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A tooth I recently pulled from my Woodbine honey hole keeps getting better the more I look at it. I originally thought it was just a really big crocodile tooth of the species Woodbinesuchus byersmauricei, a common find for the site. After cleaning it today, I noticed it was pretty different and am now 90% sure it's a plesiosaur tooth, perhaps from the family Leptocleididae (as opposed to Polycotylidae or Elasmosauridae) and maybe with some real scientific significance! Stay with me here... Crocodile teeth are pretty common for the site. So why do I think this isn't one? Besides being quite large for a croc, the 12 enamel ridges on this specimen vary in shape and are spaced out whereas my crocs typically exhibit tightly spaced, uniform ridges numbering in the many dozens. The ridges on the "plesiosaur" are restricted to the lingual side. My crocs typically have ridges spanning the entire circumference of the crown, though they sometimes peter out on the labial side as well. Another significant difference is in the sigmoidally curved crown which is normal in plesiosaurs and generally not seen in crocs. "Plesiosaur" (L) and Croc (R); Note the significantly different enamel ridge characteristics. "Plesiosaur" and my complete crocs. Quite large relatively speaking. It's crown is about 20 mm long and 6 mm in diameter. Sigmoidal curvature in the crown. I am less sure of the familial identification and beyond. A quick google search for Cenomanian Plesiosaurs revealed an interesting article on freshwater Kem Kem Group Plesiosaurs (https://doi.org/10.1016/j.cretres.2022.105310) from more or less the same time (Woodbine = mid Cenomanian vs. Kem Kem Group = ?Albian-Cenomanian). What initially caught my eye was Fig. 5 where a handful of similar teeth are shown: Fig. 5 from the article. Leptocleididae indet. shed teeth. These are thought to be indeterminate Leptocleididae shed teeth for features shared with my specimen. The authors rule out Polycotylidae on the basis that those teeth are usually more robust. They acknowledge that longer teeth of Polycotylidae do occur, but the striations are finer than Leptocleididae. The authors contrast their teeth (and mine) from Elasmosauridae and Cryptoclididae by stating that those families have straighter teeth with more labio-lingually compressed crowns that create a strong oval cross section. My tooth and those shown above are sub-circular/slightly oval-shaped. Another point to make is that Leptocleididae plesiosaurs are UNKNOWN from deep water environments and are instead suggested to be nearshore specialists (Woodbine is famously nearshore with its crocs, Cretodus semiplicatus, and other nearshore fauna). On the other hand, Polycotylidae, the sister taxon, is a deeper water family. Hard to show a good cross-section because a chunk of root juts out of the bottom making it look more labiolingually compressed than it really is! Implications and Significance: One extremely interesting aspect of plesiosaur ecology that is highlighted by the article is their strong presence in prehistoric freshwater ecosystems. Plesiosaur teeth of the family Leptocleididae are commonly found in the Kem Kem river systems which isn't crazy given they are thought to be nearshore specialists. The authors note that contemporaneous marine deposits have yet to yield Leptocleididae material, which makes one wonder: were they freshwater specialists unable to live in the ocean? I would've been inclined to assume they could survive both fresh and salt given my preconceived notions on plesiosaurs, but there is a lack of hard proof... Until now? If this is what I think it is... this may be the first evidence of Leptocleididae found in a marine deposit contemporaneous with the Kem Kem Group! Just the missing puzzle piece emphasized in the article. Reeling it back in- Keep in mind, a few hours ago I thought this was just a big croc tooth! Also, I don't know much of anything about plesiosaurs since I had never found such material previously. My head is spinning with all these new names. Hopefully you all can provide some clarity on this matter. @pachy-pleuro-whatnot-odon @Jared C @PaleoPastels. Feel free to tag anyone else you know who might have some knowledge on the subject! Pics: ~Thanks for reading~