Hollow Shark Teeth

[Bill]

It has been stated on another forum I belong to, that the hollow shark teeth often found, are immature teeth and that they start off as hollow crowns, which then fill as they mature. I personally don't buy this, any opinions? As an example a 1 5/8" meg tooth, hollow crown, has been figured.

Here

[Northern Sharks]

Seeing as that is my tooth, you already know my opinions on it. I should also mention that a similar tooth is shown in Mark Renz's book Megalodon, Hunting the Hunter (pg. 84)

[Bill]

Hi Northern Sharks.

The trouble is, for me, I have found hollow teeth at Sheppey, Bracklesham Bay, Walton and Abbey Wood. They were the same size as the complete teeth, which were about average size, to recorded max, for the sp. I have also found complete teeth, with roots, from these sites, where the 'enamel' is coming away from the 'dentine'. Just looking for more input on the subject.

[tracer]

the "immature teeth" explanation goes against what i've read regarding the formation of enamel.

amelogenesis must be preceded by dentinogenesis, to my understanding.

i would think the explanation could be more along the lines of differential erosion or decomposition, at least to the degree of the dentin somehow becoming detached from the enamel rods. an analogy for illustration purposes but not grounded in physical science would be the way hoofs and claws end up separated from their cores.

enamel is much more highly mineralized than the rest of the body's hydroxylapatitic (i made up the adjective from the noun. forgive me, but you should be used to it by now. and sorry, too, for the distracting parenthetical expressions. [i didn't make up "parenthetical"]) structures, which is why teeth are often the only things found, and teeth without roots are common.

[mommabetts]

I don't buy it being immature teeth, haven't run across that explanation. With the way teeth are formed, it doesn't seem possible to me.

[tracer]

i just noticed that mommabetts, one minute before me, posted a two-liner saying what i said, only much more to the point and understandable. were i such a poster, mine would have been up first, and i would have won. let that be a lesson to you young people out there. traceresquenessitudinous verbosity has other disadvantages besides failure to eschew obfuscation.

[Northern Sharks]

http://www.elasmo.com/cunningham/c_taurus/sc_ct-discuss.html

Hopefully this helps as well

[Bill]

Cheers, Northern

It does to a degree. I may have misread it but, lack of root structure doesn't, to me, mean hollow teeth, only rootless ones.

EDIT very interesting, nevertheless

[Northern Sharks]

http://deepblue.lib.umich.edu/bitstream/20...502/2/ID353.pdf

Here's another from the University of Michigan. Go down to pg7 of 14 (or pg 251 in the article)

[Harry Pristis]

In vertebrate teeth, the enamel (or enameloid) is always formed first. As the cycle of growth/replacement progresses, the roots (dentin) form.

A hollow crown of shark enameloid is always present in some position(s) in the shark tooth file, even in the largest megalodon. These shells are not as readily preserved as a fully-developed tooth. These shells are homologous to an unerupted mastodon "tooth cap" or to a tooth cap from any other vertebrate.

I think Gordon Hubbell has a set of associated meg teeth--large ones--that was collected by Larry Martin. (I saw them at Larry's house, not Gordon's.) This set has both the fully developed teeth and the enameloid shells that were the developing replacements.

You can learn more about this process on pp. 82 of MEGALODON: HUNTING THE HUNTER by Mark Renz. If you think of yourself as even a casual collector of shark teeth, you need this book. It's a better than average guide with fabulous images (you can see a picture of my hand). Coverage is much broader than megalodon. I vouch for the readability because I helped Mark edit his book.

[THobern]

You shouldn't assume that it must be one explanation or the other. From what I've read about removing modern teeth from jaws, the roots form after the enamel and you will indeed find "hollow teeth". This does not, however, mean that all hollow teeth are immature, as while some may indeed be immature, some may have simply broken. I'm guessing that, 9 times out of 10, hollow fossil teeth are simply broken teeth. I've found dozens, literally, of hollow teeth at Walton, and it's fairly obvious that most of them were simply broken.

I don't follow the argument that teeth cannot be immature, because they are the size of formed teeth. Teeth are forming continuously, and if the enamel does form first, it should be the same size as a formed tooth. "Immature" refers to the development of the tooth, not of the shark.

[Bill]

Ok Northern, you win.

Hi Thobern, that would mean that the less developed hollow teeth, in the last file or two/three, would be the same size as those in the front files. Don't the teeth get progressively larger toward the front file?

Edited.

[tracer]

i noted in one of the references that it referred to "vitrodentine" as an analog of enamel. it may be that shark tooth formation is somehow different from what i've read elsewhere regarding "regular" enamel formation on teeth. don't know. may research later. may not. <snoopy dancing while my teeth rot>

(p.s. - just kidding. bi-annual visits to le dentiste are de rigeur)

)p.p.s. - it's hard to sound smart sometimes. did i spell that french stuff right?{

[THobern]

You shouldn't assume that it must be one explanation or the other. From what I've read about removing modern teeth from jaws, the roots form after the enamel and you will indeed find "hollow teeth". This does not, however, mean that all hollow teeth are immature, as while some may indeed be immature, some may have simply broken. I'm guessing that, 9 times out of 10, hollow fossil teeth are simply broken teeth. I've found dozens, literally, of hollow teeth at Walton, and it's fairly obvious that most of them were simply broken.

I don't follow the argument that teeth cannot be immature, because they are the size of formed teeth. Teeth are forming continuously, and if the enamel does form first, it should be the same size as a formed tooth. "Immature" refers to the development of the tooth, not of the shark.

Nope. From what I understand, they develop from the tip to the base. But you should remember that a tooth is enamel. It can't "grow". If a tooth were to begin as a formed, but smaller, version of the mature teeth, how could it grow larger as it progressed farther up the jaw?

[tracer]

ok, i was misled a bit, i think, by limited reading before. although i think i correctly stated that enamel forms on dentin, that doesn't mean that all dentin, (ie complete root) is present before the crown. here's a fairly terminology-laden explanation that describes the process.

i went through all this just to chew?

[Harry Pristis]

This thread is suffering from an imprecision of language. "Front file" can only mean the stack of teeth, from germ-tooth to tooth-in-battery, at the anterior position on the jaw. This is a vertical stack, as the fish swims.

With this understood, yes, as long as the shark is growing, you could expect the crown of a germ teeth to be slightly larger than its predecessors in the same anlage or file. But, that fact is irrelevant.

[Frank Menser]

Interesting thread!

I have found several sand mako teeth at the pond that are hollow, all under an inch. None have roots. Oddly the enamel is almost plastic like in its flexibility.

[cat shark]

Interesting thread!

I have found several sand mako teeth at the pond that are hollow, all under an inch. None have roots. Oddly the enamel is almost plastic like in its flexibility.

I have found hollow teeth from several different sites. All of them have enamel like that?

[siteseer]

Yes, it all starts by looking at a set of modern jaws. If you take one apart, you will find just "husks" without roots. Also, remember that mammal teeth have enamel, while sharks have enameloid - close to enamel but not exactly the same.

I remember Bruce Welton, back in the early 90's, once pointed out to me a large Early Eocene matrix piece from Morocco with several Otodus teeth in it. He showed me the crowns that appeared to be just broken teeth but were actually teeth that were in an early stage of development. He said that's the kind of matrix piece he looks for because it could bear a partial dentition in it.

You shouldn't assume that it must be one explanation or the other. From what I've read about removing modern teeth from jaws, the roots form after the enamel and you will indeed find "hollow teeth". This does not, however, mean that all hollow teeth are immature, as while some may indeed be immature, some may have simply broken. I'm guessing that, 9 times out of 10, hollow fossil teeth are simply broken teeth. I've found dozens, literally, of hollow teeth at Walton, and it's fairly obvious that most of them were simply broken.

I don't follow the argument that teeth cannot be immature, because they are the size of formed teeth. Teeth are forming continuously, and if the enamel does form first, it should be the same size as a formed tooth. "Immature" refers to the development of the tooth, not of the shark.

[siteseer]

Yes, the tooth buds are rather soft. That's when they are especially vulnerable to damage or displacement. Some of the fossil "pathologic" teeth are actually those that were damaged or deflected as they were developing. A tooth file can continually generate deformed teeth if a stingray barb or other foreign object remains stuck in the jaw where teeth are maturing.

Interesting thread!

I have found several sand mako teeth at the pond that are hollow, all under an inch. None have roots. Oddly the enamel is almost plastic like in its flexibility.

[Paleoc]

Ok Northern, you win.

Hi Thobern, that would mean that the less developed hollow teeth, in the last file or two/three, would be the same size as those in the front files. Don't the teeth get progressively larger toward the front file?

Edited.

Each replacement tooth in a shark's jaw is slightly larger than the tooth in front of it which it is replacing. Which makes sense if you think about it. As the shark grows larger, its teeth get larger, thus the replacement (newer tooth) is going to be larger than its predecessor. Replacement teeth as you go further back into the gum have less and less root, are more and more hollow and the enamel is more and more spongy and chalky. In life they are probably filled with blood and tissue to grow the tooth.

I have about 200+ shark jaws of about 120+ species, so I am pretty confident of what I am talking about here.

Hollow fossil teeth are often replacement teeth although in some locations due to acidity or some other factor cause teeth to be poorly fossilized and thus hollow and rootless. I have collected where virtually all the small teeth were rootless and often hollow while large teeth were usually well preserved.

[bear-dog]

My understanding on these teeth were they were still in the shark at the time of death.The decomp.caused it before any fossilization began

[Harry Pristis]

In vertebrates, including sharks, tooth enamel (enameloid in sharks) is laid down first, then dentin (dentine in sharks), then (in mammals) cementum.

Some of these shark teeth with no trace of dentin inside the enamel are "enamel caps" which were never in battery in the sharks mouth. These are homologous to the mastodon or tapir enamel caps which are often well-preserved because they are thick enamel compared with a shark tooth. An enamel cap should be without wear because it has not moved into battery (or erupted in the case of non-sharks).

With that understanding, you can argue about the nature of individual teeth.

Edited August 12, 2010 by Harry Pristis