Mosasaurus hoffmanni?

[HunterLacrosse]

I saw this online, labeled as a Hoffmann mosasaur.

 

Species was listed as Mosasaurus hoffmanni

Age was listed as the Upper Cretaceous, Maastrichtian stage, (~66 Million Years)

Location was listed as Oued Zem, Morocco

The formation was listed as Ouled Abdoun Basin (Phosphate beds)

The size listed at 6.7cm

 

Is this true?

 

[Praefectus]

Yes. It is Mosasaurus hoffmannii (spelled with two 'i's). The medial curvature and D-shaped cross-section identify it as Mosasaurus, and the large muted facets on both labial and lingual surfaces match the expected counts for M. hoffmannii. 

[HunterLacrosse]

3 hours ago, Praefectus said:

Yes. It is Mosasaurus hoffmannii (spelled with two 'i's). The medial curvature and D-shaped cross-section identify it as Mosasaurus, and the large muted facets on both labial and lingual surfaces match the expected counts for M. hoffmannii. 

Hi, thanks man

Is this definitely a mosasaurus hoffmannii? I don't know much about fossil teeth, but it looks cool 

[Praefectus]

3 hours ago, HunterLacrosse said:

Hi, thanks man

Is this definitely a mosasaurus hoffmannii? I don't know much about fossil teeth, but it looks cool 

Yes

[pachy-pleuro-whatnot-odon]

3 hours ago, HunterLacrosse said:

Is this definitely a mosasaurus hoffmannii? I don't know much about fossil teeth, but it looks cool 

 

While it's not super-obvious from the provided photographs (for this, photographs of the base and top from angles that show the relative positioning of the carinae would be best), you can still make out from the third photograph that, while the tooth curves back towards the tip, it also turns inward towards what would've been the tongue. This so-called mediodistal curvature is typically of teeth belonging to the genus Mosasaurus. And while you'd expect the labial (lip) side to be somewhat smaller and maybe less rounded than it appears to be in this specimen (hence the D-shaped cross-section mentioned before), there's some variation that occurs dependent on position in the jaw. In any case, the tooth does not appear compressed enough (in addition to having the wrong kind of curvature and other features) to be Hainosaurus boubker.

 

The next clue then becomes the number of prism faces on the labial (convex) and facets on the lingual (concave) side. If these are pronounced and high in number, this would indicate the species being M. beaugei. However, if there are only two to three prism faces, as seems to be the case here (I count three), and prism faces and faceting are muted, the species would be M. hoffmannii, although the distinction can sometimes be a bit tricky to make, as some larger M. beaugei may also have less expressive ornamentation. As with other marine reptiles (e.g., see here for this effect in pliosaurs), this may have to do with the animal's age.

 

As to the name: the holotype specimen of M. hoffmannii was indeed first obtained by the Dutch Dr. Hoffmann, thus you'd correctly expect the species name to be "hoffmanni", from the Latin genitive form of "of Hoffmann" or "Hoffmann's". However, when the species was first named by Mantell in1829 he misspelled the name with a double "i". And while subsequent authors have tried to correct this mistake, and an argument could indeed be made to have the species name changed to use a single "i", the official name currently still stands with a double "i".

[HunterLacrosse]

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

 

While it's not super-obvious from the provided photographs (for this, photographs of the base and top from angles that show the relative positioning of the carinae would be best), you can still make out from the third photograph that, while the tooth curves back towards the tip, it also turns inward towards what would've been the tongue. This so-called mediodistal curvature is typically of teeth belonging to the genus Mosasaurus. And while you'd expect the labial (lip) side to be somewhat smaller and maybe less rounded than it appears to be in this specimen (hence the D-shaped cross-section mentioned before), there's some variation that occurs dependent on position in the jaw. In any case, the tooth does not appear compressed enough (in addition to having the wrong kind of curvature and other features) to be Hainosaurus boubker.

 

The next clue then becomes the number of prism faces on the labial (convex) and facets on the lingual (concave) side. If these are pronounced and high in number, this would indicate the species being M. beaugei. However, if there are only two to three prism faces, as seems to be the case here (I count three), and prism faces and faceting are muted, the species would be M. hoffmannii, although the distinction can sometimes be a bit tricky to make, as some larger M. beaugei may also have less expressive ornamentation. As with other marine reptiles (e.g., see here for this effect in pliosaurs), this may have to do with the animal's age.

 

As to the name: the holotype specimen of M. hoffmannii was indeed first obtained by the Dutch Dr. Hoffmann, thus you'd correctly expect the species name to be "hoffmanni", from the Latin genitive form of "of Hoffmann" or "Hoffmann's". However, when the species was first named by Mantell in1829 he misspelled the name with a double "i". And while subsequent authors have tried to correct this mistake, and an argument could indeed be made to have the species name changed to use a single "i", the official name currently still stands with a double "i".

Thank you very much for your sharing. I feel I have learned a lot. and if i want to take this one, how do I know it's a real fossil and not just a plaster replica? 

[pachy-pleuro-whatnot-odon]

15 minutes ago, HunterLacrosse said:

Thank you very much for your sharing. I feel I have learned a lot. and if i want to take this one, how do I know it's a real fossil and not just a plaster replica? 

 

Tricky question to answer, I think, as it's basically the same question as "what makes a fossil real?" - which becomes especially tricky if the fossil is made out of gypsum itself. For those who've seen a lot of fossils, you know how they are supposed to look and can tell whether something is off or not. In this case, however, I'd say that the shiny stuff on the outside of the tooth - that is, the enamel - is very difficult to replicate by forgers, thus a good indication for the tooth being real. Moreover, with Moroccan fossils, problems typically start when a root's attached to the crown, or the tooth is attached to a jaw. That kind of thing.