth whith morphological differences. However, for me those differences are not strong and explicit enough to divide the teeth into two specimen. Surely inner-species ( word right? don´t know it in English, and can´t find it either ) variance must be involved in the discussion.
And I can´t follow a straight line through fossil record that allows the theory of two lineages for me...
Anyway, I find it kind of strange that we are alway talking about upper teeth, which are not always easy to distinguish ( sometimes even the determination of the genus is problematical ). I have seen no fossil lower tooth which looks like a nakamurai yet.

Anyway, looking at your second and third pic and at Robin´s third pic, I surely see why you think about the possibility of nakamurai.

isis schreef:

Wally gave us an excellent tip actually (I forgot all about this article). Adnet may shed more light for you on grisiform and vutuliform groups. In fact this article states the dificulties separating species odontologicaly (as done with fossil finds) due to ontogenetic differences. If you (or aynone else) want I can sent this article as well.

I know Wally´s article, but as I said I don´t know the one you mentioned, you´ll get mail concerning this.

isis schreef:
Now, I have a question as well. You wrote earlier the dentition of H.griseus on the elasmo.com is very poorly depicted. I therefor assume you have very well depicted dentitions of H.griseus (or you have a dentition of which you can make pictures of). Would you be so kind to share with us?

Haha, you got me. Surely a point for you. I have to admit that I don´t own a jaw myself ( several reasons for that ), which might or might not change in the future.
However, I compared all my Hexanchid teeth to several jaws owned by friends of mine. On Sunday one will visit me, maybe I can ask him to bring his jaws and I´ll make some photos...

For pictures from the net: there are quite a lot out there, googling and looking on shark- and sharkfossil-websites always helps. There are also several commercial websites for sharkteeth who offer Hexanchid jaws, which are often well photographed. I have saved a few/ the best ones of them on my computer, but please understand I won´t post them here, simply due to the copyright ( should be in my and the forum-leader´s interest... ).
But do you disagree that the pictures from elasmo aren´t optimal? I appreciate elasmo really much, but the pictures of the Hexanchus jaw I find rather poor...

Best regards


Stephan

[Bewerkt door Steph op 17-12-2008 om 18:07 NL]