fossil_lover_2277 Posted November 19, 2021 Share Posted November 19, 2021 I just recently found this bone in the Cretaceous Black Creek group deposits of eastern North Carolina. I originally thought it was an oddly shaped shark vertebra, but now I think it might be a worn plesiosaur vert. based on the images I looked up online. The overall cross sectional shape is elliptical, and the center looks much too thick for shark (doesn’t pinch in towards the center). Any thoughts? Thanks! Link to comment Share on other sites More sharing options...
frankh8147 Posted November 19, 2021 Share Posted November 19, 2021 (edited) It looks like Ray to me! Edited November 19, 2021 by frankh8147 1 Link to comment Share on other sites More sharing options...
fossil_lover_2277 Posted November 19, 2021 Author Share Posted November 19, 2021 6 minutes ago, frankh8147 said: It looks like Ray to me! Wow, never seen a ray vertebra before, kinda never thought about it even though they are vertebrates. That’s so cool, thanks! 1 Link to comment Share on other sites More sharing options...
Al Dente Posted November 19, 2021 Share Posted November 19, 2021 These are usually identified as Brachyrhizodus. 1 Link to comment Share on other sites More sharing options...
fossil_lover_2277 Posted November 20, 2021 Author Share Posted November 20, 2021 8 minutes ago, Al Dente said: These are usually identified as Brachyrhizodus. I found this on Elasmo.com about Brachyrhizodus: http://www.elasmo.com/frameMe.html?file=genera/cretaceous/brachyrhizodus.html&menu=bin/menu_genera-alt.html Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted November 20, 2021 Share Posted November 20, 2021 Hah! Well whaddaya know! If found in any other context I'd have said this was definitely a plesiosaur caudal, as those too often have an elongated shape, are either platycoelous or amphicoelous, would be about this thick, not have subcentral foramina any more, nor parapophyses or hematophyses in the very terminal ones, and may have a notochordal pit. I'd moreover expect rays to have as cartiligenous skeleton, much as the other chondrichthians, and a vertebral barrel marked with struts and depressions, much like other fish, including sharks... But i guess context is everything! Still, it begs the question, how would you differentiate a vertebra like this from a plesiosaurian one? 3 'There's nothing like millions of years of really frustrating trial and error to give a species moral fibre and, in some cases, backbone' -- Terry Pratchett Link to comment Share on other sites More sharing options...
RuMert Posted November 20, 2021 Share Posted November 20, 2021 Not thick enough for a plesiosaur, looks more ichthyosaurian in 3,6,7. I'd agree with ray 1 1 My sites & reports Link to comment Share on other sites More sharing options...
fossil_lover_2277 Posted November 20, 2021 Author Share Posted November 20, 2021 28 minutes ago, pachy-pleuro-whatnot-odon said: Hah! Well whaddaya know! If found in any other context I'd have said this was definitely a plesiosaur caudal, as those too often have an elongated shape, are either platycoelous or amphicoelous, would be about this thick, not have subcentral foramina any more, nor parapophyses or hematophyses in the very terminal ones, and may have a notochordal pit. I'd moreover expect rays to have as cartiligenous skeleton, much as the other chondrichthians, and a vertebral barrel marked with struts and depressions, much like other fish, including sharks... But i guess context is everything! Still, it begs the question, how would you differentiate a vertebra like this from a plesiosaurian one? 3 minutes ago, RuMert said: Not thick enough for a plesiosaur, looks more ichthyosaurian in 3,6,7. I'd agree with ray I’ve had several people tell me ray, and several others say plesiosaur as a possibility. I don’t think Brachyrhizodus is particularly common from NC either, based on what Elasmo.com said. Not that plesiosaur is common of course. I do wish there was a definitive way to know. Link to comment Share on other sites More sharing options...
fossil_lover_2277 Posted November 20, 2021 Author Share Posted November 20, 2021 For comparison, here are some plesiosaur verts, and then the vert from this post: Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted November 20, 2021 Share Posted November 20, 2021 5 hours ago, RuMert said: Not thick enough for a plesiosaur, looks more ichthyosaurian in 3,6,7. I'd agree with ray Interestingly, ichthyosaurian was also the first impression I got when I saw the photographs, but hadn't really looked at the vertebral shape yet. Makes sense for a fish vertebra too, of course, to be thin and have a hourglass cross-section. So may be exactly that would be the defining characters based on which you can tell ray from plesiosaur: if it simultaneously looks like a plesiosaurian vertebra and an ichthyosaurian one, it's ray? In any case, hadn't seen anything like this before. Very instructional...! 1 1 'There's nothing like millions of years of really frustrating trial and error to give a species moral fibre and, in some cases, backbone' -- Terry Pratchett Link to comment Share on other sites More sharing options...
RuMert Posted November 20, 2021 Share Posted November 20, 2021 (edited) As you may check in my gallery, plesiosaur verts are usually thicker (longer) and can even be twice as long as wide. The only short plesiosaur verts I know of belong to pliosaurs, are cervical and massive in size (this is due to their big heads). Maybe in some Cretaceous deposits (e.g. NC) small short plesiosaur verts are common, but I'm not aware of them Edited November 20, 2021 by RuMert 1 My sites & reports Link to comment Share on other sites More sharing options...
Al Dente Posted November 20, 2021 Share Posted November 20, 2021 9 hours ago, fossil_lover_2277 said: I don’t think Brachyrhizodus is particularly common from NC either, based on what Elasmo.com said. Haven’t you found any Brachyrhizodus teeth at your site? I usually find a few when I screen Campanian aged lag deposits in NC. Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted November 20, 2021 Share Posted November 20, 2021 (edited) 7 hours ago, RuMert said: As you may check in my gallery, plesiosaur verts are usually thicker (longer) and can even be twice as long as wide. The only short plesiosaur verts I know of belong to pliosaurs, are cervical and massive in size (this is due to their big heads). While I agree with you that pliosaur vertebrae are typically - but certainly not always - shorter than those of plesiosauromorph plesiosaurs, I don't agree that plesiosaur vertebrae are typically longer than wide. While this is often, but - even here - not always, the case in elasmosaurs (I've got a couple of surprisingly thin Zarafasaura oceanis vertebrae in my collection, for example), Triassic and Early to Mid Jurassic plesiosaur vertebrae stree certainly not as long. I've got various Jurassic specimens in my collection, for instance, that are shorter than they are wide - the thickest reach about a 1:1 length:width ratio - and this includes caudals. I've even recently seen an American plesiosaur vertebra from Montana that had the exact same shape and thickness as Landon's specimen, but also had the subcentral foramina. So while I think vertebral thickness may be indicative, it's certainly not a determining factor... Edited November 20, 2021 by pachy-pleuro-whatnot-odon 1 'There's nothing like millions of years of really frustrating trial and error to give a species moral fibre and, in some cases, backbone' -- Terry Pratchett Link to comment Share on other sites More sharing options...
fossil_lover_2277 Posted November 20, 2021 Author Share Posted November 20, 2021 (edited) 7 hours ago, Al Dente said: Haven’t you found any Brachyrhizodus teeth at your site? I usually find a few when I screen Campanian aged lag deposits in NC. The first time I went to the place was this past Thursday. There were no Brachyrhizodus teeth that I could find, but certainly other typical Cretaceous stuff was present, as well as some other oddities. I’ve never actually found a Brachyrhizodus tooth at any of the Campanian sites I’ve tried Edited November 20, 2021 by fossil_lover_2277 Link to comment Share on other sites More sharing options...
RuMert Posted November 20, 2021 Share Posted November 20, 2021 12 minutes ago, pachy-pleuro-whatnot-odon said: While I agree with you that pliosaur vertebrae are typically - but certainly not always - shorter than those of plesiosauromorph plesiosaurs, I don't agree that plesiosaur vertebrae are typically longer than wide I meant longer than the specimen in question Longer than wide is about elasmosaurs and Co 1 My sites & reports Link to comment Share on other sites More sharing options...
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