Gently cleaning a tooth from the Moroccan phosphate deposits

[Maniraptora]

Hey all.  I have an Igdamanosaurus agyptiacus tooth from the Late Cretaceous (Maastrichtian Stage) phosphate deposits of Morocco’s Oulad Abdoun Basin. It has one odd little spot with a maroon-covered gunk stuck to it, which I would like to gently clean off of it. The spot is on an area with intact enamel, right next to an area without enamel. First picture shows the spot I’m referring to, second and third are random pictures of this tooth, because why not? Fossil pictures are cool. It’s 1.27 inches wide if that matters, haha.

 

 

[Praefectus]

Nice tooth! The species is Globidens phosphaticus; Igdamanosaurus is not present in Morocco. To remove the phosphatic matrix attached to the crown, slowly drop water onto the sandy grains until it is soft. Use water very sparingly. Only 3-5 drops should do. After that, scrape the matrix away with a sharp metal tool (dental pick, razor blade, knife, ...fork ). The matrix should come off easily enough. 

[Maniraptora]

41 minutes ago, Praefectus said:

Nice tooth! The species is Globidens phosphaticus; Igdamanosaurus is not present in Morocco. To remove the phosphatic matrix attached to the crown, slowly drop water onto the sandy grains until it is soft. Use water very sparingly. Only 3-5 drops should do. After that, scrape the matrix away with a sharp metal tool (dental pick, razor blade, knife, ...fork ). The matrix should come off easily enough. 

Okay, thank you!  I’m mainly bothered by the little maroon-colored sticky spot (seen to the right of the matrix). It looks like it might be organic in origin. Would water work on that, too?

[Praefectus]

Oh, huh. I'm not sure what that is. Is it hard like cement? How attached to the tooth is it? Could you show more pictures? Maybe try scraping it off with a blade. 

[Maniraptora]

3 minutes ago, Praefectus said:

Oh, huh. I'm not sure what that is. Is it hard like cement? How attached to the tooth is it? Could you show more pictures? Maybe try scraping it off with a blade. 

I just did an exploratory scraping with a toothpick, and that almost entirely removed it. It left a little residue, but the spot isn’t visible anymore. It seems like it must be  some type of gooey adhesive. Weird! Thank you again for the advice.

[Praefectus]

Nice! 

[Harry Pristis]

 

 Igdamanosaurus appears to me to be a nomen dubium.  An Internet search shows how little there is to support the designation. Until a neotype is discovered, it appears to be a gross example of taxonomic "splitting."  

Globidens phosphaticus:

 

 

[Maniraptora]

45 minutes ago, Harry Pristis said:

 

 Igdamanosaurus appears to me to be a nomen dubium.  An Internet search shows how little there is to support the designation. Until a neotype is discovered, it appears to be a gross example of taxonomic "splitting."  

Globidens phosphaticus:

 

 

Interesting! The seller I got the tooth from had referred to it as Igdamanosaurus (formerly Globidens), and I wondered what the story behind that was. Are they going on anything more than teeth to justify splitting the genera?

[Harry Pristis]

Classification

  Originally named as Globidens aegyptiacus by Zdansky (1935), the species was first recognised as sufficiently distinct to be separated into its own genus by Lingham-Soliar (1991), who named it Igdamanosaurus after the village of Igdaman (sometimes called In Dama), which was near to where the type specimen was found.

 

  The type specimen, BMNH R11898, is fragmentary and consists of three poorly preserved jaw fragments, two almost complete finely striated teeth, three tooth bases and fragments from at least five broken teeth. Though it is difficult to tell, these remains likely come from the same individual.

  The dentary is noted as being of massive proportions, similar to the massive and robust dentaries found in Globidens and Prognathodon. A medially located shallow recess on the dentary indicates the groove for the splenial.

  Though undoubtedly similar to Globidens in its dental adaptations and similar to G. alabamaensis in possessing unusually small foramina for exits of the mandibular nerve on the lower lateral surface of the dentary, Lingham-Soliar (1991) noted that the vertical striae present in Igdamanosaurus would suggest that it represented a completely new type of durophagous mosasaur that was derived from a Platecarpus-like ancestor rather than a Clidastes-like one and thus classified it as part of the Plioplatecarpinae.

  The latest analyses all place Igdamanosaurus within the Mosasaurinae however, within the Globidensini tribe as a close relative of Carinodens and Globidens.

---Wikiwand

[Maniraptora]

2 hours ago, Harry Pristis said:

Though undoubtedly similar to Globidens in its dental adaptations and similar to G. alabamaensis in possessing unusually small foramina for exits of the mandibular nerve on the lower lateral surface of the dentary, Lingham-Soliar (1991) noted that the vertical striae present in Igdamanosaurus would suggest that it represented a completely new type of durophagous mosasaur that was derived from a Platecarpus-like ancestor rather than a Clidastes-like one and thus classified it as part of the Plioplatecarpinae.

Thanks for the info. Wow, that’s a lot to get out of one feature!  Tyrannosaurus rex specimens definitely vary at least that much.

[Praefectus]

17 hours ago, Harry Pristis said:

 Igdamanosaurus appears to me to be a nomen dubium.  An Internet search shows how little there is to support the designation. Until a neotype is discovered, it appears to be a gross example of taxonomic "splitting."  

 

Igdamanosaurus is valid. It's fossils are reported from Niger and Egypt, though, not Morocco. 

 

From Michaut 2014 and Lingham-Soliar 1991.

 

[pachy-pleuro-whatnot-odon]

However, from Morocco, the below tooth is probably the closest I've ever seen to Igdamanosaurus aegypticus. The lack of further remains, though, probably indicates this tooth may be P. currii.

 

Edited December 16, 2022 by pachy-pleuro-whatnot-odon

[Harry Pristis]

5 hours ago, Praefectus said:

 

Igdamanosaurus is valid. It's fossils are reported from Niger and Egypt, though, not Morocco. 

 

From Michaut 2014 and Lingham-Soliar 1991.

 

I can only repeat, how little there is to support the designation. Until a neotype is discovered, it appears to be a gross example of taxonomic "splitting."  

[Praefectus]

5 hours ago, Harry Pristis said:

I can only repeat, how little there is to support the designation. Until a neotype is discovered, it appears to be a gross example of taxonomic "splitting."

 

How so? Its teeth can be readily differentiated from Globidens in Egypt where both species co-occur (see Bardet 2012). 

 

Igdamanosaurus is notable for having unwaisted, straight, broad, cone teeth that are uniform in shape along the whole jaw and bear enamel folded into "fine parallel ribbing" (Lingham-Soliar 1991). This differs from the highly differentiated dentition in Globidens that varies from short pegs (anterior teeth) to bulbous domes (posterior teeth), which are all waisted and bearing heavy anastomosing enamel. 

 

See J, K, L. Figure from Bardet 2012.

[pachy-pleuro-whatnot-odon]

5 hours ago, Praefectus said:

How so? Its teeth can be readily differentiated from Globidens in Egypt where both species co-occur (see Bardet 2012). 

 

Igdamanosaurus is notable for having unwaisted, straight, broad, cone teeth that are uniform in shape along the whole jaw and bear enamel folded into "fine parallel ribbing" (Lingham-Soliar 1991). This differs from the highly differentiated dentition in Globidens that varies from short pegs (anterior teeth) to bulbous domes (posterior teeth), which are all waisted and bearing heavy anastomosing enamel. 

 

See J, K, L. Figure from Bardet 2012.

 

Interesting figure, as especially specimen L looks a lot like Prognathodon currii. Unfortunately, the lack of standardization in terminology used to describe mosasaur teeth makes it hard to truly understand what Lingham-Soliar meant by "fine parallel ribbing", as in that particular specimen it seems like it may just be anastomosing enamel, whereas from the figure from Michaut (2014) above it would appear Igdamanosaurus aegypticus does actually have some kind of enamel folding going on. Makes you wonder about the potential relationship (or even synonymy) of P. currii and I. aegypticus. For I once created the below overview to help differentiate between the durophageous mosasaurs of Morocco, which led me to the conclusion that there is only minor differentiation between the aforementioned species:

 

As can be seen from this overview, one of the traits distinguishing I. aegypticus from P. currii is the slightly swollen crown base in the latter, which, however, also seems present in the former if going by Michaut (2014) and may actually be absent in P. currii if my specimen above is to be classified as such:

 

16 hours ago, Praefectus said:

 

[Troodon]

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

 

Interesting figure, as especially specimen L looks a lot like Prognathodon currii. Unfortunately, the lack of standardization in terminology used to describe mosasaur teeth makes it hard to truly understand what Lingham-Soliar meant by "fine parallel ribbing", as in that particular specimen it seems like it may just be anastomosing enamel, whereas from the figure from Michaut (2014) above it would appear Igdamanosaurus aegypticus does actually have some kind of enamel folding going on. Makes you wonder about the potential relationship (or even synonymy) of P. currii and I. aegypticus. For I once created the below overview to help differentiate between the durophageous mosasaurs of Morocco, which led me to the conclusion that there is only minor differentiation between the aforementioned species:

 

As can be seen from this overview, one of the traits distinguishing I. aegypticus from P. currii is the slightly swollen crown base in the latter, which, however, also seems present in the former if going by Michaut (2014) and may actually be absent in P. currii if my specimen above is to be classified as such:

 

 

 

I understand Sulci on theropod teeth.  How do you see it on the carinae of mosasaurs teeth?

[pachy-pleuro-whatnot-odon]

1 hour ago, Troodon said:

I understand Sulci on theropod teeth.  How do you see it on the carinae of mosasaurs teeth?

 

The sulci referenced on mosasaur teeth aren't actually located on the carinae. Instead, they just use the generic definition of sulcus as a "furrow" or "groove" to mean a depression in the tooth. That is, when it applies to teeth from the globidensini-tribe. I haven't seen the term applied to the teeth of any other mosasaurs. Below are some examples: double sulci in the rooted specimen, and a single one in the specimen on matrix.

 

[Troodon]

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

 

The sulci referenced on mosasaur teeth aren't actually located on the carinae. Instead, they just use the generic definition of sulcus as a "furrow" or "groove" to mean a depression in the tooth. That is, when it applies to teeth from the globidensini-tribe. I haven't seen the term applied to the teeth of any other mosasaurs. Below are some examples: double sulci in the rooted specimen, and a single one in the specimen on matrix.

 

 

Thank you, always viewed those depressions as some sort of pathology, now I know the correct term.  Do you know if that characteristic is random in a dentition or all the teeth in a particular jaw would have it. 

[pachy-pleuro-whatnot-odon]

8 minutes ago, Troodon said:

Thank you, always viewed those depressions as some sort of pathology, now I know the correct term.  Do you know if that characteristic is random in a dentition or all the teeth in a particular jaw would have it. 

 

According to Bardet et al.'s 2005 description of Globidens phosphaticus, the strongly heterodont dentition can be subdivided into six morphotypes, of which only the posterior-most three - morphotypes D, E and F - bear sulci, these moreover becoming more noticeable the further back in the jaw a tooth comes from (ibid., pp. 170-171). This corresponds to specimens G-H in the below figure 2 from that publication (H representing the back of the jaw, A the front).

 

On 1/3/2021 at 11:05 PM, Calcanay said:

 

The others of aforementioned publication furthermore observe that the markedness of the sulci is something specific to Globidens phosphaticus, as the sulci are way less pronounced, if present at all, in G. alabamaensis and G. dakotensis, which, however, are Campanian species. It would therefore be interesting to compare against the Ozan Formation Globidens, to see if that species has sulci. I've currently got a tooth on the way (but will likely only be able to study and present it halfway through February). But from what I can tell so far, in part based on Lance's north Texas fossil page, no clear sulci appear to be present.

[Praefectus]

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

Interesting figure, as especially specimen L looks a lot like Prognathodon currii.

 

Ugh, that's a fair point. Morphologically, Igdamanosaurus aegyptiacus teeth look like mini-Prognathodon currii teeth. It is probably worth noting that both Bardet and Lingham-Soliar refer to Igdamanosaurus teeth as having "crude anastomosing striations" and "fine parallel ribbing or striae", respectively. Lingham-Soliar went so far as to use the enamel "striations" to suggest moving Igdamanosaurus to Plioplatecarpinae. Differences in terminology aside, it does seem like P. currii has smoother, yet heavier, enamel than Igdamanosaurus. 

 

Like you have on your chart, Bardet 2005 also pointed to height-to-length ratio as a way of differentiating Igdamanosaurus aegyptiacus and Prognathodon currii, noting that while the dimensions were near equal in I. aegyptiacus, the crowns are taller than long in P. currii. 

 

 

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

As can be seen from this overview, one of the traits distinguishing I. aegypticus from P. currii is the slightly swollen crown base in the latter, which, however, also seems present in the former if going by Michaut (2014) and may actually be absent in P. currii if my specimen above is to be classified as such:

 

Your tooth has very strong carinae. Pronounced carinae that pinch off the crown body are seen in P. currii, but absent in I. aegyptiacus. It may be the case that the carinae are abraded away in all Igdamanosaurus specimens, though. 

 

 

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

The sulci referenced on mosasaur teeth aren't actually located on the carinae. Instead, they just use the generic definition of sulcus as a "furrow" or "groove" to mean a depression in the tooth. That is, when it applies to teeth from the globidensini-tribe. I haven't seen the term applied to the teeth of any other mosasaurs. Below are some examples: double sulci in the rooted specimen, and a single one in the specimen on matrix.

 

18 minutes ago, Troodon said:

Thank you, always viewed those depressions as some sort of pathology, now I know the correct term.  Do you know if that characteristic is random in a dentition or all the teeth in a particular jaw would have it. 

 

That was my understanding of the term too. You know, in Street, LeBlanc, and Caldwell 2021's attempt to redefine mosasaur tooth terminology, they never bothered to define "sulcus". Never mind the fact that "absent sulci in Globidens simplex" is one of the few differentiating characters they use to establish it as a new species in LeBlanc, Mohr, and Caldwell 2019 (where it is also not defined ). 

 

It seems to be jaw-position related. Mid-to-posterior teeth have them while anterior teeth do not. Sulci are supposedly a species-specific diagnostic character.

[Maniraptora]

I just "learned something new" a bunch of times over in all these comments, haha. I too would have assumed those mosasaur sulci were pathological. Teeth are complicated!