Pliosaur & Mosasaur Tooth Collection from Central Texas

[pachy-pleuro-whatnot-odon]

On 7/27/2021 at 3:45 PM, Anomotodon said:

I think this is at least the third time we are disagreeing on ichthyosaur/pliosaur ID, and this time I also think this tooth is ichthyosaurian haha. Yes, there are some mildly anostomosing ridges, but the quadrangular root is definitely more typical of platypterygiines, since this tooth is Cenomanian. 

 

 

You're right in that the root is rather distinct from what would be usual for pliosaurs. Hence, this is also the tooth I'm least certain about in my identification.

 

My impression is still that it's a pliosaur, but that's purely based on ornamentation, as I haven't ever seen ichthyosaur teeth with such fine, sharp and interspersed striations (I think there's plenty more to be said about this in this thread here, which may come to shed some light on this specimen as well). Smooth teeth, yes; teeth with plicidentine enamel folds, yes; teeth with horizontal banding, yes: even polygonal teeth/teeth with prism faces. But never with this type of striae... Let alone where the striations terminate at different distances from the tooth apex.

 

All the same, how do explain the root, then? Honestly, my first impression when I saw the tooth was "mosasaur" due to the nature of the root. But the rest of the tooth's morphology doesn't quite match up with that hypothesis either, the tooth being so conical. Also, the only mosasaur-species known time exhibits vaguely similar striations would be Prognathodon solvayi, which wouldn't have been around at the time yet.

 

My best guess, therefore, would be that the root has simply eroded. If you look at the bottom of the tooth as it lies in the photograph, then it appears that the crown projects past the root in a way that suggests the root here is smaller than it ought to be, especially when you consider how the root does extend beyond the width of the crown on the other side of the specimen (top in the photograph). You wouldn't find this type of connection between crown and root in platypterygiine ichthyosaurs either, which have a neck that expands from the crown, requiring the root proper to be wider than the crown. Between the issues with the striations (what would need to be bulging enamel folds) and this root both appearing narrower than the crown and missing traces of a neck, I'm inclined to stick with my original diagnosis... 

[LSCHNELLE]

On 7/21/2021 at 4:32 PM, LSCHNELLE said:

Sadly  , the (1) tooth apparently got damaged near the root transition area while in transit back from a Fossil Show.  Oh well, here is a more recent shot of it from a different angle glued partly back together. It has always been only one half of the tooth preserved split along its length.  So, I can't get all the different angles because their only were a few available. 

I found some insitu field pictures of the suspect mosasaur tooth.  They are not the best focus, but show original condition

Also, I found at least three more 7 to 11 mm teeth from the Late Turonian South Bosque. The smaller two (together - one loose from matrix) might be Coniasaur based on another area find.  The larger one is similar to the 12 mm one.  I believe that all five Late Turonian teeth mentioned were found in the same shell hash layer. 

[Paleoworld-101]

2) i also thought was more akin to the Platypterygius ichthyosaur teeth that we find here in Australia, rather than a plesiosaurian. 

 

3) is a very nice pliosaur tooth, what's the size? 

[LSCHNELLE]

3 hours ago, Paleoworld-101 said:

2) i also thought was more akin to the Platypterygius ichthyosaur teeth that we find here in Australia, rather than a plesiosaurian. 

 

3) is a very nice pliosaur tooth, what's the size? 

Paleoworld-101, the size is 30 x 18mm for grooved portion plus root mass.  I don't know the root length, because I chose to leave the root in matrix. The tooth was somewhat brittle from exposure to weather and it required reinforcement. 

[pachy-pleuro-whatnot-odon]

2 hours ago, Paleoworld-101 said:

2) i also thought was more akin to the Platypterygius ichthyosaur teeth that we find here in Australia, rather than a plesiosaurian.

 

Now that I'm looking at the tooth again, I'm starting to wonder whether you guys might not be on to something in that it could be a platypterygiine tooth instead. The striae certainly look rounded enough for it (although - and I unfortunately can't find my source back for this, even though I've been looking for quite a while now - I believe striations on pliosaur teeth become less pronounced as the animal grows older). The thing is, though, that those teeth normally have much more pronounced enamel folds that are more or less evenly distributed around the circumference of the tooth, with them terminating at the same height from the tooth apex - as in the image (figure 11 from Fischer, Bardet, Guiomar and Godefroit [2014]) below. Also, the root of the undisputed pliosaur is broken on one side, exposing what appears to be a similar amorphous bone matter similar to what remains of the root of tooth number 2?

 

 

 

 

In any case, it's hard to make these defining features out here (with tooth 2), but it's not inconceivable that they're there. Compare, for example, with the ophthalmosaurid tooth from India, figured below (figure 7 from Prasad et al. [2017]), which enamel folds are also hardly recognizable and seem somewhat dispersed. Although, to be honest, from the supplied photograph it already looks to me that this is not the case, since I see striae terminating before others, see some nearly merging, etc. Still, may be you could provide us with some more photographs of this specific tooth, @LSCHNELLE, from different angles, so that the ornamentation can be better studied? May be this will help resolve the uncertainty.

 

 

 

13 hours ago, LSCHNELLE said:

I found some insitu field pictures of the suspect mosasaur tooth.  They are not the best focus, but show original condition

 

Although indeed a bit blurry, it's still nice to see this tooth in-situ. It remains a very nice specimen

 

13 hours ago, LSCHNELLE said:

Also, I found at least three more 7 to 11 mm teeth from the Late Turonian South Bosque. The smaller two (together - one loose from matrix) might be Coniasaur based on another area find.  The larger one is similar to the 12 mm one.  I believe that all five Late Turonian teeth mentioned were found in the same shell hash layer. 

 

The larger of these looks to me very similar to the first tooth of the original batch, and I would therefore classify it as mosasaur, probably something like Clidastes again. This tooth, to me, also looks too big for something like coniasaur. Which such pieces I presume crocodile would always be an option too, assuming they are known to have occurred in the area. But to me it looks more mosasaur than crocodile for the labiolingual compression the tooth appears to display.

 

The other two teeth, found together, are certainly a good candidate for Coniasaurus. For, while I don't really know too much about this animal, from what I was able to quickly look up, they seem to have been rather diminutive in size, with equally sized teeth (see images below). Their teeth also seem to have been rather robust with almost durophagous adaptations. The only thing that makes me hesitate somewhat is the fact that Coniasaurus-teeth seem to bulge a bit prior to connecting to the root, which exhibits a constriction. It could, however, be that this is species-dependent, or even that these are teeth belonging to a dolichosaurid, which, as I understand (source), is anatomically closely related to Coniasaurus, but which teeth have never been found.

 

 

Coniasaurus sp. jaw and partial, Eagle Ford Formation, Tarrant county, Texas (source)

 

Coniasaurus crassidens (source)

 

Cf. Coniasaurus sp. (figure 1 from Shimada, Everhart and Ewell [2007])

 

 

I believe @LanceH, who's jaws are figured in the first two photographs, is a member of this forum, by the way. So may be he can shed some light on these teeth in particular, but may be also on the other teeth more in general (he's found beautiful pliosaur and platypterygiine ichthyosaur teeth in the past, for instance).

[LSCHNELLE]

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

In any case, it's hard to make these defining features out here (with tooth 2), but it's not inconceivable that they're there. Compare, for example, with the ophthalmosaurid tooth from India, figured below (figure 7 from Prasad et al. [2017]), which enamel folds are also hardly recognizable and seem somewhat dispersed. Although, to be honest, from the supplied photograph it already looks to me that this is not the case, since I see striae terminating before others, see some nearly merging, etc. Still, may be you could provide us with some more photographs of this specific tooth, @LSCHNELLE, from different angles, so that the ornamentation can be better studied? May be this will help resolve the uncertainty.

Here are some more pictures. 

[LSCHNELLE]

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

 

Now that I'm looking at the tooth again, I'm starting to wonder whether you guys might not be on to something in that it could be a platypterygiine tooth instead. The striae certainly look rounded enough for it (although - and I unfortunately can't find my source back for this, even though I've been looking for quite a while now - I believe striations on pliosaur teeth become less pronounced as the animal grows older). The thing is, though, that those teeth normally have much more pronounced enamel folds that are more or less evenly distributed around the circumference of the tooth, with them terminating at the same height from the tooth apex - as in the image (figure 11 from Fischer, Bardet, Guiomar and Godefroit [2014]) below. Also, the root of the undisputed pliosaur is broken on one side, exposing what appears to be a similar amorphous bone matter similar to what remains of the root of tooth number 2?

 

 

 

 

In any case, it's hard to make these defining features out here (with tooth 2), but it's not inconceivable that they're there. Compare, for example, with the ophthalmosaurid tooth from India, figured below (figure 7 from Prasad et al. [2017]), which enamel folds are also hardly recognizable and seem somewhat dispersed. Although, to be honest, from the supplied photograph it already looks to me that this is not the case, since I see striae terminating before others, see some nearly merging, etc. Still, may be you could provide us with some more photographs of this specific tooth, @LSCHNELLE, from different angles, so that the ornamentation can be better studied? May be this will help resolve the uncertainty.

 

 

 

 

Although indeed a bit blurry, it's still nice to see this tooth in-situ. It remains a very nice specimen

 

 

The larger of these looks to me very similar to the first tooth of the original batch, and I would therefore classify it as mosasaur, probably something like Clidastes again. This tooth, to me, also looks too big for something like coniasaur. Which such pieces I presume crocodile would always be an option too, assuming they are known to have occurred in the area. But to me it looks more mosasaur than crocodile for the labiolingual compression the tooth appears to display.

 

The other two teeth, found together, are certainly a good candidate for Coniasaurus. For, while I don't really know too much about this animal, from what I was able to quickly look up, they seem to have been rather diminutive in size, with equally sized teeth (see images below). Their teeth also seem to have been rather robust with almost durophagous adaptations. The only thing that makes me hesitate somewhat is the fact that Coniasaurus-teeth seem to bulge a bit prior to connecting to the root, which exhibits a constriction. It could, however, be that this is species-dependent, or even that these are teeth belonging to a dolichosaurid, which, as I understand (source), is anatomically closely related to Coniasaurus, but which teeth have never been found.

 

 

Coniasaurus sp. jaw and partial, Eagle Ford Formation, Tarrant county, Texas (source)

 

Coniasaurus crassidens (source)

 

Cf. Coniasaurus sp. (figure 1 from Shimada, Everhart and Ewell [2007])

 

 

I believe @LanceH, who's jaws are figured in the first two photographs, is a member of this forum, by the way. So may be he can shed some light on these teeth in particular, but may be also on the other teeth more in general (he's found beautiful pliosaur and platypterygiine ichthyosaur teeth in the past, for instance).

Dr. Polcyn viewed these three teeth (see below repost) and said "Definitely russellosaurian and likely plioplatecarpine but I would not speculate on genus at this point." 

[pachy-pleuro-whatnot-odon]

14 hours ago, LSCHNELLE said:

Here are some more pictures. 

 

Thanks for that!

 

I still find it a bit hard to make out, to be honest, as on the first photograph (the straight on lateral view) the underside/lingual side of the tooth appears devoid of striations. However, on all other photographs, the striae go all the way around the tooth and are equidistantly spaced - which would be an argument in favour of the tooth being ichthyosaurian. Crushing, lighting and the general wear and tear of the tooth make it hard to make out at what point individual striations end, though, and therefore to determine if they all end at the same height from the tooth apex (which would be another ichthyosaurian characteristic). The root throws me off a bit, as it bulges out a bit. But overall I still think I'm sticking to pliosaur. However, see here for a recent discussion I had on the difficulty sometimes of distinguishing between Cretaceous ichthyosaur and pliosaur teeth.

 

May be @Mike from North Queensland has an opinion on this particular specimen?

 

12 hours ago, LSCHNELLE said:

Dr. Polcyn viewed these three teeth (see below repost) and said "Definitely russellosaurian and likely plioplatecarpine but I would not speculate on genus at this point."

 

That's pretty cool, and indeed makes sense for the larger of the teeth. The thought that the tooth could be plioplatecarpine had actually crossed my mind, as it has quite distinct ornamentation. And while I felt that the tooth looked to robust at the time, the doubt wouldn't let me go. Nice to know that my other hunch would've been the correct one on this specimen

 

As to the russelosaurian teeth, that's pretty awesome! I haven't seen teeth from this species before. And even though Russelosaurus is supposed to be a tethysaurine genus, its teeth look completely different from those of Tethysaurus nopscai from Morocco (which to me look way more halisaurine or may be platecarpine in appearance; see image below). I wouldn't have guessed the association, thus it's pretty cool to have seen these. Learned something new today!

 

Tethysaurus nospcai maxillary teeth, Goulmima, Morocco

Edited August 7, 2021 by pachy-pleuro-whatnot-odon