Shark Tooth Composition & "digested" Teeth

[cowsharks]

Occasionally I find a shark tooth that is so nasty looking that rather than leaving it lying on the beach, I pick it up and take it home for further inspection. Usually the "nasty" looking tooth is a tiger shark, hemi, mako, or maybe even a small Meg. Years ago I heard someone refer to a tooth at one of our club meetings as a "digested" tooth, one that had been swallowed by the shark, "nastified" by its stomach acids, and exited later on perhaps not looking as nice as when it was swallowed. I took this explaining with somewhat of a grain of salt so to speak because I thought how can you really tell the difference between a digested tooth and one that is just plain old worn either by being re-worked or tossed about the rocks and sandy gravels on a beach. So with that I did a little searching to find out what the composition of a shark's tooth is made up of.

One website (http://stoneplus.cst.cmich.edu/zoogems/teeth--.html) describes it as follows:

"DESCRIPTION: Teeth include at least three different kinds of tissues: Enamel, dentin(e) and cementum. The chief inorganic constituent is apatite [Ca₅(PO₄)₃(OH) -- see, however, bioapatite description in BONE entry], which occurs as flattened needle-like crystallites and is described as probably containing “the phases OHA [Ca₁₀(PO₄)₆(OH)₂], DOHA [Ca₉(HPO₄)(PO₄)₅(OH)], NCCA [sodium and carbonate containing apatite], and dolomite [CaMg(CO₃)₂ ]” with a “heterogeneity in enamel composition from one tooth to another and within one tooth due to variations in the composition of the mineral” (Driessens & Verbeeck, 1990, p.142 & 109, respectively). The apatite of sharks' teeth, however, is said to be fluorapatite -- Ca₅(PO₄)₃F (Vinogradov, 2001)."

This is a decent description, but there was no diagram to show me where the dentin(e) and cementum portions of the tooth are. What material is the root portion of the tooth considered?

I'm not looking to do a ton of scientific research on the composition of the teeth, but what I'd like to be able to do perhaps is have a better understanding of how to differentiate between the typical worn tooth and one that might be digested. I would think that a digested tooth should be easier to recognize because the entire tooth would have taken a bath in the stomach acids of the shark, and therefore the whole tooth should be affected?

I thought someone had told me that the only part of a fossil shark tooth that is unchanged by fossilization is the enamel. However, I read the following excerpt from the site:

http://www.suite101.com/content/formation-and-uses-of-shark-tooth-fossils-a129065

"How Shark Teeth Become Fossils

This sediment covering prevents bacteria and oxygen from reaching and damaging the tooth. In a process called permineralization, the tooth absorbs minerals in the sediment. The minerals replace the tooth enamel and dentine. Over thousands of years, it is this chemical exchange that preserves the tooth and creates what is known as a fossil."

So, if a shark swallowed a tooth, would the stomach acids have done more immediate damage to the softer root portion than compared to the rest of the tooth which was enamel?

Over this weekend I'll search through my collection to find some examples of these teeth I referred to earlier as "nastified". They might be examples of digested teeth, if so they are cooler to have than teeth that are just flat out worn and ugly because they spent too much time in the beach rocks and gravels before I found them.

Daryl.

[url=http://www.suite101.com/content/formation-and-uses-of-shark-tooth-fossils-a129065#ixzz1AvHLjXjm][/url]

[Boesse]

Well... the division into enamel, dentine, and cementum applies to mammals - I'm not sure how it applies to "reptiles", and it definitely doesn't apply to sharks. From what I remember, sharks have no equivalent of cementum - and their enamel and dentine equivalents are mineralogically different (in terms of structure and genesis), and referred to as enameloid and osteodentine.

Enameloid is nearly 97-98% pure calcium phosphate, and has much less in the way of organic (i.e. nonsoluble) components. The enameloid of a shark tooth is more soluble than the osteodentine, and the enameloid is more quickly digested/acid etched. Acid etching results in pitting of the tooth (or bone) surface.

Second - if the roots of teeth are more damaged than the crowns, than it isn't digestion at work.

Bobby

[Al Dente]

Daryl

Here are a couple of photos of teeth from Lee Creek. I believe the tooth on the left of each set is a partially digested example of a shark tooth.and the tooth on the right is a normal example. They have a certain luster that is difficult to photograph.

[patrick hendriks]

Shouldn't one ask first if a tooth can survive the acid in the stomage of a shark. On our Dutch forum we had a similar discussion for a few years. People also thought that they had some teeth wich had been swallowd by the shark, and that fossilized. But considering the fact that a shark swallows a lot of different material when he was eating his prey and nothing has ever been found of it. So you have to ask if the acid in the stomage is so strong that it alsmost desolves everything. Maybe a biology professor could be asked if he knows how stong the acid in a modern shark stomage is, and if it could be reproduced in a laboratorium. And than put a modern shark tooth in this solution to see what would happen. The second question would be how long it would take for a shark tooth to pass threw its degestion system, and would that time be short enough to survive.

Also i've found several teeth that looked as being bitten by the shark itself. These teeth all hace a clean smooth cut, but they all have the same enamel as other fossilized teeth. I've never seen "swallowed" teeth that have these same smooth cut on it, and also show details that they have been in contact with the acid in the stomage of a shark.

Best regards Patrick

[Paleoc]

But considering the fact that a shark swallows a lot of different material when he was eating his prey and nothing has ever been found of it.

Best regards Patrick

Actually regurgitated bone isn't uncommon as Sharks regurgitate indigestible items. I doubt that they would regurgitate teeth which are probably too small too worry about but they could come back up with a bone or something else.

http://www.oceansofkansas.com/bite.html

[Tony Eaton]

It seems like you have to find the tooth in situ with a good sample population to know for certain it wasn't altered after being deposited. Some ocean sediment can be exposed to highly acidic environment for a very long time when buried.

[non-remanié]

I consider these teeth disgested, whether it be by the shark itself, or perhaps a predator croc upon its carcass, I can't say. These teeth come out of a deposit that generally produce mostly pristine, not reworked, and not heavily permineralized teeth. Indeed, these teeth seem pretty fragile and I suspect that if they were exposed to any sort of extended transport process or reworking I don't believe they would remain in the fossil record. These "digested" teeth do not really come in degrees; in the deposit its either extreme like these ones or pristine. So my reasoning is that some biological process was clearly at work prior to fossilization.

Edited January 14, 2011 by toothpuller

[Sal]

I really can't say what a digested shark tooth looks like, let alone a fossilized one, but I do know what digested reptile teeth look like. They look very clean (once you get all the snarge off them) They are usually white (unless left in the feces for a while then they stain a bit) and still are sharp. This is a picture of a retrieved Komodo Dragon tooth. As you can see the serrations are still visible. I don't really think a tooth passing through a shark's gut will look any different than one that just fell out.

[Al Dente]

The reason I believe these teeth were digested is that the enamel is dissolved but the rest of the tooth is in fair condition. These teeth were found alongside hundreds of pristine teeth that have no evidence of their enamel being dissolved. There are a couple of published papers that discuss similar teeth. One is by Ken Shumada titled "Shark tooth bearing coprolite from the Carlile Shale (Upper Cretaceous), Ellis County, Kansas" Transactions of the Kansas Academy of Science 100(3-4), 1997. He describes a coprolite that contains a Ptychodus tooth. The tooth had its enameloid dissolved, presumably by the digestive acids of whatever ate it. Another paper is by Daniel Fisher titled "Crocodilian scatology, microvertebrate concentrations, and enamel-less teeth" Paleobiology vol. 7, no. 2 , 1981. Fisher fed various animal remains, including a shark tooth, to crocodilians. One of the results was dissolved tooth enamel. The reasons he gives for the dissolved enamel are the same that Bobby gives in the above post.

[cowsharks]

Guys, thanks so much for the info and posting your pics. All of the teeth you guys posted as "digested" look exactly like the ones I am referring to. What's funny is that I'm willing to hold on to these nasty looking teeth if I know they they got that way because they were possibly digested, but if it's just a plain ole' worn tooth, it goes in the shoebox with all the other broken and worn teeth.

In my search for other "digested" teeth I came across a raptor tooth on paleodirect that apparently was digested:

http://www.paleodirect.com/pgset2/dt6-133.htm

I thought it was interesting that they noted that it was digested and that only the serrations were missing. Otherwise, it doesn't look too bad compared to how the digested shark teeth look.

As I go through some of my Miocene collection this weekend sorting teeth from boxes and baggies to drawers and riker mounts, I'll be on the lookout for more of these digested teeth. I know I have at least one or two with zero enamel.

Patrick, I'm curious as well about the type of laboratory test you mentioned. It would be neat to try such an experiment on some modern shark teeth, if we could just figure out what kind of acid sharks have in their stomach.

Does anyone know if the enamel on a fossil shark tooth is the original enamel, or has it too been permineralized?

thanks,

Daryl.

[Boesse]

I thought I'd mention that a squamate like Varanus (komodo dragon) is not a very good comparison with a shark, as sharks have a much different mode of feeding and digestion.

It is apparent from forensics studies of human remains salvaged from shark guts that they can 'stow' carcass parts in parts of their stomach without digesting them, and saving the food for a later time - resulting in minimal digestion. Modern forensics cases also have documented acid etching on bones in shark stomachs. Basically - not ALL vertebrate skeletal elements which pass through a shark's GI tract will be acid etched (indeed, certain elements may be regurgitated earlier, for example).

Bobby

[PaleoDirect]

Guys, thanks so much for the info and posting your pics. All of the teeth you guys posted as "digested" look exactly like the ones I am referring to. What's funny is that I'm willing to hold on to these nasty looking teeth if I know they they got that way because they were possibly digested, but if it's just a plain ole' worn tooth, it goes in the shoebox with all the other broken and worn teeth.

In my search for other "digested" teeth I came across a raptor tooth on paleodirect that apparently was digested:

http://www.paleodirect.com/pgset2/dt6-133.htm

I thought it was interesting that they noted that it was digested and that only the serrations were missing. Otherwise, it doesn't look too bad compared to how the digested shark teeth look.

As I go through some of my Miocene collection this weekend sorting teeth from boxes and baggies to drawers and riker mounts, I'll be on the lookout for more of these digested teeth. I know I have at least one or two with zero enamel.

Patrick, I'm curious as well about the type of laboratory test you mentioned. It would be neat to try such an experiment on some modern shark teeth, if we could just figure out what kind of acid sharks have in their stomach.

Does anyone know if the enamel on a fossil shark tooth is the original enamel, or has it too been permineralized?

thanks,

Daryl.

Hi Daryl,

If you compare the one you cite with this one or others http://paleodirect.com/pgset2/dt6-119.htm, you will see the difference is more than simply serrations missing. There is a microscopic layer covering the entire tooth that is wrinkled and partially dissolved, not just missing serrations. The digested tooth was found in the exact same prehistoric swamp micro-site as these superb teeth like the one I cite, and on the same level or layer so, the tooth that we are calling digested is not from a former "high-energy" enviroment like a prehistoric river bed where the tooth could have been worn by external forces. If it was, then many of the teeth would share similar functions. I have not seen many teeth like this digested one. We have had a couple from Morocco with the same characteristics but it is not common.

I would think that a dinosaur tooth would be easier to pass through the entire digestive tract with less chance of getting stuck or causing internal organ damage than the extreme point and razor edges that shark teeth might pose in a shark. Still, you don't see many of these digested teeth of any type. Maybe some get fully digested or eaten by stomach acid to the point that fossilization is not good enough to preserve them in ancient deposits.

Edited January 15, 2011 by PaleoDirect.com

[Guest N.AL.hunter]

I just want to say that the Komodo Dragon tooth is really neat. First one I've seen. Too bad it isn't a fossil one.

[cowsharks]

Hi Daryl,

If you compare the one you cite with this one or others http://paleodirect.c...et2/dt6-119.htm, you will see the difference is more than simply serrations missing. There is a microscopic layer covering the entire tooth that is wrinkled and partially dissolved, not just missing serrations. The digested tooth was found in the exact same prehistoric swamp micro-site as these superb teeth like the one I cite, and on the same level or layer so, the tooth that we are calling digested is not from a former "high-energy" enviroment like a prehistoric river bed where the tooth could have been worn by external forces. If it was, then many of the teeth would share similar functions. I have not seen many teeth like this digested one. We have had a couple from Morocco with the same characteristics but it is not common.

I would think that a dinosaur tooth would be easier to pass through the entire digestive tract with less chance of getting stuck or causing internal organ damage than the extreme point and razor edges that shark teeth might pose in a shark. Still, you don't see many of these digested teeth of any type. Maybe some get fully digested or eaten by stomach acid to the point that fossilization is not good enough to preserve them in ancient deposits.

Hi PaleoD, thanks for the additional references on your dino teeth. Even though the digested raptor tooth is missing serrations, I think it makes it a lot more interesting than just a similar tooth that has it's serrations worn off. Like the digested shark teeth I have found, knowing that they look the way they do makes them more collectable, otherwise I would toss them into the large shoebox with the other broken and worn shark teeth.

BTW, you have a great site with lots of examples of things I haven't been able to find anywhere else.

Daryl.

[PaleoDirect]

Hi PaleoD, thanks for the additional references on your dino teeth. Even though the digested raptor tooth is missing serrations, I think it makes it a lot more interesting than just a similar tooth that has it's serrations worn off. Like the digested shark teeth I have found, knowing that they look the way they do makes them more collectable, otherwise I would toss them into the large shoebox with the other broken and worn shark teeth.

BTW, you have a great site with lots of examples of things I haven't been able to find anywhere else.

Daryl.

Thank you!

[Hunter0811]

I think this is a digested shark tooth, you can really see the whole tooth is affected by some sort of acid, but what i'd like to know. Are these teeth rare because i can't find much information about them on internet. Also the tooth is 3,1cm long and the species is Isurus/Carcharodon Hastalis.

[fossilnut]

Daryl I came across this post of yours while trying to get information on the chemical composition of shark teeth roots. You asked that question but got no response that I can see. Have you learned anything further about root composition? Also whether the enamel is the original or has it been permineralized?  Appreciate any info or references you may have. Thanks Tom

[Rayminazzi]

Whether this is relevant or not I thought here would be a good place to get opinions and add something to the conversation, these teeth come from the contact area of the pecan gap chalk and the Austin chalk in South Texas near San Antonio, I can't say about other areas of this contact but here all of the shark teeth are rootless, acidic environment is one theory, they come straight out of the chalk this way no weathering, they are pretty fragile.