I Would Just Like To Say...

[markm]

That is a very helpful diagram. I have personally thought of the whorl as a prey- trapping mechanism and not as a cutting or slicing device. Crushing is out of the question. Think of this whorl as mounted on the meckelian cartilage of the lower jaw, and the palatoquadrate ( upper jaw) as a sort of " strike plate" to hold prey in place. The ingestion of prey in an aquatic environment requires sudden generation of negative pressure (jaw opening) and ingestion of the prey item. If it is too large to swallow whole, it needs to be held in place until another cycle of negative pressure can be generated. The whorl would trap the prey at this moment, perhaps with mortal injury, until the jaw could be opened again.

This would be supported bu the fact that the teeth are almost never worn down in these whorls, an unlikely finding if they were impaling hard-bodied prey

[markm]

Now, permian experts, please give me a list of potential prey items : )

[Jesse]

Excellent post markm! Only thing I would add is that there are small shingle like teeth lining the palatoquadrate and with the serrations found on some of these teeth they were definitely slicing things.

As for prey I think they were almost exclusively eating soft bodied cephalopods. There are occasional scratches found on the sides of teeth in places that could indicate that they were pulling nautiloids from their shells. There were plenty of these swimming around back then and they got pretty big.

[markm]

Serrations don't always slice, they may be locking the prey in place instead. Like a barb on a fishing hook. Regardless, Cephalopoda are the likely target, I agree! How about helico as an expert at attacking the body/shell interface of a partially exposed cephalopod?

This is fun! I am thrilled that experts like you are pursuing these Paleozoic sharks. What are your Edestus theories?

[Jesse]

Serrations don't always slice, they may be locking the prey in place instead. Like a barb on a fishing hook. Regardless, Cephalopoda are the likely target, I agree! How about helico as an expert at attacking the body/shell interface of a partially exposed cephalopod?

This is fun! I am thrilled that experts like you are pursuing these Paleozoic sharks. What are your Edestus theories?

That's where I was going with the scratches on the sides of the teeth. They aren't very common though, if they were frequently pulling cephalopods from their shell I think there would be more than a couple of scratches per specimen.

The serrations are interesting. As juveniles they don't have serrated teeth, they only start getting serrations after tooth number 70 or so. And some of the serrations get fairly nasty looking.

Edestids are a horse of a completely different color! I think that Edestids and Helicoprion are definitely related forms, but I haven't invested a whole lot of energy on them yet, they may be my next project! There are a large number of sharks in the Paleozoic that have a variety of curved dentition, but only the Helicoprion committed to the full spiral.

[Auspex]

The whole "single-row-of-teeth" thing is so bizarre! They're all symphesial...

[markm]

Jesse, thanks for the response! I would love to tag along on a helico expedition!

Auspex, I agree! And the function of all symphyseal whorls may have been "trapping mechanisms" for ingested prey? I can't think of a different function...

[markm]

I still can't believe that the television documentary folks haven't embraced this topic. Helico researchers like Jesse and his mentor should be well known and well sponsored...Ray Troll would be icing on their cake. What a missed opportunity!

[Jesse]

Thanks Mark!

It was disappointing but good at the same time. We were rushing to try and get everything in order for the show, now we have time to get it all buttoned up nice and tight, and that is what's important, the science. Plus I don't much care for being on camera, not my kinda thing, I much prefer to be in a lab measuring landmarks or prepping fossils.

That being said, the show will probably still happen Ray is seeking private funding currently and we have quite a bit on film already. I think the impact will be better after we publish and then we can keep all rights to the material!

[DeloiVarden]

Please let us know when you guys are ready to publish your work or when a show occurs, so we can all tune in!

[Jesse]

LOL, you can bet on it, you guys will probably be the 4th people to find out!

[jpc]

jesse... interesting discussion. Have you tried CT scanning these things? I think they are found in concretions in our area (did I learn that from you?), so that might make it tough, ... but who knows.

Edited April 28, 2012 by jpc

[micropterus101]

I think its possible a ball of teeth could be on its head heres a link to a ratfish which has a ball of teeth on its head. poor pic but shows it better then other pics i could find.

http://whyevolutionistrue.wordpress.com/2009/09/28/thats-not-ratfish-genitalia-thats-ratfish-genitalia/

[Jesse]

Have you tried CT scanning these things?

Yes, with stunning results! The concretions can be very difficult to scan, but like in the old star treks, we just give it more power, LOL.

Are you the same researcher that was supposed to go on a Helico field trip with us?

[Jesse]

I think its possible a ball of teeth could be on its head heres a link to a ratfish which has a ball of teeth on its head. poor pic but shows it better then other pics i could find.

http://whyevolutioni...fish-genitalia/

When Ray Troll was here earlier this year and we had all had a few beers, this very idea came up! It seems that these forehead appendages are used by the ratfish foe sexual display, and for lack of a softer term, for leverage during mating. Ray brought up that the tooth whorl of Helicoprion was used for the same purpose and may sit on his forehead.

It is a cool idea and would make for an interesting looking shark, as if it could get much stranger looking. As it turns out though the tooth whorl is positively a lower jaw structure. It has been found in connection with meckle's cartilage which is distinctive in appearance, and the aforementioned CT scans support the lower jaw evidence.

I have to say I am really enjoying hearing these different ideas, you guys have some great hypothesis and questions and it's nice to hear alternative ideas from time to time!!

[jpc]

Yes, with stunning results! The concretions can be very difficult to scan, but like in the old star treks, we just give it more power, LOL.

Are you the same researcher that was supposed to go on a Helico field trip with us?

No, that's not me, but if there's an opening, I would be thrilled to be involved. As if I don't have enough thngs to do this summer.

[Jesse]

I try and get to the mines at least 3-4 times per year, and will probably start going next month. When I get things set up and rolling this year I'll shoot you a pm and we can try and arrange it. There is A LOT of material to look through so the more trained eyes the better!

This invitation is good for any other members that are in the area and interested in looking for sharks!

[Bill]

Thanks Jesse, I understand that much better now, with the cartilage diagram.

I think its possible a ball of teeth could be on its head

Ha! That was my next question/suggestion.

I was thinking evolutionary cephalic spine experiment, gone wrong.

I believe shark teeth are modified scales, which migrated to the jaws. (I read something like that, anyway). So, as with other cephalic spines, it could have been head mounted.

Jesse' reply has answered that though.

Edited April 28, 2012 by Bill

[Auspex]

...It seems that these forehead appendages are used by the ratfish for sexual display, and for lack of a softer term, for leverage during mating. Ray brought up that the tooth whorl of Helicoprion was used for the same purpose and may sit on his forehead...

Pretty unlikely, but it would explain why they went extinct!

[xonenine]

fascinating thread Jesse,

all the most interesting looking PDFs are restricted access for myself, do you have any other recommended links for reading more?

thanks, Carmine

Edited April 28, 2012 by xonenine

[Jesse]

Shoot me a pm with the PDF you are looking for, chances are that I have a copy of it, I'm up to 60 PDFs for Helico.

[RickNC]

I always figured the whorl laid flat on the bottom of the lower jaw. The roof of the mouth could pin prey against the whorl and maybe a side to side motion of the lower jaw could grind the prey against the tooth whorl. I haven't really read much on these animals so maybe it has been found the whorl doesn't lay flat. The theory like the picture in the first post just doesn't look possible.

[Jesse]

Someone recently emailed us a picture they had made of Helico, and it's mouth was set up just like you are describing. It is a novel idea and as far as I know completely unique as no one has published any photos like this.

Back in 1966 a Danish researcher published a paper on Helicoprion from the phosphoria formation here in Idaho and he was the first to definitively say it was in fact upright in the lower jaw. He described a specimen that has a large amount of upper and lower jaw material preserved with the whorl, which supports the upright orientation. But even with this specimen the upright model still has problems. The whorl occupies a large amount of the mouth leaving little room for prey to be swallowed.

I'll agree it really doesn't make much sense, I still have trouble understanding how this shark could effectively feed.

[jpc]

Thanks,

I try and get to the mines at least 3-4 times per year, and will probably start going next month. When I get things set up and rolling this year I'll shoot you a pm and we can try and arrange it. There is A LOT of material to look through so the more trained eyes the better!

This invitation is good for any other members that are in the area and interested in looking for sharks!

Thanks, Jesse. PM me when you look like you might be oging, and I'll check my shcedule, which is already pretty full for the summer, but I do have a trip to Yellowstone planned for sometime in July. If the timing is right I could tack a quarry trip onto that since I'll be in the neighborhood.

[Coco]

Very interesting subject. I have difficulty in understanding that is "whorl". Should you to put a drawing or a photo to permit me to understand please ? (Tte translator doesn't help me on this word !)... Thanks.

Coco