Platecarpus ptychodon?! Central Texas

[Cambjm06]

Found this today in a dry creek bed where I have found previous cretaceous pieces (sharks teeth). Was just laying there in some small gravel.  Roughly 3 CM and some (small) change. 

Edited July 21, 2022 by Cambjm06

[IsaacTheFossilMan]

@pachy-pleuro-whatnot-odon @Praefectus

[Fossildude19]

Cool looking tooth!

Thanks for posting it.   

[pachy-pleuro-whatnot-odon]

Platecarpus ptychodon is an old and invalid name that was used to refer to what is now known as Gavialimimus almaghribensis, a genus and species that is only known from Morocco. This tooth is not that - though I do agree it look reptile. It's hard to tell whether the specimen has any ornamentation (e.g., striations), though, or whether what I'm seeing is rather cracking in the enamel. It's also hard to tell whether or not the piece has sharp cutting edges on the front and back sides of the tooth. Its overall conical shape is rather generic, which means the specimen cannot easily be assigned to one or the other clade. Thus, it would also help to know a bit more about the geological context in which this was found. You say this tooth was found amongst Cretaceous finds, but do you know from what part of the Cretaceous? If not, we've got many knowledgable members that might be able to figure this out based on approximate locality information. Knowing what other fossils have been found in the area would be another way to determine age.

 

Currently, I'm thinking this tooth does indeed most look like a mosasaur, with carinae front and back. The tooth also appears to bear raised ridges, however, for which reason, based on the information presently available I wouldn't yet want to rule out plesiosaur (sensu lato). Answers to the above questions and more crisp photographs, especially some at off angles, would help narrow down the possibilities of what this could be.

 

Whatever the case: nice find!

Edited July 21, 2022 by pachy-pleuro-whatnot-odon

[Cambjm06]

Hey there @pachy-pleuro-whatnot-odon! Thanks so much for the knowledge! It was found in eastern Travis County, Texas. I do not know a ton about the geology, but would love to learn more. I am adding some photos of my other finds from the same 2 miles of water. If any other specific photo angles would be helpful, just let me know and I can try and capture them. It's an odd color to get my cell phone camera to focus on. 

[pachy-pleuro-whatnot-odon]

@Jared C @Ptychodus04 @JohnJ Would any of you, based on associated finds and locality information, know what age the tooth might be? I'm unfortunately not quite familiar with the geology of Travis County, although I believe the Austin Chalk crops up there, which would make the tooth Santonian-Campanian in age, ruling out not just ichthyosaurs, but also pliosaurs and elasmosaurs (the latter based on morphology), and make mosasaur the more likely. This is confirmed by the two carinae I think I'm seeing. As the tooth is otherwise rather upright and conical, without any lingual curvature (towards the tongue) and there appear to be tertiary striae along the base of the crown, I'd say this is likely to be a Tylosaurus sp..

 

(source)

[Jared C]

Awesome find! Considering the general area you provided, and seeing the "look" of those fossils, I'm fairly sure I've hit the same creek before (keep it secret!). Creeks in that area cut through a smorgasbord of formations, but for the most part, finds come from the Austin chalk and the Ozan. All of the three mosasaur teeth I've seen from your area were fairly posiitively ID'd as Tylosaurus proriger, but I know Platecarpus is another main player. It seems a bit robust for a Platecarpus, but I don't see much of the curvature in the upper third of the tooth that I'm used to from T. proriger. I would default to @pachy-pleuro-whatnot-odon's ID of T. proriger.

 

Now, you may not realize it, but by far your rarest find in that batch is the chunk of cidarid echinoid. It's the left most echinoid (the one to the right is likely some phymosomatid).

If you don't mind, can you share some bright, close, clear photos of the cidarid piece? 

[Cambjm06]

17 minutes ago, Jared C said:

Awesome find! Considering the general area you provided, and seeing the "look" of those fossils, I'm fairly sure I've hit the same creek before (keep it secret!). Creeks in that area cut through a smorgasbord of formations, but for the most part, finds come from the Austin chalk and the Ozan. All of the three mosasaur teeth I've seen from your area were fairly posiitively ID'd as Tylosaurus proriger, but I know Platecarpus is another main player. It seems a bit robust for a Platecarpus, but I don't see much of the curvature in the upper third of the tooth that I'm used to from T. proriger. I would default to @pachy-pleuro-whatnot-odon's ID of T. proriger.

 

Now, you may not realize it, but by far your rarest find in that batch is the chunk of cidarid echinoid. It's the left most echinoid (the one to the right is likely some phymosomatid).

If you don't mind, can you share some bright, close, clear photos of the cidarid piece? 

@Jared C Wow, thanks for giving me all that added context I'm so excited to learn more about it! T.proriger was huge!  It does not have much curvature to it at all, but does seem to have the lines or carinae that pachy mentioned (learning so many new words here lol). I would never mention this body of water's holy name on the internet, but I love it there, never know what your eye will spy. Here are the photos you requested, if you need anything else angle wise, let me know. The conch shell threw me for a loop last week, though not that old (I dont think). 

Edited July 21, 2022 by Cambjm06

[Cambjm06]

Sorry, @Jared C I now realize you meant this one: 

[Jared C]

2 minutes ago, Cambjm06 said:

Sorry, @Jared C I now realize you meant this one: 

Awesome. I was curious if enough detail existed to make a comparison to two other specimens that I know of. Your Cidarid, by the way, almost certainly comes from Austin Chalk (upper cretaceous), based on the other fossils you found it in it's vicinity and what I know about the geology around there.  

 

Cidarids are rare everywhere, but are more usually found in lower cretaceous strata. Upper Cretaceous Cidarids are a tier rarer. Your specimen seems a bit water rolled to draw a close comparison but it's cool that you found it regardless! Compare with an Austin Chalk specimen below:

 

Another reason cidarids are cool is because they still exist, in many extremely bizarre forms, as the most primitive sea urchins alive today

 

[Cambjm06]

Very cool, I can see especially in the second example pic how the circles/line pattern matches up with mine. I will move that one from the outside fossils to the inside shelf lol. Thank you again for all your shared info! 

[Coco]

Hi,

 

25 minutes ago, Jared C said:

 

 

 

Oh, my avatar on the right side bottom !

 

Coco

[Praefectus]

 

I would also call this a mosasaur tooth, likely Tylosaurus. 

[JohnJ]

For comparison, maxillary teeth from a Tylosaurus sp. found in the Austin Chalk.

 

Premaxilla

 

 

Maxilla

 

Maxillary teeth

 

 

[pachy-pleuro-whatnot-odon]

11 minutes ago, JohnJ said:

For comparison, maxillary teeth from a Tylosaurus sp. found in the Austin Chalk.

 

That's an awesome specimen!  And these enamel folds on the maxillary teeth are really unusual too - don't see them that often in mosasaurs in general (except for P. solvayi) - but this is also the first time I see them on a tylosaurine. Most of the material I've seen - whether Moroccan, US, or "Hainosaurus" bernardi from the Low Countries - has much more subtitles tertiary striae around the circumference of the base of the tooth (if anything at all) - although T. ivoniensis from the Kristianstad Basin in Sweden, shown below, also has elongate enamel folds, albeit of a narrower variety (source):

 

[ThePhysicist]

I'm just here to appreciate the Cretoxyrhina 

[Ptychodus04]

Isolated teeth can be hard to positively ID. While I agree with the others that it looks tylosaurine, for accuracy’s sake I would label it as “Mosasaur indet. cf. Tylosaurus sp.”

 

Without a mosasaur expert looking at it, this is the most specific identification that you can use, especially since it was found in float rather than in situ, as @Jared C noted that the specific creek passes through multiple formations.