New plesiosaur species?

[Per Christian]

Hi all. 

 

I recently acquired a plesiosaur tooth from morocco, khourigba, phosphate deposits. In a facebook group i was told the tooth is thicker than any known teeth from  the area. Have the attentive reader here seen any teeth of this thickness? The tooth is about 2 inches long.

 

 

 

 

 

 

 

[PaleoNoel]

It does look pretty robust compared to most Zarafasaura teeth I've seen come out of the phosphate deposits. It's certainly a possibility that it belongs to a currently undescribed species as new Mosasaur species have been recently named and it doesn't seem like the finds from this formation are slowing down. Lets see what other members think.

@pachy-pleuro-whatnot-odon @LordTrilobite

[Per Christian]

6 hours ago, PaleoNoel said:

It does look pretty robust compared to most Zarafasaura teeth I've seen come out of the phosphate deposits. It's certainly a possibility that it belongs to a currently undescribed species as new Mosasaur species have been recently named and it doesn't seem like the finds from this formation are slowing down. Lets see what other members think.

@pachy-pleuro-whatnot-odon @LordTrilobite

Thanks! I'm looking forward to more replies. Any thoughts as to what I should do with it if it is a new species? I mean to contact the proper museum perhaps

[LordTrilobite]

What do the other angles look like. Hard to tell from just one photo. It does look substantially more robust than the typical Zarafasaura teeth one normally sees. Might still be croc or mosasaur. But need more photos.

[pachy-pleuro-whatnot-odon]

Interesting specimen! From just this one single photograph, I agree that the tooth looks a lot more robust than your typical Zarafasaura oceanis tooth. And although I've seen quite a bit of variation in terms of length, width, curvature, compression and ornamentation amongst teeth described as Zarafasaura oceanis, I haven't seen them this thick and short before. That is, though I've got a couple of teeth that approach yours in terms of girth, they are much longer, and therefore in proportion much more similar to other Z. oceanis teeth I've seen. The tooth's smooth surface ornamentation, however, would seem to indicate this is indeed a plesiosaur tooth, moreover - from what I understand - an elasmosaur tooth. For it to be a crocodile tooth, I'd expect it to have carinae and more pronounced striations. Moreover, since the deposits in this region are Maastrichtian to Eocene, I wouldn't expect any marine crocodiles around, as well as the Cenozoic ones to be much smaller than their late Mesozoic counterparts (i.e., animals that survived the KT-extinction event were generally the smaller ones). Lastly, the root looks much more plesiosaurian than mosasaur.

 

So I'd say that what we have here is indeed a very robust elasmosaur tooth. But that's just an initial estimation. It would still be good to get photographs of different angles to properly compare it to other known specimens. In any case, it's morphologically distinct from the plesiosaurian teeth found around Goulmima - whether they be polycotylid, pliosaur or elasmosaur - yet still is so similar to Zarafasaura oceanis in both preservation and ornamentation, that I would hesitate to classify this as a new species without other comparable specimens or skeletal remains found to confirm this is not a one off/single individual that just happened to have unusually robust teeth.

[Per Christian]

I can only upload one at a time do I'll post a few replies here. It's 5.5 cm in length btw. Really really interesting to read what you guys write. I'm curious to hear more if you are willing to look further at the new pictures

[Per Christian]

And when I used my pretty little head i realized I could change the file size for the pictures.. here comes more. Do let me know if further pictures are desired!

[pachy-pleuro-whatnot-odon]

Nah, I think this will suffice. Stunning tooth, though!

 

These photographs convince me of my earlier determination: definitely a more robust elasmosaur tooth. For me this could still just be Zarafasaura oceanis, even if a notably robust specimen. But I see no inherent reason to declare this a new species...

[Mahnmut]

Hello.

Are there any known trends like "teeth from the back of the jaw are more robust" or "juveniles tend to have shorter teeth" in plesiosaurs or Zarafasaura?

Best regards,

J

[pachy-pleuro-whatnot-odon]

9 minutes ago, Mahnmut said:

Hello.

Are there any known trends like "teeth from the back of the jaw are more robust" or "juveniles tend to have shorter teeth" in plesiosaurs or Zarafasaura?

Best regards,

J

If there are, then I'm not aware of them, as there are only two articles on Zarafasaura oceanis I know off, and I haven't had the opportunity to read either of them:

• Vincent et al., 2011. Zarafasaura oceanis, a new elasmosaurid (Reptilia: Sauropterygia) from the Maastrichtian Phosphates of Morocco and the palaeobiogeography of latest Cretaceous plesiosaurs
• Lomax and Wahl, 2013. A new specimen of the elasmosaurid plesiosaur Zarafasaura oceanis from the Upper Cretaceous (Maastrichtian) of Morocco

It is my understanding, though, that most Z. oceanis cranial and mandibular material is found without teeth in place, thus making it difficult to directly deduce such patterns from the finds themselves. If we look at other plesiosaurian species, however, I think there are some general trends that can be drawn, as there's a distinct patterning in the teeth that can be seen in almost all species. This starts with taller, more slender teeth at the symphysis at the front of the lower jaw, which grow slightly taller before dropping off around the point where the maxilla gives way to the premaxilla. From this greatly reduced size, the teeth pick up in size again, then gradually reduce towards the end of the jaw - the teeth there being both shorted and widest. Overall, the teeth from the upper jaw are larger than those from the lower. Below are a couple of images to illustrate this progression:

 

Pliosaurus kevani, taken from figure 3 of Benson et al., 2013. A Giant Pliosaurid Skull from the Late Jurassic of England

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Muraenosaurus leedsi, taken from figure 4 of Noè, Taylor and Gómez-Pérez, 2017. An integrated approach to understanding the role of the long neck in plesiosaurs

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This same progression is also illustrated in the below pliosaurian teeth from the species (top to bottom) Thalassiodracon hawkinsi, Peloneustes sp., Pliosaurus westburyensis and Pliosaurus carpenteri, with the teeth being arranged that mesial specimens are on the left and distal ones on the right (i.e., from left to right equals front to back):

 

Figure 4 of Sassoon, Foffa and Marek, 2015. Dental ontogeny and replacement in Pliosauridae

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thus, my best guess for OPs tooth would be distal, post maxillary suture, from the mandibula, either from below or just prior to the orbit. This is just a guess, though, as I've got little material to compare against...

[pachy-pleuro-whatnot-odon]

And here's some reconstructed/repaired Zarafasaura oceanis skull material thrown in for good measure