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Jesse

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If we found any helicoprion material what is the pollicy on keeping it?

Your first action should be to go and buy a lottery ticket, it will definitely be your lucky day. After that I think it depends on the state, and the property where its found.

"They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things."

-- Terry Pratchett

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I have wondered if Helicoprion was sort of the sperm whale of its time. The modern sperm whale (as an adult) has teeth only in its lower jaw and it pins its prey against its upper jaw before swallowing it. The upper jaw of Helicoprion may have had a deeply recessed groove to accommodate the "buzzsaw" so it wouldn't puncture itself every time it closed its mouth. Since it lived before there were large marine reptiles or mammals, the teeth would not have struck sturdy bones. It could have eaten large bony fish and other sharks without the teeth suffering from wear especially it was swallowing them whole. It might have liked large jellyfish as sea turtles do today.

What other sharks or other organisms are found in the same formations?

Are large unshelled cephalopods known from the Paleozoic? I think the oldest known octopus is from the Cretaceous or perhaps the Late Jurassic but it had ancestors too and its ancestors had relatives. Maybe Helicoprion simply decapitated large nautiloids and ammonoids without risking damage to its teeth by biting the shell or maybe it shook out what it could from the shell.

Is it possible that each individual had a right and left whorl? That would make it a larger animal.

I used to wonder if it was a spiral of teeth at all because it was so weird, but after seeing Edestus teeth and its sort of half-whorl, I was able to see it like that.

Looking forward to the article,

Jess

We know for sure that the teeth are being added on the "back end" of the whorl, the newest tooth is also the largest tooth. The baby teeth are retained in the inner volutions of the spiral, continually pushed in towards the center as new teeth are added. The process by which sharks grow their teeth prevents them from starting small and continuously growing larger. So from that we can infer that they produce a new tooth at the back end of the jaw and that tooth progresses forward will eventually become enveloped under the "gums" and stored within the spiral. All the tooth share a common root and they all receive nutrients for the entire life of the shark, so technically it can be thought of as a single tooth with multiple crenulations.

I agree with you that it most likely ate almost exclusively soft bodied prey. I have examined almost 100 of these fossils and seen pictures of another 50 or so and have not yet seen any broken or worn teeth, not even a scratch. When you look at the environment it was roaming there were plenty of soft bodied meals such as nautiloids, ammonoids, small fish, holocephalans, and possibly euryptyrids.

I'm not so sure this shark was a reef hunter though, the formations they are found in are typically associated with mid-deep ocean deposits. We know that there needs to be fairly deep, low oxygen areas to facilitate the large deposits of phosphates we find them in. That is not to say that they didn't just die there and lived in another area...I also agree that Helicoprion most likely had a narrow head and a slim body shape.

I know I have been teasing you great members here for a while with the promise of real answers and I must apologize for that! However, we are making the final push this month to get our research finished and published, hopefully submitting 3 of the 4 publications by the end of the month! I can confidently say that almost all of the questions surrounding this enigmatic shark? have been answered, and I am dying to share all that I know with you guys! So please stand by, I promise it will be worth the wait!!

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  • 1 month later...

I am sorry guys, I was away for a while :blush:

The good news is that our first publication has made it through review and revision and has been accepted and will be out very soon!!!

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I have been fascinated by this shark since I saw a pic of it when I was about 7. Not fascinated enough to delve into it to the level you have Jesse. LOL But I am certai glad you and the others have. I can't wait to read your papers.

So let me ask this. You say the teeth grow backwards of what logic dictates, and twirl on into the jaw. So teeth are never shed and simply stay with the shark. What would be the advantage of this? I certainly can't think of a good reason for an animal of any sort to retain old teeth that are constantly replaced. Especially considering that the teeth not being used are now a biological burden as the animal now has to provide blood and nutrients to retain a uselss structure. A single tooth with multiple crenulations seems to be exactly what it is, but again, it seems to be a waste of energy and space.

Which leads to, if there are examples of single teeth, I would presume they occur simply due to damage to the whorl breaking it off. How many single tooth examples are there?

The entire whorl is a single tooth, all of the crowns share the same root. So far helicoprion is the only shark found that grows it's dentition like this, edestus is similar but they shed their older teeth. It is a very inefficient adaptation especially given that all crowns still have active nutrient vessles. The only reason that we can come up with for them retaining the whole spiral is 1) each successive volution supports the growing one, and 2) they just simply had no mechanism to shed them, that came a bit later.

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If we found any helicoprion material what is the pollicy on keeping it?

That depends on who arranges the visit and what the condition of the specimen is. The problem now is that the guy that was letting us visit the mine, wasn't authorized to do so. We have to go through official channels now, and that usually means that it is a museum sponsored trip which means that they would be the legal owners. Also if it is a private trip any fair-exceptional finds would be retained by the museum.

Trips can be made, there are just a few extra hoops to jump through. 4 were found there last summer...that we were told about.

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I have wondered if Helicoprion was sort of the sperm whale of its time. The modern sperm whale (as an adult) has teeth only in its lower jaw and it pins its prey against its upper jaw before swallowing it. The upper jaw of Helicoprion may have had a deeply recessed groove to accommodate the "buzzsaw" so it wouldn't puncture itself every time it closed its mouth. Since it lived before there were large marine reptiles or mammals, the teeth would not have struck sturdy bones. It could have eaten large bony fish and other sharks without the teeth suffering from wear especially it was swallowing them whole. It might have liked large jellyfish as sea turtles do today. This hypothesis has been published before, Lebedev 2007, pm me your email and I will send you a PDF copy.

What other sharks or other organisms are found in the same formations? There are some very large nautiloids, I put a picture of one on here a couple of years back, smallish (average 2 feet) fish, small nautiloids of a different species, conodonts, some very large heavily armored fish, holocephelans, and assorted brachs and snails. There were plenty of prey items around that were soft enough to not damage the teeth, and there most certainly were octopii and their like around as well that just didn't preserve.

Are large unshelled cephalopods known from the Paleozoic? I think the oldest known octopus is from the Cretaceous or perhaps the Late Jurassic but it had ancestors too and its ancestors had relatives. Maybe Helicoprion simply decapitated large nautiloids and ammonoids without risking damage to its teeth by biting the shell or maybe it shook out what it could from the shell. You are inside my head on this one!

Is it possible that each individual had a right and left whorl? That would make it a larger animal. This is not possible, the publication just published is a detailed analysis of CT scans that revealed upper and lower jaws.

I used to wonder if it was a spiral of teeth at all because it was so weird, but after seeing Edestus teeth and its sort of half-whorl, I was able to see it like that.

Looking forward to the article, Thank you, coming soon!

Jess

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Did this shark spontaneously develop this weird jaw/tooth structure or is there intermediate evidence that it developed slowly from some other line of sharks?

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It is kind of unclear where Helicoprion came from. They are the only chondrichthyans known that grow dentition in a complete spiral, but they have some closely related cousins. They are almost certainly related to Edestus, which predates the earliest helicos by about 20 million years. There is also some speculation that Helicoprion is closely related to both Sarcoprion and Ornithoprion, who both have a have volution whorl of teeth. A couple of other likely ancestors are Huanohelicoprion and Sinohelicoprion, these also predate saw jaw by around 20 million years. Finally, the closest likely relative is a very little know shark named Shaktauites, of which only 1 partial fossil has been found. This shark has an almost complete very open single whorl, was found in the same quarry as H. bessinowi, and is roughly 6-10 million years older.

All that said, yes there is circumstantial and as of yet unsubstantiated evidence that they followed a long line of evolution that dead ended with them!

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I would love to see pics of any edestus or helicoprion related fossils. I want to see pics that suggest how the jaws were arranged in the head. I know there are some specimens out there. It is just very hard to find pictures of them. I was given a photo copy of an x-ray of an edestus hienrichi skull. Very cool. If there is anything else like that I would do anything to see it.

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I just got the galleys for our publication this morning, it will be in print in about 2 weeks. This publication has what you are looking for with helicoprion.

I have a few old publications that have some of helico's cousins that I can share.

This little guy is Ornithoprion.

post-5052-0-04236000-1360808121_thumb.jpg

post-5052-0-67373300-1360808145_thumb.jpg

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And Sarcoprion, sadly this specimen was serial sectioned so there are no real photographs of it :(

Thanks, that is very interesting. Did ornithoprion have any teeth?

Lately I have been thinking of the edestus jaw as being more of a beak than a jaw. The only thing in nature I can compare it to is the specialized beak of the crossbill bird. I wonder if it was a specialist for reaching into caverns to retrieve prey. Or possibly cutting off the heads of ammonites. Ammonites would not have been fast moovers, and therefore easy to possition for decapitation. The edestus beak and helicoprion whorl don't seem like they would be at all well adapted for catching quick or nimble prey.

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Today I came up with a new idea about helicoprion. What if the tooth whorl section had adapted with false coloration. The whorl having a lighter coloration and the rest of the shark having a dark coloration. The whorl would have resembled an ammonite swimming all by itself, making it even easier to fool cephalopods. Just a thought.

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To paraphrase the X-Files: The Tooth is out there! :D

I can't wait to read more, Jesse. Way cool.

Pete "NetDoc" Murray

Scuba Instructor/Trainer/Evaluator

NetDoc@ScubaBoard.com

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Thanks, that is very interesting. Did ornithoprion have any teeth?

Lately I have been thinking of the edestus jaw as being more of a beak than a jaw. The only thing in nature I can compare it to is the specialized beak of the crossbill bird. I wonder if it was a specialist for reaching into caverns to retrieve prey. Or possibly cutting off the heads of ammonites. Ammonites would not have been fast moovers, and therefore easy to possition for decapitation. The edestus beak and helicoprion whorl don't seem like they would be at all well adapted for catching quick or nimble prey.

It had teeth similar to rays, flat plate like teeth. It is put into the same category with helico because it is old and odd and has a partially curved symphyseal dentition block, I personally don't think it belongs in the same clade.

Technically the fossils found of edestus aren't jaws, they are tooth batteries. I have yet to find any published fossils that contain jaw material, the few pictures I have seen are most likely Caseodeus instead. The way the fossils are curved I would thing using them to pluck food up would be difficult, I imagine them as a big set of shears. But who knows, they make even less sense than helico does to me but I am hoping to get the opportunity to work on them in depth in the future!

I disagree about the speed of ammonoids and nautiloids of the time though, they would be very fast in retreat mode very similar to modern nautilus'. At least in the case of helico, with the global distribution of fossils in mind, I believe it was a fast moving open ocean predator.

Today I came up with a new idea about helicoprion. What if the tooth whorl section had adapted with false coloration. The whorl having a lighter coloration and the rest of the shark having a dark coloration. The whorl would have resembled an ammonite swimming all by itself, making it even easier to fool cephalopods. Just a thought.

This was the idea early on, back in the first couple of publications, that is why the early reconstructions have the whorl curled outside the head like a party favor. In 1966 Bendix Almgreen published on a fossil that he identified as having lower jaw and neurocranium preserved with the whorl. After that publication you start seeing the whorl reconstructed inside the lower jaw, except for the pub by John Long.

We do know that the fossils have a layer of tessarae cartilage encasing the inner volutions of the spiral that supports the idea that it was encased inside the lower jaw.

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To paraphrase the X-Files: The Tooth is out there! :D

I can't wait to read more, Jesse. Way cool.

Got an email today, we will be published on February 27th and this pub will answer many questions!

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Hi,

:goodjob::popcorn:

Coco

----------------------
OUTIL POUR MESURER VOS FOSSILES : ici

Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici
Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici
Mâchoires sélaciennes récentes : ici
Hétérodontiques et sélaciens : ici
Oeufs sélaciens récents : ici
Otolithes de poissons récents ! ici

Un Greg...

Badges-IPFOTH.jpg.f4a8635cda47a3cc506743a8aabce700.jpg Badges-MOTM.jpg.461001e1a9db5dc29ca1c07a041a1a86.jpg

 

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It had teeth similar to rays, flat plate like teeth. It is put into the same category with helico because it is old and odd and has a partially curved symphyseal dentition block, I personally don't think it belongs in the same clade.

Technically the fossils found of edestus aren't jaws, they are tooth batteries. I have yet to find any published fossils that contain jaw material, the few pictures I have seen are most likely Caseodeus instead. The way the fossils are curved I would thing using them to pluck food up would be difficult, I imagine them as a big set of shears. But who knows, they make even less sense than helico does to me but I am hoping to get the opportunity to work on them in depth in the future!

I disagree about the speed of ammonoids and nautiloids of the time though, they would be very fast in retreat mode very similar to modern nautilus'. At least in the case of helico, with the global distribution of fossils in mind, I believe it was a fast moving open ocean predator.

This was the idea early on, back in the first couple of publications, that is why the early reconstructions have the whorl curled outside the head like a party favor. In 1966 Bendix Almgreen published on a fossil that he identified as having lower jaw and neurocranium preserved with the whorl. After that publication you start seeing the whorl reconstructed inside the lower jaw, except for the pub by John Long.

We do know that the fossils have a layer of tessarae cartilage encasing the inner volutions of the spiral that supports the idea that it was encased inside the lower jaw.

I know that the whorl was encased. Even though it was encased it would still have roughly a rounded shape. False coloration is very common in nature. There are even some shark species that employ false eyes ecs. It would be impossible to prove, but I would still like to see an artist rendition of Helico with a fake ammonite on it's lower jaw.

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This is an image taken from a German publication from 1910, it was this paper that put out the ammonoid decoy hypothesis. I think this was the only published piece that reconstructed the shark with the idea of a decoy in mind.

post-5052-0-03369600-1361036297_thumb.jpg

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From the edestus skull X-rays I have seen, the " tooth battaries" are spaced far enough apart above, and below each other that they intersect near the very distal portion, creating somethig resembaling an elongated beak. It's not quite like what we are used to seeing in artist renditions where when the mouth is closed the " tooth battaries" cross way past eachother. When I saw the X-rays is when I came up with the crevasse cephalopod plucker hypothesis (As half baked as it might be ). Because edestus is possibly a more basal shark in the same family as helicoprion, and perhaps occupys a similar niche understanding it might help us to better understand helicoprion.

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