Wear Patterns on Mosasaur Teeth

[LordTrilobite]

I like Mosasaurs so I've been buying some cool stuff here and there for a while now. I have some loose teeth with and without roots and a few jaws. for a while now I've been noticing some interesting patterns. Or rather a single pattern that keeps showing up. I have 42 loose teeth and a number of these teeth have some wear patterns on them. Some just have some random wear here and there or tips broken or worn off of them. But a significant number of teeth have damage to the enamel on the front side of the tooth. Sometimes on the lateral side and sometimes on the labial side. Sometimes on both sides. Of these 42 teeth, 13 have significant damage to the enamel on the front. In about 8 or so the pattern is quite similar. This pattern seems almost exclusive to the large Prognathodon teeth with the only exception being a Mosasaurus beaugei? tooth that has some wear on the front. Though this tooth isn't nearly as damage on the front as the big Prognathodon teeth. This same wear pattern also shows up on a Prognathodon jaw that I'm still prepping. This jaw shows the same damage while the teeth are still mostly in the original position aside from some minor drifting. This pattern also does not show in the jaws of other mosasaur species I have.
 

 

So I'm wondering is if this could possibly be as a result of some behaviour that Prognathodon might have had. Since quite a lot of the teeth show the same type of damage and it also shows in still rooted teeth. Have any of you ever seen this same pattern on mosasaur teeth? I'm wondering what your opinions are on this.

 

 

My loose mosasaur teeth, one not shown. Big Prognathodon teeth at the top. Some possible Eremiasaurus teeth below them. The small recurved tooth crown on the left is Halisaurus arambourgi. Below it two small Platecarpus ptychodon teeth. Under those two badly crushed teeth. Lower left middle Mosasaurus teeth, some probably M. beaugei and some M. hoffmanni. Globidens teeth at the bottom. Prognathodon, Mosasaurus and Globidens rooted teeth on the left.

 

Teeth with damage on the front. Only three that aren't Prognathodon at the bottom.

 

Detail of a Prognathodon tooth.

 

Prognathodon jaw with the same type of enamel damage on three teeth. The teeth towards the front are too damage during the fossilisation to tell if they have similar damage.

[Troodon]

Interesting subject which I cannot add to the conversation but here is a paper I came across not sure if it's of any use.

 

url.html   

[HamptonsDoc]

Could it be from the opposite tooth above biting down into it? Just a guess. 

[sixgill pete]

Very interesting topic. Looking at the one measly mosasaur tooth I have from the PeeDee of N.C. I see a similar wear of enamel also.

[doushantuo]

Just spitballing: you found any evidence for a correlation with age,size,or position in the jaw?

Does it occur,e.g. only in loose teeth?

If incomplete resorption of the cementum takes place during ontogeny,the dentine enamel surface might be vulnerable,particularly in a durophagous predator

[JohnJ]

I'll play skeptic. 

 

We have to ask, what evidence is there that this damage was done while the mosasaur was alive?  There are many possibilities that it could be attributed to other than damage during life. 

 

Given how notoriously fragile mosasaur teeth can be, it could be something as simple as the curved shape of the tooth contributing to these damaged areas.  Note that the 'crazing' (micro cracks) in the surface layers of these teeth creates areas more susceptible to weakness on the outer curves of a tooth.  The web of cracking along the outside curved surface provides less support for the isolated 'flakes' of the tooth's surface. The flakes of those outside curve cracks are influenced to a greater degree by expansion and contraction.  Whether a tooth is rooted, or not, it is still easier for these outer curved surfaces to have these flakes pop off because they don't have the cradled support of an inner curve.

[sixgill pete]

9 hours ago, JohnJ said:

I'll play skeptic. 

 

We have to ask, what evidence is there that this damage was done while the mosasaur was alive?  There are many possibilities that it could be attributed to other than damage during life. 

 

Given how notoriously fragile mosasaur teeth can be, it could be something as simple as the curved shape of the tooth contributing to these damaged areas.  Note that the 'crazing' (micro cracks) in the surface layers of these teeth creates areas more susceptible to weakness on the outer curves of a tooth.  The web of cracking along the outside curved surface provides less support for the isolated 'flakes' of the tooth's surface. The flakes of those outside curve cracks are influenced to a greater degree by expansion and contraction.  Whether a tooth is rooted, or not, it is still easier for these outer curved surfaces to have these flakes pop off because they don't have the cradled support of an inner curve.

 

Absolutely not John.  As far as the tooth I have it was found in a stream environment so anything could have caused the damage. I just find it interesting that these teeth show similar wear. Your thought on the weakness of the outer curve is, at least to me valid. I would love to hear from others who have mosasaur teeth from other areas to see if their teeth exhibit this same wear. 

[LordTrilobite]

12 hours ago, HamptonsDoc said:

Could it be from the opposite tooth above biting down into it? Just a guess. 

That thought had crossed my mind as well. There are definitely other reptile teeth that have wear from the opposite tooth. but those tend to create flat facets on the side where the teeth meet rather than more "ugly" damage. Take this Tyrannosaurid tooth for example. It has two clear wear facets due to occlusion wirrth other teeth. These surfaces are prettty flat and "clean" compared to the enamel damage on the mosasaur teeth presented in this thread.

 

 

12 hours ago, sixgill pete said:

Very interesting topic. Looking at the one measly mosasaur tooth I have from the PeeDee of N.C. I see a similar wear of enamel also.

Could you share a photo perhaps? Any idea of the species?

 

9 hours ago, doushantuo said:

Just spitballing: you found any evidence for a correlation with age,size,or position in the jaw?

Does it occur,e.g. only in loose teeth?

If incomplete resorption of the cementum takes place during ontogeny,the dentine enamel surface might be vulnerable,particularly in a durophagous predator

 

9 hours ago, JohnJ said:

I'll play skeptic. 

 

We have to ask, what evidence is there that this damage was done while the mosasaur was alive?  There are many possibilities that it could be attributed to other than damage during life. 

 

Given how notoriously fragile mosasaur teeth can be, it could be something as simple as the curved shape of the tooth contributing to these damaged areas.  Note that the 'crazing' (micro cracks) in the surface layers of these teeth creates areas more susceptible to weakness on the outer curves of a tooth.  The web of cracking along the outside curved surface provides less support for the isolated 'flakes' of the tooth's surface. The flakes of those outside curve cracks are influenced to a greater degree by expansion and contraction.  Whether a tooth is rooted, or not, it is still easier for these outer curved surfaces to have these flakes pop off because they don't have the cradled support of an inner curve.

It's certainly good to remain skeptical. I don't want to draw and conclusions myself I just think that there seems to be a pattern that warrants some investigation.

 

From what I can tell this type of damage seems most common in the Prognathodon teeth, especially the larger ones. Some of the smaller Prognathodon teeth also have it but it seems less common. Of course a larger sample size would always be better. At first I also thought just the obvious damge on the exposed rounded side would be fairly obvious when a loose tooth is tumbling around in the water before it is burried and fossilises. But the Prognathodon jaw with three teeth roughly in life position that show the same damage could suggest this type of damage might have happened during the life of the animal. Though if it happened during life, it's worth noting that Globidens does not show the same kind of damage, which is another durophagous mosasaur. At least not to my knowledge.

 

Does anyone know what kind of damage bone crushing does to teeth?

 

[doushantuo]

i think what we can conclude right away is: 25% percent of the teeth having this frontal enamel damage is a statistically significant number.

Don't ask me why() but i have faith in your taxonomic asessment.

so 25 percent of Prognathodon tooth show this.

edit:

which reminds me:

 

2013_Houssaye&Bardetjuvontogen_TethysaurusJr.pdf

[LordTrilobite]

On 11/4/2016 at 3:34 PM, doushantuo said:

i have faith in your taxonomic asessment

I'm by no means an expert. I would say I can recognise the larger Prognathodon teeth pretty well as well as Halisaurus and Platecarpus teeth. Those have some clear morphology. Mosasaurus and Eremiasaurus are harder I find harder to identify. And according so some Tylosaurus is also present in Morocco. But I have no experience with that species. Even though I might have one in this collection of teeth.

 

I forgot about some other mosasaur material I have that also shows this wear pattern. And I'll also include my remaining mosasaur material for statistics sake. So here are some more photos.

 

Prognathodon teeth with some possible jaw fragments. Probably my best really large Prognathodon tooth. And it also shows the same pattern. Interestingly there's two small mosassaur teeth in the same block. And one of them also shows the same pattern. Which is probably the smallest tooth with that pattern I have. It also looks like Prognathodon due to the shape and smooth enamel.

 

A loose tooth I forgot to add to the lot. Minor damage on the front but it seems vaguely similar. Mosasaurus beaugei maybe?

 

Large Prognathodon tooth. Same damage pattern. Though not very visible in these photos.

 

 

 

A rather nice partial maxilla of Mosasaurus, possibly M. beaugei. While not the same pattern, it does show identical wear on both complete teeth on the front. These look like the tips of the opposite teeth might have worn those areas. But that's just a guess.

 

 

 

Mosasaurus (M. hoffmanni?) jaw fragments with two teeth. No significant damage on the enamel.

 

Huge Prognathodon partial pterigoid. I've restored the one front tooth but it probably does belong to the jaw. The front tooth shows some tiny amount of enamel damage that looks similar to the wear pattern seen in the other Prognathodon teeth. The tooth in the back is missing a large portion of the tip but does not show any damage to the enamel.

 

Prognathodon jaw fragments and two teeth. The complete tooth shows minor damage to the front.

 

juvenile? Prognathodon lower jaw. Aside from the missing parts no damage that seems relevant.

 

 

Halisaurus walkeri lower jaw fragment. These are the teeth furthest back in the jaw. There is damage but it looks more random. I don't think this one is relevant.

Maxilla of Halisaurus arambourgi. Aside from the missing tooth tips there does seem to be some random damage to the enamel. No visible pattern.

 

 

 

And I forgot to photograph three remaining mosasaur teeth I have. A globidens tooth, Prognathodon tooth and a Platecarpus ptychodon tooth fragment. None of these show relevant damage.

 

 

 

 

[LordTrilobite]

This should include my entire Mosasaur collection. I'm just counting teeth here. this includes the individual teeth that are still in jaws. I have not included teeth that are less than half complete as I could not get any information out of those. Although I know some of my teeth are Mosasaurus beaugei and some Mosasaurus hoffmanni. I'm not certain about the majority of them so I'm bunched them together as Mosasaurus sp.

 

So here's some number crunching.

 

Tooth crowns
Prognathodon sp.
17

Eremiasaurus or Prognathodon
8

Mosasaurus sp.
9

Globidens sp.
5

Platecarpus ptychodon
3

Halisaurus arambourgi

1

indet.
2

Total 45

 

Rooted teeth
Prognathodon sp.
2

Mosasaurus sp.
1

Globidens sp.
1

Total 4

Teeth in jaws or jaw fragments
Prognathodon sp.
8

Mosasaurus sp.
3

Halisaurus walkeri
3

Halisaurus arambourgi
3

Total 17

 

 

Teeth with longitudinal damage to the front of tooth
Prognathodon sp.
16

Mosasaurus sp.
3

Total 19

Teeth with round facet damage to the front of tooth
Prognathodon sp.
2

Mosasaurus sp.
2

Total 4

Teeth with random or no significant damage.
Prognathodon sp.
9

Eremiasaurus or Prognathodon
8

Mosasaurus sp.
8

Platecarpus ptychodon
3

Halisaurus walkeri
3

Halisaurus arambourgi
4

Globidens sp.
6

Indet.
2

Total 43

 

 

Total by genus and species

Prognathodon sp. total

27

Eremiasaurus or Prognathodon total
8

Mosasaurus sp. total

13

Globidens sp. total

6

Halisaurus walkeri total

3

Halisaurus arambourgi total

4

Platecarpus ptychodon total

3

Indet.

2

Total teeth 66

 

 

So this would mean that:

28.7% of all my 66 mosasaur teeth have the same longitudinal damage to the front of the teeth.

59.2% of my 27 Prognathodon sp. teeth have longitudinal damage to the front.

23% of my 13 Mosasaurus sp. teeth have longitudinal damage to the front. I think these might be M. beaugei, but I'm not sure.

 

7.4% of my Prognathodon sp. teeth have circular wear facets.

15.3% of my Mosasaurus sp. teeth have circular wear facets.

 

33.3% of my Prognathodon sp. teeth have random or no significant damage.

61.5% of my Mosasaurus sp. teeth have random or no significant damage.

 

Note that 0% of the teeth that could be either Eremiasaurus or Prognathodon have damage. So this could possibly bring the damage percentage on Prognathodon down a bit.

 

So almost 60% of my Prognathodon teeth show the same pattern. But due to the small sample size please take this with a massive grain of salt. Still, I think these are some interesting results.

 

[doushantuo]

uhm ,see if i can find something else besides this.

I haven't sorted my odontology PDF's yet(at least not to my complete satisfaction

"Regardless of possible difficulties with deformation and lateral
forces pushing the dentition apart, many carnivorous animals
succeed in fragmenting tough prey with bladed dentitions. Although
the jaws and dental surfaces themselves probably do not bend (the
gnathostome jaw is stiffer than the thin blades used in this study),
given the typically large mobility of the jaw joint, animals trying
to cut tough prey materials must find some way to prevent tough
materials (like salmon muscle) from pushing the dental surfaces out
of alignment. The results of this study show that simply having
irregular shaped bladed dentition can allow for fracture to occur at
lower strain levels, and eliminate a good deal of the deformation
that causes these problems. The relief angle of a tooth, defined as
the angle between the movement of the tool and its trailing edge
(called clearance in the engineering literature), can work to prevent
teeth from being separated by food (Evans and Sanson, 2003)."

(JEXPB,2008,Anderson/LaBarbera)

 

Andersonenamelodontolrayfieldal2011.pdf

[doushantuo]

I regret having read too little of my vertebrate odontology lit

This might be relevant

davitbealsireodontolteethenameltetrapobjoa0214-0477.pdf

also thinking of Fanti/Cau

https://www.researchgate.net/profile/Federico_Fanti/publications?pubType=article