Mosasaur tooth crowns ID

[Mochaccino]

Hello,

 

Thanks so much everyone @Troodon @pachy-pleuro-whatnot-odon @Praefectus for your help with the mosasaur jaws last time. I was wondering if you could help ID the following teeth crowns? They're said to be from the Atlas mountains of northern Africa. I feel like there's quite some variation but I can't tell if that's just due to heterodonty or a difference in genus/species. Or perhaps as I found out last time, some of these are "throat teeth"?

 

Lot 1.

 

 

Lot 2.

 

Lot 3.

 

Thank you!

[Troodon]

These mosasaur teeth are from the phosphate beds of the Ouled Abdoun Basin of Morocco.  I'll let others ID them for you

[Praefectus]

Left: Mosasaurus beaugei

The tall crown with numerous lingual facets are diagnostic of M. beaugei. 

 

Right: Prognathodon sp. nov. (=Leiodon anceps)

This is a posterior Prognathodon tooth crown from the species informally called "Prognathodon anceps." The species is currently undergoing a re-naming and redescription. Flutes are not present on Prognathodon currii or Prognathodon giganteus. They are much more pronounced on P. solvayi. 

 

 

Left: Prognathodon sp. nov. (=Leiodon anceps)

Anterior tooth. 

 

Right: Indeterminate from pictures provided. 

I need to see this one from a few more angles. Clear pictures showing the labial, lingual, anterior, posterior, and basal views. Currently, I am split between Moroccan tylosaur (more common) and Mosasaurus hoffmannii (less common). The way to differentiate them would be based on direction of recurvature (posterior = tylosaur, medial = M. hoffmannii), presence of surface facets (labial ridges = tylosaur, flat facets = M. hoffmannii), and basal cross-section (oval = tylosaur, U-shape = M. hoffmannii). 

 

 

Left: Mosasaurus beaugei

Prominent medial curvature is a giveaway for Mosasaurus. 

 

Right: Prognathodon sp. nov. (=Leiodon anceps). 

This is the most common species in the Phosphates. Its thick enamel is iconic. 

[Praefectus]

58 minutes ago, Mochaccino said:

They're said to be from the Atlas mountains of northern Africa. I feel like there's quite some variation but I can't tell if that's just due to heterodonty or a difference in genus/species. Or perhaps as I found out last time, some of these are "throat teeth"?

 

The teeth all originate from the Phosphate quarries near Oued Zem, Morocco. All the teeth above are marginal teeth from the jaws (not second-row pterygoid teeth). 

[pachy-pleuro-whatnot-odon]

I'll forgo on telling you these teeth are not from the Atlas mountains, as this has already been mentioned above. When it comes to identification too, I mostly agree with what Trevor has said, except for the teeth in the second set, which I believe could be Eremiasaurus heterodontus, which anterior teeth may be slightly prismatic and only have a single anterior carina. In any case, I see neither tylosaur nor M. hoffmannii in the specimen to the right in that batch. But, as Trevor said, better photographs are needed to determine what these teeth actually are.

 

As an aside, I'd furthermore just identify the right tooth of the first batch as generic Prognathodon sp. (without associating it with the former Leiodon anceps), as I think the tooth shows more affinity to P. solvayi, even if bid species hasn't officially been described from Morocco yet...

Edited March 7, 2022 by pachy-pleuro-whatnot-odon
Corrected mistaken statement on Eremiasaurus heterodontus having only a posterior carina, which should be anterior.

[Praefectus]

5 minutes ago, pachy-pleuro-whatnot-odon said:

Eremiasaurus heterodontus

Right tooth or left tooth? I could see the left tooth being Eremiasaurus too. I couldn't make out that the posterior carina might be missing. 

 

8 minutes ago, pachy-pleuro-whatnot-odon said:

As an aside, I'd furthermore just identify the right tooth of the first batch as generic Prognathodon sp. (without associating it with the former Leiodon anceps), as I think the tooth shows more affinity to P. solvayi, even if bid species hasn't officially been described from Morocco yet...

Maybe? The P. solvayi holotype teeth don't curve medially and have flutes more closely spaced. Prognathodon sp. nov. (=L. anceps) is noted as sometimes having enamel flutes. 

 

 

[pachy-pleuro-whatnot-odon]

8 minutes ago, Praefectus said:

Right tooth or left tooth? I could see the left tooth being Eremiasaurus too. I couldn't make out that the posterior carina might be missing.

 

I'm thinking both teeth could be possible, but the right one in particular. As noted, Eremiasaurus-teeth can be somewhat prismatic in appearance, and the overall outline of both teeth matches what may be expected for E. heterodontus. However, determination of which carinae are present is needed to confirm this. I can see the left tooth being a prognathodontid, but think the tooth on the right is too faceted to match M. hoffmannii. At the same time, the ornamentation of this tooth does remind me of faceting rather than tertiary striae, which would rule out tylosaurine.

 

8 minutes ago, Praefectus said:

Maybe? The P. solvayi holotype teeth don't curve medially and have flutes more closely spaced. Prognathodon sp. nov. (=L. anceps) is noted as sometimes having enamel flutes.

 

Yeah, in my opinion, this is kind of where you run into issues with assigning labels to isolated teeth, as P. anceps has indeed been noted to sometimes have "fluted"/faceted teeth (I'll refer to your own extremely useful analysis of the literature), yet there seems to be a lot of mix-up concerning the description of prognathodontid teeth from Morocco that aren't P. currii. To me this means that, unless the teeth were found in clear association (i.e., attached) with identifiable skeletal remains, it remains possible for isolated teeth to have been wrongly identified. The matter needs further analysis. The particular tooth under discussion here (right, 1st batch), though, would, I believe, not be out of place for P. solvayi. having seen the type-specimen myself (and still having a bunch of photographs for reference). Much like other prognathodontids, both this tooth and the teeth of P. solvayi have mesial curvature, while both have a comparable degree of lateral compression, density of facets, and curvature. Likewise, one of the few/only positively identified candidates for an isolated Moroccan P. solvayi has durophagous adaptations, much like regular prognathodontids. Again, the matter deserves further study, but hence my observation that OP's tooth morphologically seems a closer match to P. solvayi than to P. anceps to me...

[Mochaccino]

@Troodon @Praefectus @pachy-pleuro-whatnot-odon

 

Thanks all! I wonder why the seller listed the locality as such, I'm only aware of the moroccan teeth so I also thought these looked like them as well. As for the ID, I think I'm starting to see the characteristics you point out. The Prognathodon's thick enamel is essentially the gradient of darkening towards the apex, which is not present in the left teeth of batches 1 and 3. Speaking of those teeth, for Mosasaurus I can also see that the teeth are elongated, lack the gradient of the thick enamel, and have many "ridges" or facets as you described. By medial curvature it seems you mean they curve towards the tongue and center of the mouth. Very cool and informative.

 

I'm more lost on the second batch coming down to species identification but from searching other posts on this forum, it's mentioned that Tylosaur teeth are almost straight all the way, then at the tip have a sharp backwards curvature (as opposed to medially as in Mosasaurus); is this accurate? I want to see if I can find some of the rarer species' teeth for sale, such as Tylosaur or M. hoffmannii as you mentioned.

 

 

 

 

Edited March 8, 2022 by Mochaccino

[pachy-pleuro-whatnot-odon]

5 hours ago, Mochaccino said:

Thanks all! I wonder why the seller listed the locality as such, I'm only aware of the moroccan teeth so I also thought these looked like them as well.

 

Yeah, I don't quite get it either. Could be that the seller is just entirely unaware; is trying up his merchandise's value by listing them as having come from an unusual location; or wants to ride on the popularity of the dinosaur finds made in the Atlas. Personally, though, I expect it's a bit of all three, where the seller might not be fully aware of what he's selling or where it actually comes from, but has heard some popular terms mentioned that they're now using to make their product sound more interesting than it is. This, I think, is a strategy that works best on, and is therefore most likely intended for, the less savvy beginner or sporadic collector. This, to me, is something evidenced from the merchandise itself as well, as these would not be the material that would attract the more experienced collectors...

 

Quote

As for the ID, I think I'm starting to see the characteristics you point out. The Prognathodon's thick enamel is essentially the gradient of darkening towards the apex, which is not present in the left teeth of batches 1 and 3. Speaking of those teeth, for Mosasaurus I can also see that the teeth are elongated, lack the gradient of the thick enamel, and have many "ridges" or facets as you described. By medial curvature it seems you mean they curve towards the tongue and center of the mouth. Very cool and informative.

 

Yup, you seem to have picked up on all points perfectly! Only I wouldn't necessarily say Mosasaurus-teeth are more elongated, as this does somewhat depend on position along the jaw. As a general trend, however, they are more laterally compressed/slender and somewhat less wide than most prognathodontid teeth

 

As to the medial curvature: the term "medial" can be offset to the term "lateral", the former meaning the direction towards the axial skeleton (i.e., the midline of the body in bilateria) and the later pointing exactly in the opposite direction. See the diagram below (source) to help you orientate, but ignore the terms "anterior", "posterior", "inferior" and "superior", as these aren't skeletal directions persé, but rather refer to the positioning of a body in three dimensional space (i.e., "to the front", "to the back", "to the bottom", and "to the top" respectively; I'm sure I had a better and less homocentric diagram at one point, but can't seem to find it back).

 

 

With respect to the medial curvature mentioned, "towards the midline" would indeed equate to "lingual". However, slightly different terminology is in use to describe orientation in the mouth, where dental arches, in effect, form a curved continuum. Here, where anterior and medial directions may lead to the same point along the jaw, the term "mesial" is used to denote the anterior portion of the mouth, "lingual" to denote the centre of the mouth, leaving "medial" reserved for combination-terms, such as "mediodistally" (at one time lingually and distally) - presumably as "linguodistally" just doesn't sound as good (though the term is, in fact, used as well). See the diagram below (source) for reference. Teeth of the genus Mosasaurus are therefore, in reality, mediodistally rather than simply medially curved

 

 

Quote

I'm more lost on the second batch coming down to species identification but from searching other posts on this sub, it's mentioned that Tylosaur teeth are almost straight all the way, then at the tip have a sharp backwards curvature (as opposed to medially as in Mosasaurus); is this accurate? I want to see if I can find some of the rarer species' teeth for sale, such as Tylosaur or M. hoffmannii as you mentioned.

 

Yes, Moroccan tylosaurine teeth are quite laterally compressed with apical curvature and carinae along the mesiodistal plane. They may also have striae along the base. I'd say the jury is still out on whether they can be ascribed to Tylosaurus or whether they align more closely to what used to be known as Hainosaurus (which has since become conflated with Tylosaurus). Mosasaurus hoffmannii is a tricky one to find, as it's hard to identify, especially just from photographs. Your best bet is to look through teeth that have the Mosasaurus-morphology, such as M. beaugei -i.e., check for mediodistal curvature, unequal cross-section at the base with a flat labial face. Then, if you can barely make out prismatism and facets, that's when you can be pretty certain you've found a M. hoffmannii.

 

Good luck hunting! 

[Mochaccino]

20 hours ago, pachy-pleuro-whatnot-odon said:

 

Yeah, I don't quite get it either. Could be that the seller is just entirely unaware; is trying up his merchandise's value by listing them as having come from an unusual location; or wants to ride on the popularity of the dinosaur finds made in the Atlas. Personally, though, I expect it's a bit of all three, where the seller might not be fully aware of what he's selling or where it actually comes from, but has heard some popular terms mentioned that they're now using to make their product sound more interesting than it is. This, I think, is a strategy that works best on, and is therefore most likely intended for, the less savvy beginner or sporadic collector. This, to me, is something evidenced from the merchandise itself as well, as these would not be the material that would attract the more experienced collectors...

 

 

Yup, you seem to have picked up on all points perfectly! Only I wouldn't necessarily say Mosasaurus-teeth are more elongated, as this does somewhat depend on position along the jaw. As a general trend, however, they are more laterally compressed/slender and somewhat less wide than most prognathodontid teeth

 

As to the medial curvature: the term "medial" can be offset to the term "lateral", the former meaning the direction towards the axial skeleton (i.e., the midline of the body in bilateria) and the later pointing exactly in the opposite direction. See the diagram below (source) to help you orientate, but ignore the terms "anterior", "posterior", "inferior" and "superior", as these aren't skeletal directions persé, but rather refer to the positioning of a body in three dimensional space (i.e., "to the front", "to the back", "to the bottom", and "to the top" respectively; I'm sure I had a better and less homocentric diagram at one point, but can't seem to find it back).

 

 

With respect to the medial curvature mentioned, "towards the midline" would indeed equate to "lingual". However, slightly different terminology is in use to describe orientation in the mouth, where dental arches, in effect, form a curved continuum. Here, where anterior and medial directions may lead to the same point along the jaw, the term "mesial" is used to denote the anterior portion of the mouth, "lingual" to denote the centre of the mouth, leaving "medial" reserved for combination-terms, such as "mediodistally" (at one time lingually and distally) - presumably as "linguodistally" just doesn't sound as good (though the term is, in fact, used as well). See the diagram below (source) for reference. Teeth of the genus Mosasaurus are therefore, in reality, mediodistally rather than simply medially curved

 

 

 

Yes, Moroccan tylosaurine teeth are quite laterally compressed with apical curvature and carinae along the mesiodistal plane. They may also have striae along the base. I'd say the jury is still out on whether they can be ascribed to Tylosaurus or whether they align more closely to what used to be known as Hainosaurus (which has since become conflated with Tylosaurus). Mosasaurus hoffmannii is a tricky one to find, as it's hard to identify, especially just from photographs. Your best bet is to look through teeth that have the Mosasaurus-morphology, such as M. beaugei -i.e., check for mediodistal curvature, unequal cross-section at the base with a flat labial face. Then, if you can barely make out prismatism and facets, that's when you can be pretty certain you've found a M. hoffmannii.

 

Good luck hunting! 

 

Got it! Thank you again for the detailed anatomy lessons. I think I understand the confusion about anterior/posterior and inferior/posterior, as humans are generally depicted completely upright and belly (ventral) facing forwards due to being bipedal, in a different general orientation to many vertebrates (such as the mosasaur of course).

 

Also much learned about dental anatomy. So Mosasaurus would have mediodistally/linguodistally curved teeth (towards the center of the mouth and pointing backwards), whereas Tylosaur would have simply distally curved teeth (pointing straight backwards) with the curvature starting close to the tip (aka "apical curvature"). And for Mosasaurus hoffmani that "unequal cross-section at the base with a flat labial face" must be what @Praefectus was talking about with the U-shaped cross-section, essentially that the tooth isn't completely round/conical but has a flat face at the side pointing away from the tongue. Though this is probably going to be harder to check especially just based on seller-provided photos. As for "prismatism and facets", is it the angular, polygonal look such as what this tooth explicitly identified as M. hoffmanni has towards the base of its labial surface?:

 

 

 

In any case many thanks! It should be a fun "hunt" to see if I can identify these species. It seems M. hoffmanni and Tylosaur are some of the rarer ones; are there any more rare species I could look out for?

Edited March 9, 2022 by Mochaccino

[pachy-pleuro-whatnot-odon]

2 hours ago, Mochaccino said:

Got it! Thank you again for the detailed anatomy lessons. I think I understand the confusion about anterior/posterior and inferior/posterior, as humans are generally depicted completely upright and belly (ventral) facing forwards due to being bipedal, in a different general orientation to many vertebrates (such as the mosasaur of course).

 

Also much learned about dental anatomy. So Mosasaurus would have mediodistally/linguodistally curved teeth (towards the center of the mouth and pointing backwards), whereas Tylosaur would have simply distally curved teeth (pointing straight backwards) with the curvature starting close to the tip (aka "apical curvature"). And for Mosasaurus hoffmani that "unequal cross-section at the base with a flat labial face" must be what @Praefectus was talking about with the U-shaped cross-section, essentially that the tooth isn't completely round/conical but has a flat face at the side pointing away from the tongue. Though this is probably going to be harder to check especially just based on seller-provided photos.

 

Yeah, you totally nailed it  And,  indeed, the problem with finding teeth of particular species, as Trevor can certainly attest to, is that some of the most diagnostic features can be extremely hard to read from a photograph, if the latter isn't actually misleading... The fact that a lot of sellers, even in Morocco, don't know how to properly identify these teeth definitely doesn't help either. But if you're aware of that you can at least make your own assessments as well

 

Quote

As for "prismatism and facets", is it the angular, polygonal look such as what this tooth explicitly identified as M. hoffmanni has towards the base of its labial surface?

 

There are two leading ways in which mosasaur dental morphology is described: Hornung and Reich (2015) and Street, LeBlanc and Caldwell (2021). I still adhere to the older system, as I believe it's perfect adequate and changing terminologies now would only serve to confuse things again, thereby undoing exactly that beneficial contribution these terminologies aim to achieve through standardization. In any case, the below is an overview diagram (figure 3 from Hornung and Reich, ibid.) that should clarify the terms that I've used. In short, though, "prismatism" would indeed refer to the angular look certain teeth have, whereas facetting refers to flat or concave bands bordered by ridges.

 

 

Quote

In any case many thanks! It should be a fun "hunt" to see if I can identify these species. It seems M. hoffmanni and Tylosaur are some of the rarer ones; are there any more rare species I could look out for?

 

It used to be that P. currii was hard to get - and it still is one of the less common species - but these teeth have been coming onto the market a lot more in certain places recently, so I'd say that, right now, while it's still less common than Globidens phosphaticus or Gavialimimus almaghribensis, it's not as rare as it once was any more. Part of that is that it seems like how common or uncommon certain types of teeth are greatly depends on the submarket you're looking on, if not individual sellers. I have, for example, had people tell me that they had great difficulty getting teeth from G. almaghribensis, whereas I've never had such issues. Then again, the G. phosphaticus and E. heterodontus teeth that were once so abundantly available to me seem to be much rarer now than they ever were, although others assure me they're easily able to get them... Likewise, while clearly identified specimens of the Moroccan tylosaurine and M. hoffmannii are very rare, I've picked them up from online auction sites and even a nearby theme park before... However, one genus that remains rare - even though not as rare as a couple of years ago, when I bought my first few - is Carinodens belgicus and generally anything of this genus (i.e., C. minalmamar) and Xenodens...

[Mochaccino]

16 hours ago, pachy-pleuro-whatnot-odon said:

 

Yeah, you totally nailed it  And,  indeed, the problem with finding teeth of particular species, as Trevor can certainly attest to, is that some of the most diagnostic features can be extremely hard to read from a photograph, if the latter isn't actually misleading... The fact that a lot of sellers, even in Morocco, don't know how to properly identify these teeth definitely doesn't help either. But if you're aware of that you can at least make your own assessments as well

 

 

There are two leading ways in which mosasaur dental morphology is described: Hornung and Reich (2015) and Street, LeBlanc and Caldwell (2021). I still adhere to the older system, as I believe it's perfect adequate and changing terminologies now would only serve to confuse things again, thereby undoing exactly that beneficial contribution these terminologies aim to achieve through standardization. In any case, the below is an overview diagram (figure 3 from Hornung and Reich, ibid.) that should clarify the terms that I've used. In short, though, "prismatism" would indeed refer to the angular look certain teeth have, whereas facetting refers to flat or concave bands bordered by ridges.

 

 

 

It used to be that P. currii was hard to get - and it still is one of the less common species - but these teeth have been coming onto the market a lot more in certain places recently, so I'd say that, right now, while it's still less common than Globidens phosphaticus or Gavialimimus almaghribensis, it's not as rare as it once was any more. Part of that is that it seems like how common or uncommon certain types of teeth are greatly depends on the submarket you're looking on, if not individual sellers. I have, for example, had people tell me that they had great difficulty getting teeth from G. almaghribensis, whereas I've never had such issues. Then again, the G. phosphaticus and E. heterodontus teeth that were once so abundantly available to me seem to be much rarer now than they ever were, although others assure me they're easily able to get them... Likewise, while clearly identified specimens of the Moroccan tylosaurine and M. hoffmannii are very rare, I've picked them up from online auction sites and even a nearby theme park before... However, one genus that remains rare - even though not as rare as a couple of years ago, when I bought my first few - is Carinodens belgicus and generally anything of this genus (i.e., C. minalmamar) and Xenodens...

 

Great to know, that faceting vs prismatism is much more detailed than I was expecting! For me almost certainly difficult to assess just based on photos but one more way to train my eye. I'll see if I can find any Tylosaur and M. hoffmannii just based on our discussions. Carinodens kinda looks like Globidens, and Xenodens seems very distinct from everything else!

 

[Mochaccino]

@pachy-pleuro-whatnot-odon

 

Lemme give this a shot; is this tooth a Tylosaur perhaps? My reasoning is:

 

1. Enamel not as thick as Prognathodon

2. Doesn't seem to be as tall or lingually recurved as in Mosasaurus, though the recurvature is a bit hard to make out just with these photos. At least the tooth seems to lay flat on both lingual and labial sides.

3. Oval-shaped base cross-section rules out Mosasaurus hoffmanni

4. Possible apical curvature? The posterior edge seems quite straight.

 

 

[Praefectus]

2 minutes ago, Mochaccino said:

@pachy-pleuro-whatnot-odon

 

Lemme give this a shot; is this tooth a Tylosaur perhaps? My reasoning is:

 

1. Enamel not as thick as Prognathodon

2. Doesn't seem to be as tall or lingually recurved as in Mosasaurus, though the recurvature is a bit hard to make out just with these photos. At least the tooth seems to lay flat on both lingual and labial sides.

3. Oval-shaped base cross-section rules out Mosasaurus hoffmanni

4. Possible apical curvature? The posterior edge seems quite straight.

No, this is Eremiasaurus heterodontus. Tylosaur is going to have more of a curved hook to the apex. 

 

Sorry for slow replies. School sometimes keeps me away from TFF. 

[Mochaccino]

3 minutes ago, Praefectus said:

No, this is Eremiasaurus heterodontus. Tylosaur is going to have more of a curved hook to the apex. 

 

Sorry for slow replies. School sometimes keeps me away from TFF. 

 

Ah I see, tricky! Welp at least I did some ruling out. So Tylosaur is more curved, Eremiasaurus are more straight? Now that you mention it I do see the curvature of Tylosaur especially along the posterior border:

 

From Hornung & Reich, 2015:

 

From a past listing, though this one is USA:

[Praefectus]

On 3/7/2022 at 5:16 PM, pachy-pleuro-whatnot-odon said:

I'm thinking both teeth could be possible, but the right one in particular. As noted, Eremiasaurus-teeth can be somewhat prismatic in appearance, and the overall outline of both teeth matches what may be expected for E. heterodontus. However, determination of which carinae are present is needed to confirm this. I can see the left tooth being a prognathodontid, but think the tooth on the right is too faceted to match M. hoffmannii. At the same time, the ornamentation of this tooth does remind me of faceting rather than tertiary striae, which would rule out tylosaurine.

I don't know. Maybe? I guess Eremiasaurus could fit. This (2nd pic left tooth) is getting towards the max size for teeth I would assign to Eremiasaurus. The right tooth needs better pictures. 

 

On 3/7/2022 at 5:16 PM, pachy-pleuro-whatnot-odon said:

Yeah, in my opinion, this is kind of where you run into issues with assigning labels to isolated teeth, as P. anceps has indeed been noted to sometimes have "fluted"/faceted teeth (I'll refer to your own extremely useful analysis of the literature), yet there seems to be a lot of mix-up concerning the description of prognathodontid teeth from Morocco that aren't P. currii. To me this means that, unless the teeth were found in clear association (i.e., attached) with identifiable skeletal remains, it remains possible for isolated teeth to have been wrongly identified. The matter needs further analysis. The particular tooth under discussion here (right, 1st batch), though, would, I believe, not be out of place for P. solvayi. having seen the type-specimen myself (and still having a bunch of photographs for reference). Much like other prognathodontids, both this tooth and the teeth of P. solvayi have mesial curvature, while both have a comparable degree of lateral compression, density of facets, and curvature. Likewise, one of the few/only positively identified candidates for an isolated Moroccan P. solvayi has durophagous adaptations, much like regular prognathodontids. Again, the matter deserves further study, but hence my observation that OP's tooth morphologically seems a closer match to P. solvayi than to P. anceps to me...

It's hard identifying things that are not described in the literature 

I tend to think of P. solvayi teeth being having carinae that are directly antero-posteriorly located, especially posterior teeth. I think anterior teeth sometimes have a laterally pointing carina, but most of the jawline has the facing 180° apart. I also don't see much medial curvature in posterior teeth. I guess that given the uncertainty surrounding "P. anceps", an ID of Prognathodon sp. is probably safest. 

[Praefectus]

On 3/8/2022 at 5:53 AM, pachy-pleuro-whatnot-odon said:

Mosasaurus hoffmannii is a tricky one to find, as it's hard to identify, especially just from photographs. Your best bet is to look through teeth that have the Mosasaurus-morphology, such as M. beaugei -i.e., check for mediodistal curvature, unequal cross-section at the base with a flat labial face. Then, if you can barely make out prismatism and facets, that's when you can be pretty certain you've found a M. hoffmannii.

 

Good luck hunting! 

This is a painful process that involves accidentally adding many M. beaugei teeth to your collection. Eventually, you will find a M. hoffmannii, though. 

 

 

[Praefectus]

22 minutes ago, Mochaccino said:

Ah I see, tricky! Welp at least I did some ruling out. So Tylosaur is more curved, Eremiasaurus are more straight? Now that you mention it I do see the curvature of Tylosaur especially along the posterior border:

For the Moroccan tylosaur, it depends on jaw position. Anterior teeth are much more curved that posterior teeth. 

 

Edited March 10, 2022 by Praefectus

[pachy-pleuro-whatnot-odon]

3 hours ago, Mochaccino said:

@pachy-pleuro-whatnot-odon

 

Lemme give this a shot; is this tooth a Tylosaur perhaps? My reasoning is:

 

1. Enamel not as thick as Prognathodon

2. Doesn't seem to be as tall or lingually recurved as in Mosasaurus, though the recurvature is a bit hard to make out just with these photos. At least the tooth seems to lay flat on both lingual and labial sides.

3. Oval-shaped base cross-section rules out Mosasaurus hoffmanni

4. Possible apical curvature? The posterior edge seems quite straight.

 

 

3 hours ago, Praefectus said:

No, this is Eremiasaurus heterodontus. Tylosaur is going to have more of a curved hook to the apex. 

 

Variably, thanks to intraspecific positional differences and interspecific dental similarities, I'd say this tooth could either be described as a juvenile prognathodontid or indeed Eremiasaurus heterodontus. The difference, at least to me, is not a clear-cut one, as there's so much overlap in morphology depending on position in the jaw. Juvenile prognathodontids may exhibit less durophagous enamel around their apex, but do have do have mesial and distal carinae and may, like adult teeth, have a slight backwards curvature. In E. heterodontus anterior teeth typically have only a mesial carina, with durophagous adaptations being less prominent in smaller specimens (especially in teeth from the anterior region of the jaws). I'd say that this is indeed likely E. heterodontus, but certainly not one with the hallmark morphology.

 

2 hours ago, Praefectus said:

I don't know. Maybe? I guess Eremiasaurus could fit. This (2nd pic left tooth) is getting towards the max size for teeth I would assign to Eremiasaurus. The right tooth needs better pictures.

 

Actually, while I agree most teeth belonging to the species are rather small, teeth of Eremiasaurus heterodontus can grow quite large, as these specimens of 2.52" (6.4 cm) and 2.81" (7.1 cm) show (in fact, the darker coloured one was originally marketed as P. giganteus, though morphologically it's clearly a E. heterodontus). These teeth coincidentally illustrate that when teeth from E. heterodontus grow larger, they acquire more durophagous adaptations, though not to the same degree as prognathodontids.

 

 

 

 

3 hours ago, Praefectus said:

It's hard identifying things that are not described in the literature 

I tend to think of P. solvayi teeth being having carinae that are directly antero-posteriorly located, especially posterior teeth. I think anterior teeth sometimes have a laterally pointing carina, but most of the jawline has the facing 180° apart. I also don't see much medial curvature in posterior teeth. I guess that given the uncertainty surrounding "P. anceps", an ID of Prognathodon sp. is probably safest.

 

Yeah, I see I made a mistake when I wrote "mesial curvature", as I meant "along the mesiodistal line", thus, in fact, "distal curvature" (though, in fact, I even meant to refer to the carinae ). All the same "mesial" is not "medial" In other words, we are in agreement that the teeth of P. solvayi would indeed have both mesial and distal carinae and curve distally, much like the teeth of other prognathodontids - which was the point I was trying to make But, you're right, it hard to compare against something that hasn't officially been described from Morocco

 

Notwithstanding, Serge, the guy who created the "Moroccan mosasaurs"-thread believes P. solvayi occurs in the region. And then there's the below tooth, that doesn't match P. giganteus/anceps premaxillary teeth, but which conical shape is a perfect match for P. solvayi (compare with the second image, a premaxilla with teeth from P. anceps [source]; more comparative material on the holotype of P. solvayi in the Museum voor Natuurwetenschappen in Brussels can be found here).

 

 

3 hours ago, Mochaccino said:

Ah I see, tricky! Welp at least I did some ruling out. So Tylosaur is more curved, Eremiasaurus are more straight?

 

3 hours ago, Praefectus said:

For the Moroccan tylosaur, it depends on jaw position. Anterior teeth are much more curved that posterior teeth.

 

There are a lot of features that can help differentiate the two. But, as said, there is unfortunately some overlap and intraspecific variation that complicates things and makes it difficult to come up with a rule that holds true for all cases. As Trevor has pointed out, for example, the anterior-most teeth in any mosasaur species typically have a somewhat different shape from those further down the jaw. I already mentioned that teeth of P. solvayi are much more conical towards the front-part of the jaw, and that the position of carinae in E. heterodontus is also positionally determined. However, anterior/premaxillary teeth are generally somewhat rounder than those further back, whereas the alignment of their carinae also shifts to follow the curvature of the snout.

 

That is: you should imagine an invisible line that runs along the jaw, with the carinae of each tooth having a certain offset to this line. The more you get to the front of the jaw, the more curved this invisible line will become. Yet the relative offsets of both anterior and posterior carinae vis-à-vis this line will remain rather constant. This means that the greater the positional curve in the jaw (the invisible line), the greater the labial surface and the further the carinae are spaced from each other. Since position of the carinae is partially determinative of dental curvature, this also means that the latter also changes as you move along the jawline.

 

Lastly, just by way of illustration, here are some other tylosaurine teeth to compare with (more information can be found here). Note the apical curvature in both specimens, as well as the tertiary striae on the specimen on matrix.

 

 

 

[Mochaccino]

9 hours ago, pachy-pleuro-whatnot-odon said:

 

 

Variably, thanks to intraspecific positional differences and interspecific dental similarities, I'd say this tooth could either be described as a juvenile prognathodontid or indeed Eremiasaurus heterodontus. The difference, at least to me, is not a clear-cut one, as there's so much overlap in morphology depending on position in the jaw. Juvenile prognathodontids may exhibit less durophagous enamel around their apex, but do have do have mesial and distal carinae and may, like adult teeth, have a slight backwards curvature. In E. heterodontus anterior teeth typically have only a mesial carina, with durophagous adaptations being less prominent in smaller specimens (especially in teeth from the anterior region of the jaws). I'd say that this is indeed likely E. heterodontus, but certainly not one with the hallmark morphology.

 

 

Actually, while I agree most teeth belonging to the species are rather small, teeth of Eremiasaurus heterodontus can grow quite large, as these specimens of 2.52" (6.4 cm) and 2.81" (7.1 cm) show (in fact, the darker coloured one was originally marketed as P. giganteus, though morphologically it's clearly a E. heterodontus). These teeth coincidentally illustrate that when teeth from E. heterodontus grow larger, they acquire more durophagous adaptations, though not to the same degree as prognathodontids.

 

 

 

 

 

Yeah, I see I made a mistake when I wrote "mesial curvature", as I meant "along the mesiodistal line", thus, in fact, "distal curvature" (though, in fact, I even meant to refer to the carinae ). All the same "mesial" is not "medial" In other words, we are in agreement that the teeth of P. solvayi would indeed have both mesial and distal carinae and curve distally, much like the teeth of other prognathodontids - which was the point I was trying to make But, you're right, it hard to compare against something that hasn't officially been described from Morocco

 

Notwithstanding, Serge, the guy who created the "Moroccan mosasaurs"-thread believes P. solvayi occurs in the region. And then there's the below tooth, that doesn't match P. giganteus/anceps premaxillary teeth, but which conical shape is a perfect match for P. solvayi (compare with the second image, a premaxilla with teeth from P. anceps [source]; more comparative material on the holotype of P. solvayi in the Museum voor Natuurwetenschappen in Brussels can be found here).

 

 

 

 

There are a lot of features that can help differentiate the two. But, as said, there is unfortunately some overlap and intraspecific variation that complicates things and makes it difficult to come up with a rule that holds true for all cases. As Trevor has pointed out, for example, the anterior-most teeth in any mosasaur species typically have a somewhat different shape from those further down the jaw. I already mentioned that teeth of P. solvayi are much more conical towards the front-part of the jaw, and that the position of carinae in E. heterodontus is also positionally determined. However, anterior/premaxillary teeth are generally somewhat rounder than those further back, whereas the alignment of their carinae also shifts to follow the curvature of the snout.

 

That is: you should imagine an invisible line that runs along the jaw, with the carinae of each tooth having a certain offset to this line. The more you get to the front of the jaw, the more curved this invisible line will become. Yet the relative offsets of both anterior and posterior carinae vis-à-vis this line will remain rather constant. This means that the greater the positional curve in the jaw (the invisible line), the greater the labial surface and the further the carinae are spaced from each other. Since position of the carinae is partially determinative of dental curvature, this also means that the latter also changes as you move along the jawline.

 

Lastly, just by way of illustration, here are some other tylosaurine teeth to compare with (more information can be found here). Note the apical curvature in both specimens, as well as the tertiary striae on the specimen on matrix.

 

 

 

Wow there is a lot that goes into identifying these teeth, and I can see how within-species and even within-individual variation make things even trickier. Those last two photos I think really has the Tylosaur apical curvature pop out to me, very much resembling a hook in its sudden curve. That posterior tooth photo by @Praefectus though is starting to get trickier for me! For now I think I'll stick to looking for teeth with more obvious and distinct characteristics. Thank you both.