On Associated Teeth

[JimB88]

I had mentioned in my latest hunt report that I had found a large boulder with 5+ teeth in a six inch square area (two were on the surface of the boulder and the others were just below them, around 1/4 inch deep.) They all seem to be from a small Helodus type shark. Could they be associated with one another? Or is it just coincidence that they fell/were collecting in the same spot do to turbation sorting the material out by size before fossilization? Could a fossil 1/4 inch deeper in the rock be from the same animal? Or would one need to know how quickly the lime mud was accumulating? It just brought up many questions (like should I keep the teeth together or can I remove them from the matrix?)

[bear-dog]

Even if they are associated teeth,I would clean them up in the matrix.Just my 2 cents worth.

[Auspex]

They are "associated" in the matrix; whether they are remains from the same individual might be hard to tell for sure.

What seems to be going for the concept is that they are rare teeth, and a close concentration is an unusual find. (Then again, there is another way for stuff of the same size & density to get sorted by moving water).

[Tony Eaton]

Wow, that sounds like an awesome find.

I've seen some Paleozoic rock where very narrow bands will concentrate similar teeth. If you see signs that this is a concentrated layer that might point to the sort of winnowing that you suspect. However, I don't think Helodus shed teeth?

It took a lot of digging but I found a publication showing a Helodus dentation.

"The Phylogeny of the Chimaeroids"

Compared to similar "sharks" there isn't much heterodonty with Helodus and there are a lot more teeth than the typical bradyodont, I guess making it a bit harder to say if this was an associated dentation.

[JimB88]

Wow, that sounds like an awesome find.

I've seen some Paleozoic rock where very narrow bands will concentrate similar teeth. If you see signs that this is a concentrated layer that might point to the sort of winnowing that you suspect. However, I don't think Helodus shed teeth?

It took a lot of digging but I found a publication showing a Helodus dentation.

"The Phylogeny of the Chimaeroids"

Compared to similar "sharks" there isn't much heterodonty with Helodus and there are a lot more teeth than the typical bradyodont, I guess making it a bit harder to say if this was an associated dentation.

That is unusual as Helodus is a hybodont shark not closely related to the chimaeroids. As far as Helodus shedding teeth according to this paper

The first Devonian holocephalian tooth from Poland

it is believed that they did. Though after looking at the pics in this paper I wonder if Ive actually found a mass of Psephodus teeth as they look similar to those shown (though the Psephodus Ive found here look much different...hmmmm. )I cant seem to get an expert on Bradyodonts to answer my email inquiries either so there is still some doubt as to what I am finding (the Cladodus and Petalodus are obvious though.)

[Tony Eaton]

That is unusual as Helodus is a hybodont shark not closely related to the chimaeroids. As far as Helodus shedding teeth according to this paper

The first Devonian holocephalian tooth from Poland

it is believed that they did. Though after looking at the pics in this paper I wonder if Ive actually found a mass of Psephodus teeth as they look similar to those shown (though the Psephodus Ive found here look much different...hmmmm. )I cant seem to get an expert on Bradyodonts to answer my email inquiries either so there is still some doubt as to what I am finding (the Cladodus and Petalodus are obvious though.)

Thanks for the link to that article. I see that there is a "conveyor belt" of replacement teeth for Helodus in "Figure B" and "figure C" is interesting too.

Here is the image from the doc I cited before that I found interesting since it shows some detail of Helodus dentation which does't seem to match figure B above, however from the text.

The Phylogeny of the Chimaeroids

http://rstb.royalsocietypublishing.org/content/249/757/101.short

"The dentition consists of eight or nine series of teeth in each ramus of the jaws, where the teeth are largest, one or two series of teeth are more or less completely fused into the tooth plate ('Pleurodus') which is divided by constrictions into cusps corresponding with the separate teeth of nieghbouring series. At the symphysis of the lower jaw a biscupid tooth ('Diclitodus') is sometimes present, evidently equivalent to members of the most medial paired series of teeth. The crowns of the teeth consist of typical tubular dentine and are without tritors."

Edited April 21, 2011 by Tony Eaton

[JimB88]

Thanks for the link to that article. I see that there is a "conveyor belt" of replacement teeth for Helodus in "Figure B" and "figure C" is interesting too.

Here is the image from the doc I cited before that I found interesting since it shows some detail of Helodus dentation which does't seem to match figure B above, however from the text.

The Phylogeny of the Chimaeroids

http://rstb.royalsocietypublishing.org/content/249/757/101.short

"The dentition consists of eight or nine series of teeth in each ramus of the jaws, where the teeth are largest, one or two series of teeth are more or less completely fused into the tooth plate ('Pleurodus') which is divided by constrictions into cusps corresponding with the separate teeth of nieghbouring series. At the symphysis of the lower jaw a biscupid tooth ('Diclitodus') is sometimes present, evidently equivalent to members of the most medial paired series of teeth. The crowns of the teeth consist of typical tubular dentine and are without tritors."

thanks for that too! Ive been looking for something that illustrates their dentition.

[Nandomas]

Jim , I do not know if the teeth are associated or not, but you did really well. Enjoy you teeth

Cheers

Nando