C. Auriculatus Query

[Daryl McEwen]

An experienced collector I met in NC recently told me that C. Auriculatus kept their adult teeth all their lives without the conveyor ability shared by modern and past sharks. He said this is why a lot of big rics are found with rounded tips and they relied on their side cusps heavily when the tips were worn or broken. Is this true?

[Gizmo]

I strongly doubt your friends assertion . I've found a bunch of Rics over the years and most have nice sharp tips!

[tracer]

:startle:

that's not it at all. the issue is that rics were extremely fond of eating hard candies, particularly jawbreakers.

[Auspex]

For that adaptation to have arisen in just one species (from a loooong lineage successfully doing elsewise) is unlikely in the extreme.

[Paleoc]

An experienced collector I met in NC recently told me that C. Auriculatus kept their adult teeth all their lives without the conveyor ability shared by modern and past sharks. He said this is why a lot of big rics are found with rounded tips and they relied on their side cusps heavily when the tips were worn or broken. Is this true?

NO

If they retained their teeth, the only teeth found would be from full grown sharks and after they died which would make them all large and very rare and usually associated. In addition, the teeth wouldn't grow (have your teeth got larger?) and they would all be from one size group. Teeth with thick roots are shed less often (you physically can't fit as many in a file and they are anchored more firmly) and they were feeding on whales which were thinner with less blubber than modern whales and thus bonier. Other sharks with thick roots (Parotodus for example) are also usually found with worn tips for the same reason (longer retention in the jaw).

Cusplets were a holdover from earlier ancestors (Otodus) and were probably of little use to the shark once it reached adulthood. They may have been some use to juveniles feeding on fish.

Edited November 6, 2010 by Paleoc

[tracer]

reasons for tooth tip wear and/or breakage are not mutually exclusive. there is no reason that there could only be one reason. and many who would elevate the value of teeth by attributing all tip wear and/or breakage to "feeding damage" are being disingenuous, unless they have some magical chain-of-events crystal ball with which they can unerringly determine whether every instance of tooth damage is pre- or post-mortem, and can also articulate how they know what caused the damage. some damaged tooth tips are caused by bulldozers...

[Daryl McEwen]

Hey guys, thanks for all the replies! I thought this guys was going out on a pretty long limb making this assumption based on one species vs. a specific trait shared by pretty much all other sharks, but he seemed like a fellow who was fairly well versed in fossil knowledge. This is why I presented the question to you. I've learned some new things here.

So the thicker the root on a shark tooth (like P. Benedeni, C. Auriculatus, C. Megalodon), the longer the tooth was retained in the jaw?

[non-remanié]

if were looking at a heavily rounded reworked numerous times tooth, sure i agree with what you are saying, but i would say this and any similar occurrences are almost certainly feeding damage since the tooth is otherwise in decent condition. yes i could think up some odd or complicated taphonomic scenarios that produce the same tooth, but they seem less likely than the obvious. also, if this "type" of tooth was more or even fairly commonly created through other processes than feeding damage we would see teeth that have missing roots very similar to the rounded blade of this specimen and we just dont see those teeth with perfect tip and one perfect rootlobe, but the other root is broken off and quite rounded in a similar fashion to the tip in this specimen. sure we see teeth with broken roots, but its clear what happened in those instances. it broke off...sometime. if the break is rounded, then the entire tooth is similarly rounded, not just the one rootlobe. i would argue that the tip rounding is much more prominent on this specimen and therefore can be fairly confidently referred to as feeding damage. is that convoluted enough for you tracer?

reasons for tooth tip wear and/or breakage are not mutually exclusive. there is no reason that there could only be one reason. and many who would elevate the value of teeth by attributing all tip wear and/or breakage to "feeding damage" are being disingenuous, unless they have some magical chain-of-events crystal ball with which they can unerringly determine whether every instance of tooth damage is pre- or post-mortem, and can also articulate how they know what caused the damage. some damaged tooth tips are caused by bulldozers...

Edited November 6, 2010 by toothpuller

[tracer]

please bear in mind that i don't deal in probabilities when labeling stuff. either i know what caused something, or i don't. a huge percentage of fossils found have breaks on them. either there's evidence of what caused the breaks, or there isn't. i'm not in the least saying that there are not a bunch of shark teeth out there with damage which occurred when the living shark bit something. what i'm saying is that most of the time there isn't any way to know that for sure.

in the current case, the tooth appears rounded, thinned, and worn on the tip. even if it was previously broken, it now appears to be anything but a straight break. why?

[non-remanié]

i do think we sort of agree tracer. but i take my previous comments back. a little. looking *closer* at the picture it does appear *fairly* reworked/transported from the rounded/lack of serrations near the rounded tip. probably it is best in this case not to jump to feeding damage just quite as quickly. *i* sure wouldnt put it in my book as the prime example of feeding damage, but many would not hesitate at all to do just that. but i still think its fair game to call most tip damage to megs feeding damage unless reworking is quite substantial. when you collect megs/rics/etc in various states of preservation and recent water wear and you get to see what is often wrong with the teeth its easy to come to the conclusion that at least a good portion of what you see has to be related to feeding damage. any specific case you might be able to argue, but seeing the same exact type of tip damage over and over again really makes it hard to deny as a very common phenomena. what you are saying is that basically we should never label anything as feeding damage because we dont know it to be 100%? i think that is a little bit obscene. it seems to me that just about every aspect of paleontology is pretty much ALL about probabilities...

please bear in mind that i don't deal in probabilities when labeling stuff. either i know what caused something, or i don't. a huge percentage of fossils found have breaks on them. either there's evidence of what caused the breaks, or there isn't. i'm not in the least saying that there are not a bunch of shark teeth out there with damage which occurred when the living shark bit something. what i'm saying is that most of the time there isn't any way to know that for sure.

in the current case, the tooth appears rounded, thinned, and worn on the tip. even if it was previously broken, it now appears to be anything but a straight break. why?

Edited November 7, 2010 by toothpuller

[tracer]

i do think we sort of agree tracer. but i take my previous comments back. a little. looking *closer* at the picture it does appear *fairly* reworked/transported from the rounded/lack of serrations near the rounded tip. probably it is best in this case not to jump to feeding damage just quite as quickly. *i* sure wouldnt put it in my book as the prime example of feeding damage, but many would not hesitate at all to do just that. but i still think its fair game to call most tip damage to megs feeding damage unless reworking is quite substantial. when you collect megs/rics/etc in various states of preservation and recent water wear and you get to see what is often wrong with the teeth its easy to come to the conclusion that at least a good portion of what you see has to be related to feeding damage. any specific case you might be able to argue, but seeing the same exact type of tip damage over and over again really makes it hard to deny as a very common phenomena. what you are saying is that basically we should never label anything as feeding damage because we dont know it to be 100%? i think that is a little bit obscene. it seems to me that just about every aspect of paleontology is pretty much ALL about probabilities...

when i see "broken" tips of fossil shark teeth rounded off and polished, i just never figure it happened in the shark's mouth. if you want to deal with probabilities, then be sure to consider the length of time the tooth was in a shark's mouth, compared to the length of time between the time it was lost, and the time you found it.

i do not know if testing of relative hardness of different areas of fossil shark teeth has been done. inasmuch as the root is more permeable/porous and thicker than the tip, i'm not sure which "fossilizes" sooner/harder and how much of a difference there is in susceptability to breakage. i also don't know which part, if any, of fossil teeth tends to get exposed soonest from the matrix, if there is any tendency for that to happen due to the shape of the things. but to me, i can't "lump" breakage into a same or similar category just due to the location of a break. if you yank teeth from a freshly-caught shark, and put them in a vise and break the tips, how do they break? is there any splintering effect on the end? to me, looking at a bunch of "feeding damage" on the still-in-place teeth of modern sharks would give me a point of reference for comparison to damage found on fossils. breaks on fresh teeth, in my mind, should be different in appearance from breaks on old fossil teeth.

i'm not telling anybody how to label their stuff. i've just got hundreds of fossils with breaks that i give no attribution to since there's no indication on the fossil regarding what caused the break.

[Paleoc]

I think we are looking at an easy experiment here. One I may conduct in the near future. Take a couple (or more) of expendable fossil teeth and put them in a rock tumbler with some sand. Have one tooth with a broken tip. I predict the root being the softest will wear the worst but it will be an interesting outcome either way. Take some before and after images.

[Auspex]

A tooth stuck in a river bed/bank with the root buried/protected somehow would explain some of the smooth round tips on nice roots.

[non-remanié]

logically, i agree with all of what you have said and your proposed tests would be quite interesting! although, just the fact that you mention needing a vise to preferentially break the tips of shark teeth without damaging anything else is likely a hint in itself i believe... i would love to better understand the entire fossilization process and have detailed studies directed related to fossil tooth/bone. it just seems like theres not much research material available on this topic. but people have definitely observed feeding damage in modern sharks jaws. i dont think someone just invented this widespread concept of "feeding damage" without any modern shark correlation. it exists, is common, and completely logical. i think if you collected sharks teeth more often and colelcted from different layers with different modes of preservation ranging from as close to in situ as possible to somewhat transported to heavily reworked to any combination of those on top of recent water exposure wear, you would come to the same conclusion; that it is highly probable these are examples of feeding damage the vast majority of the time (given the probability slightly decreases with the amount of reworking/transport observed in any given specimen). when you see pristine (completely unreworked or transported) extremely fragile sharks teeth with perfectly preserved rootlobes and cusplets only millimeters thick and yet the seemingly much more solid and thicker crown suffers from extreme, seemingly violent damage, or, for instance, serrations being "sheared" off, then you too would most likely come to the logical conclusion as to what caused most of this type of damage. also you would see that many teeth from heavily reworked horizons just dont magically seem to have the tips of crowns broken off while the rest of the tooth remains in very good condition. (of course i admit we can easily dream up scenarios that can account for such things such as Auspex so succinctly did) no i dont have data, but if you collected in those layers yourself i think you would see the same patterns. personally, i dont have any labels that even mention feeding damage, and i dont really care one way or another. i want to find perfect teeth and if its got a broken tip its a disappointment whether i think of it as feeding damage or anything else. theres always a shadow of doubt, but it seems like you were almost offended that someone came to the same conclusion many shark tooth collectors would reach if they were forced to consider the issue. of course logical doesn't guarantee mathematical certainty, but paleontologists of any ilk rarely get to deal with absolutes.

when i see "broken" tips of fossil shark teeth rounded off and polished, i just never figure it happened in the shark's mouth. if you want to deal with probabilities, then be sure to consider the length of time the tooth was in a shark's mouth, compared to the length of time between the time it was lost, and the time you found it.

i do not know if testing of relative hardness of different areas of fossil shark teeth has been done. inasmuch as the root is more permeable/porous and thicker than the tip, i'm not sure which "fossilizes" sooner/harder and how much of a difference there is in susceptability to breakage. i also don't know which part, if any, of fossil teeth tends to get exposed soonest from the matrix, if there is any tendency for that to happen due to the shape of the things. but to me, i can't "lump" breakage into a same or similar category just due to the location of a break. if you yank teeth from a freshly-caught shark, and put them in a vise and break the tips, how do they break? is there any splintering effect on the end? to me, looking at a bunch of "feeding damage" on the still-in-place teeth of modern sharks would give me a point of reference for comparison to damage found on fossils. breaks on fresh teeth, in my mind, should be different in appearance from breaks on old fossil teeth.

i'm not telling anybody how to label their stuff. i've just got hundreds of fossils with breaks that i give no attribution to since there's no indication on the fossil regarding what caused the break.

[tracer]

again, what i think i was saying was that i've noted that leaps in logic frequently seem to favor the sexiness or value of the fossils in some way, and it isn't just with shark teeth. i have never once stated that i don't think feeding damage accounts for the damage on a number of shark teeth. but that belief alone cannot logically be extended to assuming that it is the case with any particular tooth. any argument ad hominem regarding my level of collecting experience aside, i continue to recognize another logical fallacy (a broken syllogism ) in concluding that (1) many shark teeth tips were damaged in feeding... (2) the specimen in question is a shark tooth and has tip damage, therefore (3) the damage was due to feeding.

picture yourself dumping out three bucketsful of broken meg teeth on the floor. oops, dang, a tooth tip broke off one when it hit the floor! ignore that! it doesn't count! ok, now, sort all the teeth into piles based on how they're broken. some are split down the middle, some are split off center, some have broken root lobes, and some are even just broken middle fragments, almost unrecognizable. and then there are the ones with broken tips. so then you take alllllllll the other pieces, and put them back in the buckets. you take the teeth with tip damage and discount them a bit and write the description "would have been a 5.99 incher if it wasn't for the feeding damage, but a beast like this had to eat!!!!!"

i'm just sayin'...but i've beaten this dead horse to the extent that if i don't stop somebody's gonna be claiming he was predated upon by chupacabras, so i give up, you win!

[Foshunter]

Looks like this mystery has been solved but would like to add my two cents. The gentleman that told you they kept their teeth all their life forgot one detail, that the family tree came from Otodus that shed teeth to Auriculatus that he claimed that didn't to Angustidens that did and the tree remained the same through Meg. So plain and simple, "That dog don't hunt".--Tom

[bear-dog]

:phew: I'm getting brain cramps trying to soak this all in. :lol:

[Coco]

All the sharks, all the skates and all the chimaera are cartilaginous fishes (selachians).

Contrary to mammals, their teeth are not prisoners of their jaw. They form in a gingival, very soft tissue. It is the reason for which we find almost never teeth fossilized with a piece of jaw, because would be needed conditions of very very special fossilizations to have kept them so.

If teeth are not set in a jaw, they cannot stay in the mouth of the shark all its life.

Coco

[non-remanié]

agreed, beaten to a pulp, and i already backed off on my personal opinion on the specific tooth in question. at the very least there is way too much grey area to bother arguing about that specific tooth, even though experience tells me that its still more likely that the tooth did suffer feeding damage before abrasion/rounding. but i really dont think that feeding damage on a shark tooth in any way can add value it. and in your bucketful of diver megs, for example, its pretty easy to spot fresh breaks on sharks teeth. i'd say that the market only cares how shiny, perfect, large or colorful a tooth is. any feeding damage or other breakage is only an imperfection, so i dont see any added sexiness or value. theres just way too many shark teeth out there... but i completely understand your point considering other fossils and dealer hype trying to make the flaws desirable. there is too much of that.

again, what i think i was saying was that i've noted that leaps in logic frequently seem to favor the sexiness or value of the fossils in some way, and it isn't just with shark teeth. i have never once stated that i don't think feeding damage accounts for the damage on a number of shark teeth. but that belief alone cannot logically be extended to assuming that it is the case with any particular tooth. any argument ad hominem regarding my level of collecting experience aside, i continue to recognize another logical fallacy (a broken syllogism ) in concluding that (1) many shark teeth tips were damaged in feeding... (2) the specimen in question is a shark tooth and has tip damage, therefore (3) the damage was due to feeding.

picture yourself dumping out three bucketsful of broken meg teeth on the floor. oops, dang, a tooth tip broke off one when it hit the floor! ignore that! it doesn't count! ok, now, sort all the teeth into piles based on how they're broken. some are split down the middle, some are split off center, some have broken root lobes, and some are even just broken middle fragments, almost unrecognizable. and then there are the ones with broken tips. so then you take alllllllll the other pieces, and put them back in the buckets. you take the teeth with tip damage and discount them a bit and write the description "would have been a 5.99 incher if it wasn't for the feeding damage, but a beast like this had to eat!!!!!"

i'm just sayin'...but i've beaten this dead horse to the extent that if i don't stop somebody's gonna be claiming he was predated upon by chupacabras, so i give up, you win!