Search the Community

Hi all, First off, this is not my fossil (though I own a large crow of similar morphology), but one I recently bumped into and found particularly curious. Why? Because it's morphology seems to contradict itself. Described as a Polyptychodon interuptus (no longer considered a valid genus; Madzia [2016]) from the Late Jurassic Volga Beds (?) of Stary Oskol, the tooth appears to have enamel folds consistent with what one might expect from an ophthalmosaurid ichthyosaur, such as Platypterygius sp.. The root, however, is smooth and round, with a hollow base, which, unlike the rectangular and "fibrous" roots more typical of ophthalmosaurid ichthyosaurs, is more indicative of pliosaur. Here are some pictures of the tooth. Unfortunately, as it was sold off by auction back in 2017, there's no chance of getting any better quality photographs: I know the seller is quite familiar with pliosaur teeth, so would be surprised if they identified the tooth wrongly. The ornamentation on the tooth, however, bugs me as not matching what I would expect for pliosaur, especially a brachauchenine species. Below are a schematics illustrating various tooth crown ornamentations amongst marine reptiles (figure 2 from McCurry et al. [2019]) and some examples of British brachauchenine pliosaur teeth (figures 3, 4, 5 and 6 from Madzia [2016]) for comparison. Tooth ornamentation in marine reptiles: A. Deinosuchus rugosus; B. Spinosaurus; C. Ichthyosaurus; D. Pliosauridae indet.; E. Globidens alabamensis; F. Hydrurga leptonyx; G. Mammalodontidae indet. Here's the only confirmed Stary Oskol pliosaur tooth I've been able to find as a reference for how the above translates to that location (source): And, finally, for completeness, some Stary Oskol platypterygiine ichthyosaur teeth: My questions to you are: Does this look like an ichthyosaur or pliosaur tooth to you, and why? I've heard, by word of mouth (i.e., got from a source that's not academic), that certain late ophthalmosaurid species developed root tooth roots. Can anybody confirm or deny this, if possible with academic reference? Thanks for your help! @RuMert @Anomotodon @paulgdls @PointyKnight @Mike from North Queensland @-Andy-

Went out for a hunt with friends today on a local creek in Denton County, Texas and came across this great tooth. Better beat up that not to find at all. Was totally stoked when I saw the tip and thought I had found a large mosy in this creek. Was even more excited when I made out what I had really found.

So I've gotten myself into an extremely rare deal- a mosasaur and pliosaur tooth both in the US for a great price. The goodies arrived today, and I might as well show em off. First off, we have a mosasaur tooth from the Ozan Formation of Fannin County. Knowing that the NSR flows inside Fannin County and is also part of the Ozan Formation, This tooth is probably also from the NSR itself. Although the seller didn't have time to do a full ID on the tooth and simply labeled it as unidentified, by extensive comparing with other mosasaur teeth from the area, I can promptly assume that this is cf. Tylosaurus proriger, meaning that after 11+ years of my life, I finally have a T. proriger tooth . Next, we got a tooth that has been sought out for by countless collectors- a north american pliosaur tooth. As with other Texan pliosaur teeth, this one was from the Britton Formation near Dallas. Again, the seller labeled it as an unidentified pliosaur. This time though, IDing is difficult. Based on my knowledge, the two possible candidates are Brachauchenius lucasi and Polyptychodon hudsoni, which both have been found in this area. But as its hard to tell the difference between the two in teeth, I can't make a solid pinpoint. Maybe I'll just be biased and label it as cf. Brachauchenius lucasi because brachs are more iconic to me and due to the unstableness of the polyptychodon taxon. Although not as large as other's tylosaurus teeth, this one still kicks over 4 cm which is still pretty big to me. The pliosaur tooth is just over 2 cm, making it quite small but worth due to its rarity.