Jump to content

Pliosaur teeth? or Polycotylid teeth?


talon22

Recommended Posts

This is a continuation of the previous threads about the Plesiosaur jaw (Found near Goulmima, Morocco) that was for sale....

 

So i was thinking about the teeth that came with the jaw i bought, i asked a plesiosaur expert and he believes that the teeth look like they are from a Pliosaur as they don't seem to match Zarafasaura or Thililua. The teeth however, are quite slender (the bigger one is 1.5 inches and the smaller is around 1 inch), so i wanted to ask about any diagnostic features on either of the teeth that can help describe it to family level - especially since the teeth were associated with the jaw and if i can narrow down the teeth, then the jaw can be narrowed down too. Any ideas? 20180621_160615.thumb.jpg.b18f6f01a5c16efd66c03989b228f579.jpg

 

 

 

 

  • I found this Informative 1
Link to comment
Share on other sites

Cannot help you with your question but can add that Manemergus anguirostris is another Plesiosaur described from the Goulmima assemblage.  A quick search shows the holotype skull is without teeth.  All I can add to your search.

  • I found this Informative 2
Link to comment
Share on other sites

Wow, you won that jaw with the teeth? Awesome! I'm glad to see it went to a TFF member. :D 

 

This is a weird one, because you have teeth that resemble those of a pliosaur and a jaw that resembles an Elasmosaur. The only thing I can tell you is the jaw is very similar to that of Libonectes, and it's not the right shape to match Manemergus, or any polycotylid for that matter. If I were you I would show the jaw to the plesiosaur expert to see what he says about that. 

  • I found this Informative 1
Link to comment
Share on other sites

Thanks, Yeah Manemergus was the id given to the jaw + teeth. However i can't seem to find any pictures of polycotylid teeth so hard to determine if the jaw could be Manemergus or Thililua. The only Pliosaur i believe described from the Goulmima assemblage is Brauchauchenius (which iirc was also found in North America)..... there is also the Elasmosaur Libonectes which is a possibility.

 

I suppose there is also the possibility of it belonging to a new undescribed species.

 

https://www.researchgate.net/publication/281165280_A_new_record_of_the_pliosaur_Brachauchenius_lucasi_Williston_1903_Reptilia_Sauropterygia_of_Turonian_Late_Cretaceous_age_Morocco

 

 

Here are some pictures of the jaw

 

20180621_160413.thumb.jpg.475c4d47d5ff2acb3c2294b3437f80b9.jpg20180621_160433.thumb.jpg.0c6e2fd266783b6093c539ee3613f8b7.jpg20180621_160443.thumb.jpg.6e820b46722cd6db062e2fe635bd432e.jpg

 

 

  • I found this Informative 1
Link to comment
Share on other sites

@LordTrilobite might have something to add?

  • I found this Informative 1

“...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin

Happy hunting,

Mason

Link to comment
Share on other sites

Maybe it's not an Elasmosaur nor Pliosaur, but something in-between? A Pliosmasaur :P 

  • I found this Informative 1
Link to comment
Share on other sites

24 minutes ago, Bone guy said:

Maybe it's not an Elasmosaur nor Pliosaur, but something in-between? A Pliosmasaur :P 

Hahaha......you might be on to something :)

  • I found this Informative 1
Link to comment
Share on other sites

And this is a picture of the jaw of Brachauchenius Lucasi (the Pliosaur) described from Morocco. I actually think the jaw i have matches quite well with this, although i may be mistaken, for the moment i lean to the jaw + teeth belonging to a Pliosaur.

 

(Colour online) (a) Photograph, with the localization and detail of the three teeth (1â3); (b) 3D reconstruction; and (c) interpretative drawing of Brachauchenius lucasi specimen MNHN GOU 11 in dorsal view, with the numeration of the different elements measured. 

  • I found this Informative 4
Link to comment
Share on other sites

I can agree with the pliosaur idea. You also have to consider how close together the teeth are in your jaw, and it matches well with the pliosaur.

Link to comment
Share on other sites

I asked a Plesiosaur expert about the jaw and teeth and he was kind enough to respond to my email, here is the response i received

 

Hi Michael

The tooth sockets are large, but not unusually so for a plesiosaur. 

image.png.dc4c6006a35e62ac0360a6d1692e1a06.png

This is a section of the lower jaw of Pliosaurus kevani (with my feet beside it to give some idea of the scale of the animal!). 
What I find more interesting in your jaw is that the alveoli for the replacement teeth are some way down on the lingual side of the ramus, which is unusual in a plesiosaur. P.kevani is fairly typical for the their position. It certainly doesn't look like Manemergus. The teeth and jaw are too robust.
I can't really comment Brachauchenius. I can't find any figures of the lower jaw and have not had the opportunity to examine any specimens. My feeling - which has to be taken very lightly as I have not seen and handled your specimen - is that it is a pliosaur of some sort, and most likely not one which has been described in the scientific literature.


 

  • I found this Informative 3
Link to comment
Share on other sites

The larger tooth certainly seems quite pliosaurine imo, seeing how it's quite robust for a plesiosaur tooth. It looks awfully similar to some Brachauchenius lucasi teeth from Kansas (Since they're also found in Morocco, I guess that works), especially the one below.

Image result for brachauchenius tooth                 Image result for brachauchenius tooth

 

Doing some research, it turns out that Brachauchenius lucasi is the only true pliosaur described in Morocco (the others are polycotylids). Here's a map of every cretaceous pliosaur/polycotylid described so far according to Angst & Bardet (2015)

5b306c84bdff6_mapofcretaceouspliosaurs.PNG.06532908ad4b61c995425c2926f9d1cc.PNG

 

Here's a comparison between your jaw and MNHN GOU 11 (The Moroccan jaw). I scaled the sizes to be proportional based on tooth hole counts (16 tooth holes) The odd thing is that your jaw seems to show a slight bulge by the snout, which the Brachauchenius lucasi jaw clearly lacks. The bulge resembles most like that of from Simolestes vorax

image.thumb.png.42f886eef57e35214d18871c957f3d5e.png

 

And here's the jaw in question compared to a Manemergus anguirostris mandible. Notice how the there is an extra tooth socket in the jaw in question, and how the posterior sockets clearly are similar in diameter with the laterals, opposed to the Manemergus posterior teeth being much smaller than the laterals. Also the latter's tooth sockets are more spread out rather than compact. Infact, it seems that every polycotylid has tooth sockets that are spaced out. The Thililua jaws you posted above clearly has some spacing between each socket.

image.png.31abc24ff660d987f8d1c65e073b5f4f.png

 

Here is a comparison of some of the pliosaur mandibles. The Goulmima specimen is MNHN GOU 11.

image.thumb.png.5c44a0764adfbb1de7536661d479983d.png

 

The seller told me that you can actually attach the teeth into the sockets, although I'm not sure how. Is it possible for you to try that and send a picture of the with the teeth in situ the jaw?
I guess that it is most likely that the jaw is that of a true pliosaur, but one that may be undescribed or some weird variation of Brachauchenius. 

  • I found this Informative 7

If you're a fossil nut from Palos Verdes, San Pedro, Redondo Beach, or Torrance, feel free to shoot me a PM!

 

 

Mosasaurus_hoffmannii_skull_schematic.png

Link to comment
Share on other sites

On 6/25/2018 at 3:12 PM, Macrophyseter said:

The seller told me that you can actually attach the teeth into the sockets, although I'm not sure how. Is it possible for you to try that and send a picture of the with the teeth in situ the jaw?

It is very difficult due to the matrix around the teeth, and i don't want to try to remove it as i believe i may damage them. However i took some pictures of the teeth on top of the tooth sockets where i believe they originally were (due to the two marks in the sockets).

 

20180626_153739.thumb.jpg.72f87ce18360d4962e0ca74aaae2de4c.jpg

20180626_153701.thumb.jpg.125f3347eb02d6bf48b31c1dd7fc5ee4.jpg

20180626_153517.thumb.jpg.089ad0c70b3ff7988b120f32e41f5a01.jpg

Link to comment
Share on other sites

  • 1 year later...

I realise that this thread by now is rather old, but I feel that the matter hasn't ever really been resolved and therefore just wanted to add my 2cts to the discussion.

 

First off, one thing I think we need to let go of is the implicit assumption that the teeth and jaw belong together. We've already heard various arguments on that this may not be the case; there is no supporting evidence that the teeth were associated with the jaw, unless the seller explicitly stated so - and even then there's no evidence that they came out of the jaw, even if the seller suggests you can stick them in there; the one tooth seems too big for the jaw; and the other has matrix surrounding it, suggesting that it never was part of the jaw even if associated. If the teeth were indeed associated with the jaw, they could have ended up in the same place as the jaw due to pre- or post-depositional processes. Such as: a) a pliosaur (or polycotylid) feeding on the jaw; or b ) the teeth just having been redeposited (rolled up next to) the jaw section in much the same way that in Lyme Regis you'll often find small ammonites piled up next to pieces of fossiled wood, having been pushed there by water currents, and blocked from further transposition by the wood's influence on the water flow. This frees us up to think more independently about the identification of the jaw and teeth and even allows us to consider the teeth individually. For as @Bone guy said:

 

On 6/22/2018 at 4:47 AM, Bone guy said:

This is a weird one, because you have teeth that resemble those of a pliosaur and a jaw that resembles an Elasmosaur. The only thing I can tell you is the jaw is very similar to that of Libonectes, and it's not the right shape to match Manemergus, or any polycotylid for that matter. If I were you I would show the jaw to the plesiosaur expert to see what he says about that. 

 

As to the identity of the teeth, I think this will remain difficult, seeing as that they're just too covered in matrix and worn to really make out their diagnostic features. To me, the presence of a carina on the one tooth would suggest Polycotylidae indet. (that is, T. longicollis or M. anguirostris), but I haven't come across any images for comparison yet. There are some similarities with the below tooth, though (especially the smooth-looking surface), which has been described as pliosaur. But then again, I find that even suspected polycotylid-material from Goulmima is frequently identified as such, so this might not actually be saying a lot.

 

 

The second tooth, with the striations on it, I'd also likely classify as polycotylid, seeing as B. lucasi is still the only currently described pliosaur from Goulmima/Morocco, and it's teeth, both American and otherwise, have many more striations all around the tooth, moreover reaching towards the apex. For reference, compare the images below. This, by the way, is not the say that the two teeth are from the same polycotylid species. For that I'm don't know enough of hetrodonty amongst polycotylids, though from what I've seen in pliosaurs (reconstructions) in museums, there seems to be some degree of hetrodonty.

 

On 6/25/2018 at 7:12 AM, Macrophyseter said:

Image result for brachauchenius tooth                 Image result for brachauchenius tooth

 

image.png.52320145bc793e48c32fdb337b72d5d4.png (from Angst & Barget, 2015. A new record of the pliosaur Brachauchenius lucasi Williston, 1903 (Reptilia: Sauropterygia) of Turonian (Late Cretaceous) age, Morocco , figure 2)

 

 

 

 

 

 

 

 

As to the jaw, this is a completely different story. For one of the arguments I've been missing in that discussion concerns the symphysis. That is, one of the most telling signs to tell pliosaurs, polycotylids and elasmosaurs apart is, IMO, the symphysis. In elasmosaurs these are very short and shallow, present only at the very distal-most end of the mandible, where the two parts making up the mandible join. That is, an elasmosaur jaw looks almost like a single bone element, with only a small dividing line (the symphysis) visible on the midline. Take the below Libonectes morgani mandible as an example (taken from here).

 

Libonectes morgani mandible

 

Both other groups of plesiosaurs have more marked symphyses. See below (again Angst & Bardet, 2015):

On 6/25/2018 at 7:12 AM, Macrophyseter said:

 

image.thumb.png.5c44a0764adfbb1de7536661d479983d.png

 

The main differences between pliosaur and polycotylid symphyses are the length and robustness, with those of pliosaurs being more robust and shorter than those of polycotylids, frequently forming a bulge in the mandible. The symphyses of polycotylids are much more gracily, with the conjoined part of the jaw being much longer.

 

The symphyses of pliosaurs and polycotylids are easily recognizable because, on the one hand, this is simply where the two dentaries join, but, on the other, is also marked by a thickened midline that runs to the end of the jaw. See below examples.

 

image.png.2ebf4082102d711273ddeacabb652772.png (from Noè, Smith and Walton, 2004. A new species of Kimmeridgian pliosaur (Reptilia; Sauropterygia) and its bearing on the nomenclature of Liopleurodon macromerus)

 

 

 

 

 

 

 

 

image.thumb.png.eb42467e0ae4bcbaa18c77db5c5fd23a.png(from Sassoon, Noè and Benton, 2012. Cranial anatomy, taxonomic implications and palaeopathology of an Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Westbury, Wiltshire, UK, figure 9) 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Now, obviously such a symphasis is not present on the jaw currently under review, but we can still make inferrences based on its absence. For one, if this were to be a polycotylid jaw, the fragment would have to go very much towards the end of the dentary, proximal to the rest of the body, as the inside of the jaw doesn't show any signs of having been conjoined with the other dentary (best seen in the first image of the original post referenced below).

 

 

Moreover, the mandible seems too tall for either of the polycotylids known from Goulmima. See below for Thililua longicollis (left & top right) and Manemergus anguirostris (bottom right). I've personally seen the second and third specimens, and the jaws are indeed very narrow and shallow (second specimen kept on display in the Sauriermuseum Aathal, third in the Staatliches Museum für Naturkunde Karlsruhe).

 

1-s2.0-S1631068303000630-fx3.jpg (from Bardet, Pereda Suberbiola and Jalil, 2003. A new polycotylid plesiosaur from the Late Cretaceous (Turonian) of Morocco, figure 3)

 

5ede0e8294361_Thililualongicollis.thumb.jpg.5bdef5257d74a5ba309af416541fb68d.jpg

 

Manemergus_anguirostris_skull.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pliosaur does also not sound likely, since the jaw, to me, seems to gracile for the part leading up to the symphasis (even when allowing for the smaller jaw size compared to a full-grown specimen). Moreover, to re-quote the pliosaur expert quoted above:

 

On 6/22/2018 at 4:25 PM, talon22 said:

What I find more interesting in your jaw is that the alveoli for the replacement teeth are some way down on the lingual side of the ramus, which is unusual in a plesiosaur. P.kevani is fairly typical for the their position

 

If we take this together with the lack of horizontal curvature in the jaw, but presence of a veritcal twist (seen below), I believe the reason why the alveoli for the replacemenet teeth are in such a strange position is because the jaw as a whole is tilted.

 

On 6/25/2018 at 7:12 AM, Macrophyseter said:

image.png.31abc24ff660d987f8d1c65e073b5f4f.png

I believe the jaw should not be held upright, as it is shown in most photographs on this topic, but rather with a slight overhang, so that the tooth-sockets point outwards. What you'd end up with would more approach the type of jaw seen in the images from the post below, which is a Libonectes atlasense.

Plesiosaur-1.jpg.fa1fd5163aa267e9fd8fe1078945a65e.jpg

 

I know this is the proposition @Bone guy made a long time ago, but the above is my argument for why I agree with him. His image of the Libonectes atlasense skull was taken from Sven Sachs post here, by the way, for those interested in reading up on that.

 

Edited by pachy-pleuro-whatnot-odon
Formatting
  • I found this Informative 2

'There's nothing like millions of years of really frustrating trial and error to give a species moral fibre and, in some cases, backbone' -- Terry Pratchett

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...