Russian ichthyosaur (Undorosaurus) partial jaw and associated teeth

[bthemoose]

Hi, I'm considering this partial ichthyosaur jaw with 5 teeth (3 in a natural position and 2 others that have been displaced--one is on top and one is on the backside) from Jurassic (Tithonian) deposits in Tartarstan, Russia.

 

The seller, who is also the finder/preparer, has identified this as Undorosaurus and noted that there is repair to the last tooth at the end, which broke and has been glued back together, and some holes that he filled in on that tooth--these are shown in the second photo with the red line (repaired break) and circles (filled in holes), as drawn by seller--but no other restorations or repair.

 

The size of the piece is 6 x 5.5 x 1.8 cm, and the teeth (including root) are 3.5 to 4 cm long.

 

Does this look to be as it's described above, including the genus ID? Any red flags or other things I should know or ask? Thank you!

 

 

[bthemoose]

[pachy-pleuro-whatnot-odon]

Apart from the noted areas, I don't see anything wrong with it, though the quality of the photographs leaves to be desired. Hard to tell whether this is really a jaw, though - partial or otherwise - as the organisation of the bone fragments is hard to make out. But with five teeth so closely laid together - three of which, moreover, are placed in a row - it seems very likely this is a jaw.

 

I can also confirm that the teeth are of an ophthalmosaurid ichthyosaur - they clearly show plicidentine enamel-folds that do not reach the tooth-apex - so Undorosaurus would definitely belong to the options. However, I don't think it's possible to get to the genus-level based on teeth alone. As such, I think genius attribution needs to proceed based on how the teeth hold up to material with certified identification within the same region.

 

Still, nice piece! I certainly wouldn't be sad to add it to my collection!

[bthemoose]

1 hour ago, pachy-pleuro-whatnot-odon said:

Apart from the noted areas, I don't see anything wrong with it, though the quality of the photographs leaves to be desired. Hard to tell whether this is really a jaw, though - partial or otherwise - as the organisation of the bone fragments is hard to make out. But with five teeth so closely laid together - three of which, moreover, are placed in a row - it seems very likely this is a jaw.

 

I can also confirm that the teeth are of an ophthalmosaurid ichthyosaur - they clearly show plicidentine enamel-folds that do not reach the tooth-apex - so Undorosaurus would definitely belong to the options. However, I don't think it's possible to get to the genus-level based on teeth alone. As such, I think genius attribution needs to proceed based on how the teeth hold up to material with certified identification within the same region.

 

Still, nice piece! I certainly wouldn't be sad to add it to my collection!

Thanks for taking a look and providing your thoughts--very helpful!

[RuMert]

Quite possibly the same site as I wrote about here, there aren't many of them in this region. Most likely Kimmeridgian. Nothing has been described from Russian Kimmeridgian due to lack of material, but from Tithonian there are at least 5 genera: Undorosaurus, Nannopterygius, Grendelius, Arthropterygius, Ophthalmosaurus. Assigning is more a matter of personal preference, as it's hard to be sure with teeth alone. Undorosaurus teeth was described as big and robust, Ophthalmosaurus weak and Nannopterygius as thin needle-like with bulbous roots.

[pachy-pleuro-whatnot-odon]

23 minutes ago, RuMert said:

Nothing has been described from Russian Kimmeridgian due to lack of material, but from Tithonian there are at least 5 genera: Undorosaurus, Nannopterygius, Grendelius, Arthropterygius, Ophthalmosaurus. Assigning is more a matter of personal preference, as it's hard to be sure with teeth alone. Undorosaurus teeth was described as big and robust, Ophthalmosaurus weak and Nannopterygius as thin needle-like with bulbous roots.

Yeah, I read that too, about Undorosaurus. However robustness, I think, is a rather relative term that I can even see varying across a jaw or between individuals of the same species. I've seen Platypterygius teeth from Stary Oskol, for example, whose roots were much larger and more robust than the typical tooth from this locality.

 

As Nannopterygius teeth have such a different morphology, and with Ophthalmosaurus teeth being weak to absent, I'd say these teeth must then belong to one of the other three. If we can figure out what teeth they have, we might be able to narrow down on the genus of the jaw section in question.

[paulgdls]

Agree with all the above Well, Brachypterygius are like that too and the genus is predominant in the Kimmeridgian. 

 

[pachy-pleuro-whatnot-odon]

11 minutes ago, paulgdls said:

Agree with all the above Well, Brachypterygius are like that too and the genus is predominant in the Kimmeridgian. 

 

Great photograph! I've been looking for a good picture with some Brachypterygius teeth for some time now. Is there another image database of the Etches Collection, as I didn't find this one amongst the publicly accessible one on their website...

The problem with Brachypterygius as identity for the jaw in question here, though, as that, as it appears, the species hasn't been described from the region. There seems to be some confusion about the proper attribution of Undorosaurus, though. So, with very similar robust teeth, it might well be possible that the genera are synonymous. However, with so little (associated) material having been found of the latter species, it might take a while before such an idea can be properly evaluated.

[paulgdls]

Alexander

 

It's as you say. Still a lot to learn about the Kimmeridgian ichthyosaur lineage. The image was placed on twitter some time back. I'm afraid the images from the online database are low resolution -pity!