[Group B] Crocodile, Alligator, Mosasaur… Tooth ID

[Spr]

Found on Holden Beach, North Carolina. If you need certain measurements let me know, thank you.

[Jared C]

Since none of the east coast folk have seen this yet, I'll give my guesses here. Hopefully it'll bring others more knowledgeable about NC fauna to the thread.

 

As far as I've seen posted online, it seems most of the cretaceous deposits in NC are more inland. Considering this is a beach find, I'd guess they're Miocene or younger. That would rule out mosasaur.

 

I"m actually somewhat confident saying the leftmost tooth is alligator, considering how rotund it is. Not positive on the rightmost tooth, but IMHO its shape suggests alligator as well. We'll see what others have to say

[pachy-pleuro-whatnot-odon]

2 hours ago, Jared C said:

As far as I've seen posted online, it seems most of the cretaceous deposits in NC are more inland. Considering this is a beach find, I'd guess they're Miocene or younger. That would rule out mosasaur.

 

I get the same impression concerning Cretaceous sites in NC - which I believe are generally far and few between. Also, according to this post there might not be any Miocene surface deposits in NC, meaning this material would be younger and thus Pliocene or Pleistocene in age. This seems consistent with preservation, which hints at Pleistocene. Then again, based on the find from the same beach described here, it might well be possible to find Cretaceous age material at Holden Beach. The local geology may even have led to an effective palimpsest, with both Cretaceous and Pleistocene material being found, and both having rather similar modes of preservation. People like @sixgill pete and @fossil_lover_2277 might know more...

 

Quote

I"m actually somewhat confident saying the leftmost tooth is alligator, considering how rotund it is. Not positive on the rightmost tooth, but IMHO its shape suggests alligator as well. We'll see what others have to say

 

These two teeth are indeed alligator teeth. Most teeth don't get as rotund as this. Nice finds! 

Edited April 13, 2022 by pachy-pleuro-whatnot-odon

[sixgill pete]

The material from Holden Beach is being dreged from offshore and is Cretaceous PeeDee Formation.

[Al Dente]

These are both mosasaur. As Sixgill pete already said, these are from the Maastrichtian Peedee Formation. The combination of carinae and oval-shaped indentation of the tooth base are good indicators of being mosasaur teeth.

[pachy-pleuro-whatnot-odon]

1 hour ago, Al Dente said:

These are both mosasaur. As Sixgill pete already said, these are from the Maastrichtian Peedee Formation. The combination of carinae and oval-shaped indentation of the tooth base are good indicators of being mosasaur teeth.

 

I'm quite surprised, to be honest, as the overall shape of these teeth doesn't appear to match mosasaur. Those in the other post (see below), yes - those are clear examples of mosasaur teeth, albeit a bit tricky to identify to genus or species. But these...?

 

 

The first two photographs clearly show the base of the crown of the rightmost tooth folding in towards the root, which is a very uncommon feature in mosasaur teeth, being exclusively restricted to certain durophagous species of the globidensini. And while this particular tooth does exhibit some slightly vermiculating enamel towards the apex in the fifth/last photograph, this is far from enough for a durophagous mosasaur tooth - at least those that I have seen. With the neck of the root in mosasaur teeth more typically fanning out rather than constricting, as is the case here, and the overall shape not being a good match for a globidensine mosasaur, I'd therefore argue that the rightmost tooth is still a crocodilian one, in which these conditions are encountered more often. This is supported by how deep the dental cavity at the base of this tooth is - again a feature seen in crocodilians but not in mosasaurs.

 

Now, of course, this raises an issue with the dating of the material at the site. But here I'd like to quote @hemipristis on the geological make-up of the area, which to me suggests that, while Cretaceous fossils from the Peedee Formation may be the more common vertebrate finds, the fact that the rivers bordering the beach cross-cut Pliocene layers as well does allow for the rare Pliocene fossil to be found as well. And even dismissing this idea, there were certainly also crocodilians with very robust teeth, similar to Deinosuchus, around this area in the Cretaceous, meaning that not all teeth found necessarily default to being mosasaur.

 

2 hours ago, hemipristis said:

Holden Beach is a Pleistocene barrier island with a Pliocene core that is comprised overwhelmingly of quartzose sands mixed with a bit of whatever flows out of the rivers on either end of the island.  The area on the other side of the sound on the mainland is underlain by the Pliocene Waccamaw Formation, a very shelly Pliocene unit, and the stratigraphic equivalent of the famous Yorktown Fm that produces so many beautiful fossils in northern NC and Virginia.  [...]  The two rivers that ultimately discharge into the ocean at the two inlets on either end of Holden Beach meander through both strata.

 

Turning to the leftmost tooth, I think this one is more difficult to identify, and I may indeed have been a bit hasty to dismiss it as alligator. For it doesn't show the constriction of the crown around the neck the other tooth does and has a much shallower dental cavity, which is much more in line with mosasaur tooth morphology. It may therefore well be a prognathodontid mosasaur tooth. However, those as I have seen - with the exceptions of P. currii and I. aegypticus from Morocco - are all much more conical and less rotund than this tooth. This specimen is simply untypically short and stout for a mosasaur tooth, moreover has too little distal curvature for many prognathodontids and does exhibit the features (such as constriction around the base of the crown and anastomosing enamel) associated with durophagous species. Again, something like but not exactly Deinosuchus (which I understand didn't occur in the area for reasons of taxonomic classification rather than morphology) may be a better fit, as these teeth are bulbous, short, round, have vermiculating enamel around the tooth apex and two carinae, little curvature, unconstricted neck of the root, and a generally more alligatoroid morphology.

 

Deinosuchus riograndensis from the Upper Aguja Formation

[Plax]

Both definitely mosasaur, as others have said. Thanks aldente for providing the diagnostic characteristics. There are Pleistocene fossils on the beach a well though as seen by the mastodon and horse teeth found. The dredge sucks up everything with the veneer being modern and Pleistocene and bulk of the sand Rocky Point Member of the Peedee formation.

[Plax]

Quote

Would like to add that the tooth on the left resembles Globidens or Carinodens a bit. Not saying it is just saying there's some resemblance.

 

[pachy-pleuro-whatnot-odon]

9 minutes ago, Plax said:

Would like to add that the tooth on the left resembles Globidens or Carinodens a bit. Not saying it is just saying there's some resemblance.

 

I don't agree. Although Moroccan, I've got a number of examples of both in my collection, and both of these globidensini have constrictions at the base of crown, where it connects with the root. Globidens, moreover, doesn't have any obvious carinae and rather may exhibit a sulcus (depression) at the back of the tooth, whereas Carinodens-teeth are much smaller and highly laterally compressed. Below are a couple of examples to compare against (due to the quality of these images you might need to look a bit more carefully to observe the constriction at the base of the tooth, but it's there):

 

Left maxilla of holotype of Globidens alabamaensis, medial and ventral views (source)

 

 

 

Right dentary of Globidens dakotensis, lateral, dorsal/occlusional and medial views, as well as detail of front-most teeth (source)

 

 

Globidens dakotensis cranium (source)

 

 

Various Carinodens teeth from the Low Countries (figure 2 from Holwerda, Beatty and Schulp, 2013)

[Al Dente]

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

The first two photographs clearly show the base of the crown of the rightmost tooth folding in towards the root, which is a very uncommon feature in mosasaur teeth, being exclusively restricted to certain durophagous species of the globidensini.

 

Here are some examples of mosasaur teeth with the crown enamel curving toward the root. The first set is from a publication and show the posterior teeth with enamel base that curves toward the root. The last two are old photos of a tooth from the Maastrichtian Peedee Formation that I found years ago.

 

 

 

 

[pachy-pleuro-whatnot-odon]

16 hours ago, Al Dente said:

Here are some examples of mosasaur teeth with the crown enamel curving toward the root. The first set is from a publication and show the posterior teeth with enamel base that curves toward the root. The last two are old photos of a tooth from the Maastrichtian Peedee Formation that I found years ago.

 

While I, admittedly, wasn't aware of teeth with such morphology in Eremiasaurus heterodontus - even if it seems to concern only the pre-last, at most last two, teeth, these being aberrant from the rest of the species' dentition, with which I'd otherwise consider myself quite well acquainted - and probably should have made my statement concerning the constriction between crown and root being restricted to globidensini with a little more reservation (if only to take pathological teeth into account), this kind of condition, in my experience, is rare in the plentiful mosasaur teeth and jaws I've seen. This, rather, is my point - that mosasaurs outside of the globidensini typically don't have such a morphology. Of course it'll always be possible to find exceptions, if only in a species that is only known to occur on the other side of the globe. But I'm referring to a more general trend here.

 

As to the tooth you found: what a beauty! The colouration is quite spectacular! The horizontal banding confuses me a bit, though, as that's a character I'd normally associate with crocodilians, where I've observed such a pattern the most, presumably due to the way the enamel of their teeth is constructed. But then the tooth's slight prismatism and distal curvature give it a distinctly mosasaurian look. All the same, the constriction around the crown-root transition is very unusual. Do you know what genus or species it can be attributed to, has it been identified? Now I'm wondering about the rest of the morphology: whether it has zero, one or two carinae, and where; whether it is laterally compressed; how the cross-section looks; what curvature the tooth has...

[Al Dente]

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

The horizontal banding confuses me a bit, though, as that's a character I'd normally associate with crocodilians

 

The banding may be a preservational oddity of North Carolina teeth? Here's a couple of Campanian mosasaur teeth from the NC Fossil Club publication "Fossil Reptiles and Birds". They both show banding. These two are from the NC Museum of Natural Science collection.  

 

The tooth that I found in the Peedee has two carinae that are beaded (close up photo shows the beading). I don't know the genus. 

 

[pachy-pleuro-whatnot-odon]

10 hours ago, Al Dente said:

The banding may be a preservational oddity of North Carolina teeth? Here's a couple of Campanian mosasaur teeth from the NC Fossil Club publication "Fossil Reptiles and Birds". They both show banding. These two are from the NC Museum of Natural Science collection.  

 

The tooth that I found in the Peedee has two carinae that are beaded (close up photo shows the beading). I don't know the genus. 

 

 

Spectacular teeth! Very unusual colouring!  Looks like a Mosasaurus and quite possibly a tylosaurine, making your find a prognathodontid...? Very cool! 

[fossil_lover_2277]

On 4/13/2022 at 4:06 AM, pachy-pleuro-whatnot-odon said:

 

I get the same impression concerning Cretaceous sites in NC - which I believe are generally far and few between. Also, according to this post there might not be any Miocene surface deposits in NC, meaning this material would be younger and thus Pliocene or Pleistocene in age. This seems consistent with preservation, which hints at Pleistocene. Then again, based on the find from the same beach described here, it might well be possible to find Cretaceous age material at Holden Beach. The local geology may even have led to an effective palimpsest, with both Cretaceous and Pleistocene material being found, and both having rather similar modes of preservation. People like @sixgill pete and @fossil_lover_2277 might know more...

 

 

These two teeth are indeed alligator teeth. Most teeth don't get as rotund as this. Nice finds! 

Yea they look similar to other teeth I’ve found in the PeeDee formation. But I’m not about to even try to ID these, y’all can discuss that haha. I’m def not a zoologist/anatomy expert 

[r00t2400]

The one on the left looks pretty spot on to an anterior bottosaurus tooth.