pachy-pleuro-whatnot-odon Posted April 16, 2021 Share Posted April 16, 2021 Hi all, I've had the below piece in my collection for a number of years now, having acquired it thinking it was a juvenile plesiosaur propodial. It comes from the Oxford Clay of Peterborough and is of Callovian Jurassic age. However, when recently doing some research towards answering another question on TFF, I realised that - even though there's some plastic deformation going on - it doesn't quite look like the juvenile plesiosaur propodial I have from the rhaetic at Aust, nor does it look like a plesiosaur propodial in a more general sense (see both post and images below). There are some oddities that have started to make me wonder, in not a plesiosaur propodial, what else it may be in that case. The bone is quite dense, so is definitely marine reptile. And, since I'm quite sure it's not ichthyosaurian, this, I believe, leaves only pl(es)iosaur and teleosaur. Morphologically, the bone consists of a shaft that widens towards one end, with the other end having broken off. The widened end, top-side, forms a bit of an overhang across what appears to be an intact articulation surface, with a notch cutting into it from the right. At the broken end, also on the right, there appears to be a slight twist in the bone. This is, moreover, the side that's rounded along the length of the bone, whereas the other side appears carinated. Although there's some crushing on the underside of the bone, that surface appears markedly more flat than the obverse. It is primarily the facts that one of the edges is (more) angular and that the bone thickens towards the widening end - rather than thins out, as in a typical plesiosaur propodial - that make me feel this is not a plesiosaur (sensu lato) propodial. Unfortunately, I don't have enough qualitative reference material on teleosaurs myself (some images below) to evaluate whether they could be a candidate for the bone - such as long or girdle bones - and didn't find anything matching amongst the figures in Johnson, Young, Steel and Lepage (2015) or Young, Sachs & Abel (2018) either. So I'm left thinking may be it could be a plesiosaur ilium, as in the other post referenced above. There are definitely some features that seem to argue in its favour, such as the flat back, slight twist and widening distal end. But lacking the proximal end of the bone makes it harder to judge, and the thickening of the bone towards the widened part seems to conflict with the idea of the bone being an ilium. Still, there are very few flat narrow bones in a plesiosaur outside of its extremities... Machimosaurus sp. at the Museum voor Natuurwetenschappen in Brussels (source: Wikipedia) Thoracic region of Machimosaurus sp. at Paléospace l'Odyssée at Villers-sur-Mer Metriorhynchus superciliosus at the Paläontologische Summlung MUT Tübingen Thoracic region of Steneosaurus sp. at the Fossilienmuseum Dotternhausen Steneosaurus spp. specimens at Urweltmuseum Hauff in Holzmaden Steneosaurus sp. leg bones at the Paläontologische Sammlung MUT Tübingen 2 '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...
pachy-pleuro-whatnot-odon Posted April 16, 2021 Author Share Posted April 16, 2021 After @paulgdls's excellent post showcasing plesiosaur ilia below, I'm now re-affirmed believe my specimen is a plesiosaur ilium, possibly Cryptoclidus? However, it would all the same be great to have some confirmation. 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...
paulgdls Posted April 16, 2021 Share Posted April 16, 2021 Take a look at this Raptocleidus ilium from the Pliensbachian, as described by Mark Evans in writing his Phd thesis. 1 Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted April 16, 2021 Author Share Posted April 16, 2021 32 minutes ago, paulgdls said: Take a look at this Raptocleidus ilium from the Pliensbachian, as described by Mark Evans in writing his Phd thesis. Not entirely sure what you're saying with this, though, as my specimen is from the Oxford Clay at Peterborough (the information I got when I bought the piece, which matches its conservation). You think it's indeed an ilium then? I must say that I do see some similarities, although my piece is not as thick as the one illustrated. But that could be due to crushing similar to what you described as a frequent occurrence for pliosaurid ilia, even though I suspect mine to be a plesiosauromorph one. Also, I've probably been looking at it from an upside-down direction. For, if I look at the Raptocleidus specimen, I now think that the widening part on mine is probably the proximal articulation, while the flat distal end would then be missing from my piece... 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...
paulgdls Posted April 17, 2021 Share Posted April 17, 2021 Yes, I know its 40 million years adrift but I thought it had a number of similarities, as you suggest. In summary I believe your specimen is an ilium, although , as you know one has been proved wrong before. 1 Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted April 17, 2021 Author Share Posted April 17, 2021 3 hours ago, paulgdls said: Yes, I know its 40 million years adrift but I thought it had a number of similarities, as you suggest. In summary I believe your specimen is an ilium, although , as you know one has been proved wrong before. Thanks for the confirmation. I know it's a tricky one and it's hard to be sure - especially from photographs alone. But as I'm having a hard time making my mind up about this particular piece myself, it's good to know someone shares my opinion. So, thanks again! May be @DE&i, @PointyKnight or @Welsh Wizard could chip in, though, to see if this opinion holds any water in their mind. 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...
PointyKnight Posted April 18, 2021 Share Posted April 18, 2021 Really hard to tell, especially with a juvenile, but I'd say it indeed matches an ilium the best. Nice find! 2 Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted April 18, 2021 Author Share Posted April 18, 2021 5 hours ago, PointyKnight said: Really hard to tell, especially with a juvenile, but I'd say it indeed matches an ilium the best. Nice find! Thanks, Mien! I'm not sure whether this is still a juvenile, though, now that it's turned out - likely - to be an ilium. The juvenile element was rather something I assumed based on size and apparent lack of epiphyses when I still thought it was a propodial - a conclusion I drew may be five, six years ago now (when I had much less experience with marine reptile material). As an ilium, I think this could very well be from an adult, as there are no signs of the epiphyses/articulation surfaces not having fused... '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...
Welsh Wizard Posted April 18, 2021 Share Posted April 18, 2021 Interesting bone but tough to say especially as it looks like part is missing. A pelvic bone is most likely and it could be an ilium or even an ischium from a marine reptile. Not sure which one. I can’t get to any of my material as we are decorating and there’s loads of furniture blocking access. Link to comment Share on other sites More sharing options...
PointyKnight Posted April 19, 2021 Share Posted April 19, 2021 @pachy-pleuro-whatnot-odon Yeah you're right, I'm not entirely sure how this specific bone would scale to a full individual without measurements, and it might just appear small superficially. Plesiosaurs did have some funky things going on with bone fusion, and locomotor elements were usually among the first IIRC. So it could definitely be from a more mature individual! 1 Link to comment Share on other sites More sharing options...
DE&i Posted April 20, 2021 Share Posted April 20, 2021 (edited) Two partial juvenile cryptoclidus iliums if it helps 1st 2nd Edited April 21, 2021 by DE&i 2 Regards.....D&E&i The only certainty with fossil hunting is the uncertainty. https://lnk.bio/Darren.Withers Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted April 22, 2021 Author Share Posted April 22, 2021 On 4/20/2021 at 11:57 PM, DE&i said: Two partial juvenile cryptoclidus iliums if it helps 1st 2nd Thanks, Darren! This definitely does help! For, although it looks like your fragments both pertain to the "distal" flattened part of the ilium, whereas mine, as I now believe, represents a "proximal" end with articulation, the size of my specimen being comparable to yours suggests that it'd be a juvenile as well. Moreover, the cross-sectional and end views of your finds suggest to me that the bone densities and surface texture of the articulation are also comparable with my specimen, further building the case for it being a partial plesiosaur ilium. And not just that: if I understand the images correctly, both of your pieces carinate/have a bit of a bend at the point where the bone flattens, which I think could very well correlate to the area where there's evidence of compression at the broken off end on my specimen. No, I think these photographs were very informational. Thanks again! 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...
pachy-pleuro-whatnot-odon Posted May 17, 2021 Author Share Posted May 17, 2021 On 4/18/2021 at 5:51 PM, Welsh Wizard said: Interesting bone but tough to say especially as it looks like part is missing. A pelvic bone is most likely and it could be an ilium or even an ischium from a marine reptile. Not sure which one. I can’t get to any of my material as we are decorating and there’s loads of furniture blocking access. Sorry for only getting to responding this so late - things seem to keep getting in the way! Not sure if you're able to access your material again. But, if so, I'd still be really interested in hearing your thoughts on the specimen, if you have the time. In the meantime, however, I wanted to make my reasons for thinking the bone is plesiosaurian explicit, so that there's more of a context within which to discuss the fossil. Thalattosuchia Starting with thalattosuchia, there are a whole bunch of flat and shafted bones in the pectoral and pelvic regions that could've been a potential match for my bone. However, it appears to me that none of the shafts have the same overall shape as my bone, insofar as that the crocodilian bones have bulges, compressions or widen in ways that my specimen doesn't. Below is an overview, with all images, but three, taken from Lepage et al. (2008)'s "Catalogue descriptif, anatomique, géologique et historique des fossiles présentés à l'exposition «Les crocodiliens fossiles de Normandie»". Overview of Metriorhynchus pectoral (left) and pelvic (right) elements: sc = scapula, cor = coracoid, pu = pubis, il = ilium, is = ischium. Figure 31 from Lepage et al. (ibid., p. 68) Metriorhynchus cf. hastifer scapula. Compiled from figures 16 & 17 from Lepage et al. (ibid., p. 56) Metriorhynchus sp. right coracoid. Figure 26 from Lepage et al. (ibid., p. 67) Metriorhynchus sp. left (G) and right (D) pubis bones. Figure 27 from Lepage et al. (ibid., p. 67) Metriorhynchus sp. right ischium. Figure 28 from Lepage et al. (ibid., p. 67) Teleosaurus cadomensis right coracoid (top) and right scapula (bottom). Compiled from figures 34 and 35 from Lepage et al. (ibid., p. 148) Teleosaurus cadomensis pelvic girdle. pu = pubis, il = ilium, is = ischium. Figures 36C from Lepage et al. (ibid., p. 148) Dakosaurus carpenteri ischium. Figure 9 from Wilkinson, Young and Benton, 2008. A new metriorhynchid crocodilian (Mesoeucrocodylia: thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK Lemmysuchus obtusidens ischium (A, B), ilium (C, D) and pubis (E, F). Figure 17 from Johnson et al., 2017. Re-description of ‘Steneosaurus’ obtusidens Andrews, 1909, an unusual macrophagous teleosaurid crocodylomorph from the Middle Jurassic of England Lemmysuchus obtusidens scapula. Figure 16 from Johnson et al. (ibid.) 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...
pachy-pleuro-whatnot-odon Posted May 19, 2021 Author Share Posted May 19, 2021 Ichthyosauria The situation is greatly simplified when considering ichthyosauria as - presuming my indeed derives from the Peterborough member of the Oxford Clay, as conservation suggests - there'd be only one main genus of ichthyosaur, namely Ophthalmosaurus, to consider. This greatly reduces the diversity of shapes we'd need to verify my specimen against. And speaking of reducing, one of the hallmarks of derived ichthyosaurs are their greatly reduced pectoral and pelvic girdle elements - the pubis and ischium in particular, which, over time, merge into a single ischiopubis bone. Comparatively basal pelvic configuration as seen in Ichthyosaurus communis. Figure 60 from McGowan & Motani, 2003. Part 8: Ichthyopterygia. In: Handbook of Paleoherpetology. Different degrees of fusion between ischium and pubis bones in A. Leptonectes tenuirostris and B. cf. Ichthyosaurus communis. Figure 61 (ibid.) Greatly reduced pelvic girdle elements in A. Stenopterygius quadriscissus and B. Ophthalmosaurus icenicus. Figure 62 (ibid.) Stenopterygius sp. ischiopubis, Holzmaden. Ophthalmosaurus icenicus pelvic girdle at the Paläontologische Sammlung MUT Tübingen As I hope can be seen from the above images, my specimen doesn't particularly match an ichthyosaurian ischiopubis bone, nor would the flaring ends of it suggest the piece being an ilium. If we quickly review the ichthyosaurian pectoral girdle, then I also think there's not much there that would suggest my piece being ichthyosaurian - except for maybe the scapula. But I think my specimen is too thick and rounded for that. Reconstructed undistorted Ichthyosaurus communis pectoral girdle. Figure 56 from McGowan & Motani (ibid.) Ichthyosaurus communis scapula. Figure 58 (ibid.) Ophthalmosaurus icenicus right coracoid and scapula. Figure 59 (ibid.) Ophthalmosaurus icenicus pectoral girdles at Naturmuseum Senckenberg, Frankfurt (left) and Paläontologische Sammlung MUT Tübingen (right) Schematic and idealised pectoral (top) and pelvic (bottom) girdles of Stenopterygius and Ophthalmosaurus. Figure 70 from McGowan & Motani (ibid.). Sc = scapula, Co = coracoid, il = ilium, IP = ischiopubis '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...
pachy-pleuro-whatnot-odon Posted May 19, 2021 Author Share Posted May 19, 2021 Plesiosauria This brings us to plesiosauria, which pelvic and pectoral girdles consist primarily of flat and plate-like elements, thus also contain only very few bones that might forms a match for my specimen. Compare with the images below: Pectoral girdle of Muraenosaurus (leedsi) durobrivensis, missing the clavicle (source). Cor = coracoid, scap = scapula, dp = dorsal process, vp = ventral process Pectoral girdle of Trinacromerum sp.. Figure 102 from Williston, 1925. The Osteology of Reptiles. ic = interclavicle, cl = clavicle, sc = scapula, c = coracoid Sthenarosaurus dawkinsi pectoral girdle at the Paläontologische Sammlung MUT Tübingen (source). Ontogenetic series of the pectoral girdle of Cryptoclidus oxoniensis: A. juvenile, B. subadult, C. adult. Figure 2 from O'Keefe and Byrd, 2012. Of the shoulder in Polycotylus latipinnus (Plesiosauria: Polycotylidae) and its bearing on plesiosaur viviparity Indeterminate plesiosaurian pelvic girdle (source) Reconstructed pelves of A. Muraenosaurus, B. Cryptoclidus and C. Tatenectes. Figure 6 from O'Keefe et al., 2011. A new skeleton of the cryptoclidid plesiosaur Tatenectes laramiensis reveals a novel body shape among plesiosaurs Right ilium of a fetal Polycotylus. Figure 7 from O'Keefe and Byrd (ibid.) Especially the last two images convince me that my piece is a fragment of plesiosaurian ilium, based on the the roundness, way the bone flares out and articulates with the ischium. Below is the image of a juvenile cryptoclidid on exhibit at Stuttgart's Naturkundemuseum/Museum am Löwentor with an ilium that I believe matches my specimen both in shape and mode of conservation quite closely. '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 May 19, 2021 Share Posted May 19, 2021 You turned this thread into a big source of information What do you think of this one? IDable? My sites & reports Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted May 19, 2021 Author Share Posted May 19, 2021 1 hour ago, RuMert said: You turned this thread into a big source of information What do you think of this one? IDable? Hahaha! Thanks, Yury! Always the opportunist too, right? Unfortunately, having compiled all of this information doesn't make me an expert on these bones, as I've simply still seen and held too few of them... That having been said, I'd say that the concave back side and rounded front of the bone are diagnostic in limiting your specimen to either an ichthyosaur podial, plesiosaur ilium or thalattosuchian scapula, as all three have the mentioned features and most of the other pelvic and pectoral bones of these groups don't. I doubt it would be an ichthyosaur podial, though, due to the end of the bone being so rounded, rather than angular/polygonal to fit various carpalia/tarsalia, as is usual of ichthyosaurs of that age (Kimmeridgian, by the looks of it?). Also, as I haven't heard too much about thalattosuchia from Russia, I'm assuming these are relatively rare - which would make sense, seeing as there were so many other apex-predators (i.e., pliosaurs) around. In other words, my current best bet would be, again, a pl(es)iosaur ilium, distal end. 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 May 19, 2021 Share Posted May 19, 2021 Wow that was swift, thanks My sites & reports Link to comment Share on other sites More sharing options...
RuMert Posted May 19, 2021 Share Posted May 19, 2021 And this one, what do you think? Same location My sites & reports Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted May 20, 2021 Author Share Posted May 20, 2021 11 hours ago, RuMert said: And this one, what do you think? Same location The way the one end is round and the other flattened, plus the slight distinction (on the rounded end) of more spongious bone surrounded by denser bone makes me think this is a section of plesiosaur propodial, probably pliosaur for the number of specimens found in comparison to plesiosauromorph, as well as the way your bone flattens reminds me of the propodials of Peloneustes philarchus. Whether it is a fragment of a humerus or femur is impossible to say as the piece isn't big enough to include the site from which presence or absence of the trochanter could inform you as to this question. Cross-sections through a plesiosaur (left; Sandsend, Whitby) and pliosaur (right; Abingdon) propodial. NB.: these cross-sections were taken much further up the shaft than your piece would be from, so are less compressed. 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 May 20, 2021 Share Posted May 20, 2021 Thanks, that's what I thought initially, but something in the shape made me doubt. Maybe too flattened and curved. My sites & reports Link to comment Share on other sites More sharing options...
pachy-pleuro-whatnot-odon Posted May 20, 2021 Author Share Posted May 20, 2021 7 minutes ago, RuMert said: Thanks, that's what I thought initially, but something in the shape made me doubt. Maybe too flattened and curved. Nah. Though you're right in that the end typically remains somewhat thicker than in your specimen, I've got two propodials from the Oxford Clay here that show exactly the same degree of flattening towards the distal end. Also, the curvature is due to one side of the propodial flaring out more than the other - again a feature shared with my specimens... '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...
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