A pair of sauropod verts

[FF7_Yuffie]

Hello,

 

I am interested in these, sold as Cetiosaur. From Abingdon. Sauropod fossils are found there, but a lot sold are plesiosaur/pliosaur verts that are misidentified. So if anyone could take a look and give your thoughts on these, that would be great. The centrum shape doesn't resemble the shape of the sauropod vert I have from that fromation, but it could easily be from a different species or something. Anyone, two verts.

 

1st one -- 7.5cm by 3.5 cm.

 

 

[FF7_Yuffie]

Vertebra number 2 - same location

 

9cm by 4.5 cm

 

 

Any help,much appreciated as always.

[Welsh Wizard]

Hi

 

Apologies for the short answer but the first one looks like an ichthyosaur vert and the second one looks like it’s from a plesiosaur/pliosaur-largely due to those small holes at the base.

 

N

 

 

[belemniten]

4 hours ago, Welsh Wizard said:

Hi

 

Apologies for the short answer but the first one looks like an ichthyosaur vert and the second one looks like it’s from a plesiosaur/pliosaur-largely due to those small holes at the base.

 

N

 

 

Both look like plesiosaur/pliosaur verts. I have only seen concave ichthyo verts until now. 

[pachy-pleuro-whatnot-odon]

As I haven't handled any sauropod vertebrae, it's difficult for me to give you a definite or comparative answer. But the second vertebra it's unmistakably a plesiosaurian one. The heart-shape of the centrum in axial view, but especially the presence of nutritive foramina on the ventral side give it away.

 

The first vertebra is more difficult to identify, as it's so worn. I highly doubt it's sauropod, though, as 1) the vertebra is rather flat for a sauropod (going on images I could find online); 2) the vertebra is not constricted, or waisted,  across its length; and 3) Cetiosaurus vertebra, as far as I can tell, have square outlines to their vertebral centra when viewed axially.

 

Whether the vertebra is ichthyosaur or plesiosaur instead, I find a bit of a hard call, though, as the vertebra seems too wide for an ichthyosaur vertebra (ichthyosaur vertebra typically are taller than they are wide), and also appears to lack the concave sides so typical of ichthyosaurs. That having been said, Brachypterygius extremus is the only species of ichthyosaur know from Abingdon, and occasionally has very minor depressions in its vertebral centra, which one could easily imagine eroding away. And while the width/height to depth ratio of the vertebra in some of the images look very much like what you'd expect of an ichthyosaur vertebra, in most others it appears too thick for a derived/thuniform species such as B. extremus. Add to that the broad dorsal surface and large area for attachment of the neutral arch, which looks more plesiosaur than ichthyosaur, I'd say this too is a plesiosaurian vertebra - even if no trace of nutritive foramina remains. I thus support Belemniten's conclusion...

[jpc]

The second one is definitely plesiosaur... as mentioned above... nutrient foramina at the base gives it away.  I think the first one os too, but that is just my hunch. 

[FF7_Yuffie]

Thanks for the help, everyone. I had my doubts from the start, so many sauropod verts from this area are actually pliosaur and plesiosaur. Glad to get it verified, and I know more of what to look for---the two holes I know are characteristic of plesiosaur, so sauropod verts don't have them at all?

 

Thanks for taking a look and for the help.

[Welsh Wizard]

11 hours ago, belemniten said:

Both look like plesiosaur/pliosaur verts. I have only seen concave ichthyo verts until now. 

yes, your probably right but it is quite thin as a plesiosaur centrum.

[Welsh Wizard]

6 hours ago, FF7_Yuffie said:

Thanks for the help, everyone. I had my doubts from the start, so many sauropod verts from this area are actually pliosaur and plesiosaur. Glad to get it verified, and I know more of what to look for---the two holes I know are characteristic of plesiosaur, so sauropod verts don't have them at all?

 

Thanks for taking a look and for the help.

it is tough with these verts as they can be distorted with bits missing making them hard to identify. 
 

it is also quite easy to confuse plesiosaur and certain dinosaur verts.

 

with respect to the holes, they definitely appear in plesiosaur/pliosaur verts as symmetrical paired holes. You do get small holes in dinosaur verts but they seem less pronounced and less obviously symmetrical but as with everything, there are exceptions. You also get large holes or pleurocels in certain dinosaur verts but they tend to be quite pronounced.
 

ive asked various people about some of the verts I’ve got and you do get mixed views even from the experts.

[pachy-pleuro-whatnot-odon]

34 minutes ago, Welsh Wizard said:

yes, your probably right but it is quite thin as a plesiosaur centrum.

Pliosaur vertebrae are often a lot thinner, though. Not sure why that is - whether it's preservational or has to do with their stockier body plan - and you'll definitely will come across more traditionally plesiosaurian looking ones, but there first vertebra is certainly not too thin for pliosaur. See pp. 181 (36) & 183-184 (38-39) of Tarlo's (1960) "A review of Upper Jurassic Pliosaurs".

[Welsh Wizard]

18 minutes ago, pachy-pleuro-whatnot-odon said:

Pliosaur vertebrae are often a lot thinner, though. Not sure why that is - whether it's preservational or has to do with their stockier body plan - and you'll definitely will come across more traditionally plesiosaurian looking ones, but there first vertebra is certainly not too thin for pliosaur. See pp. 181 (36) & 183-184 (38-39) of Tarlo's (1960) "A review of Upper Jurassic Pliosaurs".

Thanks. Looks an interesting paper. Most of my plesiosaur stuff is lower Jurassic/Triassic and the height thickness ratio tends to be closer to 1 whereas the ichthyosaur verts tend to be a lot thinner.

 

The hockey puck analogy for ichthyosaurs and cotton reel analogy for plesiosaurs tends to hold largely true but there are exceptions.

 

It would be interesting to see if there are papers on the fauna of the Kimmeridge of Oxford as a lot of material is coming to market.

 

There were certainly some massive ichthyosaurs in this fauna. I’m not sure if you’ve seen the humerus I posted in the “my collection” section?

[pachy-pleuro-whatnot-odon]

1 hour ago, Welsh Wizard said:

with respect to the holes, they definitely appear in plesiosaur/pliosaur verts as symmetrical paired holes. You do get small holes in dinosaur verts but they seem less pronounced and less obviously symmetrical but as with everything, there are exceptions. You also get large holes or pleurocels in certain dinosaur verts but they tend to be quite pronounced.

This is exactly the reason I had to be a bit more reserved about my own answer, as I've simply not seen enough sauropod vertebral material to be able to say whether you'd find foramina in these bones, and how they would look. Good to know that they are there but either are less obvious or larger than those in plesiosaurians and not necessarily paired - that is, they may be there, but less structurally so (in various meanings of the word). For, though they are indicative of plesiosaur vertebrae in a marine context, they're certainly not restricted to them...

 

7 hours ago, FF7_Yuffie said:

Glad to get it verified, and I know more of what to look for---the two holes I know are characteristic of plesiosaur

Wintrich, Scaal & Paul's (2017) "Foramina in plesiosaur cervical centra indicate a specialized vascular system", from which the below illustration (figure 3) was taken, describe the nature of these foramina, their origin in embrionic stages of plesiosaur development, and suggested adaptive advantages related to thermoregulatory functions during deep dives.

 

 

It is important to note, though, that, because of what these authors describe in their paper, you may also find a constellation of foramina on the dorsal side of plesiosaurian vertebrae, located on the inside of the neural canal, as evidenced in the Colymbosaurus trochanterius vertebra below (here seen dorsally):

 

[pachy-pleuro-whatnot-odon]

1 hour ago, Welsh Wizard said:

It would be interesting to see if there are papers on the fauna of the Kimmeridge of Oxford as a lot of material is coming to market.

Martill and Hudson's 1996 "Fossils of the Oxford Clay" may be a good place to start, though their description and illustration of marine reptile remains is rather minimal, if instructive...

[pachy-pleuro-whatnot-odon]

12 hours ago, Welsh Wizard said:

There were certainly some massive ichthyosaurs in this fauna. I’m not sure if you’ve seen the humerus I posted in the “my collection” section?

Haha! So it ended up with you, then? I wanted to buy it exactly the same time as you (one of those fossils you buy without hesitating even a second): it still showed as unsold when I clicked to pay for it, then got an error that something wasn't working out with the purchase. After some emailing, it turned out to have been sold at the exact time I'd pressed "buy"! Was quite disappointed about missing that one too, as I had tried to purchase a B. extremus humerus before (albeit a smaller one), which  turned into one of the only occasions I've ever lost something in the mail

 

But it's a beauty and a giant one, isn't it? Glad it ended up in your impressive collection!

 

[FF7_Yuffie]

Thanks for the infi, everyone. Appreciated.

 

So, just to check that I've understood. With the clear holes in this vert and the verts shape, I can safely put this cetiosaur vert on the not a cetiosaur pile too.

 

Cheers for info. I must have posted 8+ uk sauripod verts here and had just one hit as an actual sauropod lol

[paulgdls]

I agree with all the above comments. The sub central foramina on the second specimen (and the last one posted) are paired and thus its definitely plesiosaurid. I've been talking to Steve Etches about these offerings over the past weeks (and there are lots of them). He agrees that, without exception, the items being sold are plesiosaur/pliosaur not dinosaur. As you may know there has been an ongoing debate about some giant centra in Peterborough museum. Opinions swing between giant pliosaur and cetiosaur. I believe the latest paper is in favour of cetiosaur but I'm not convinced. There must have been bigger pliosaurs out there, yet to be discovered. I've got a massive bone which I believe to be a pliosaur scapula (see photos below). It 3.5 times bigger than the equivalent Simolestes vorax in my collection (see photos). Opinions and comments welcomed. 

 

Paul

 

 

[pachy-pleuro-whatnot-odon]

8 hours ago, FF7_Yuffie said:

Thanks for the infi, everyone. Appreciated.

 

So, just to check that I've understood. With the clear holes in this vert and the verts shape, I can safely put this cetiosaur vert on the not a cetiosaur pile too.

 

Cheers for info. I must have posted 8+ uk sauripod verts here and had just one hit as an actual sauropod lol

 

2 hours ago, paulgdls said:

The sub central foramina on the second specimen (and the last one posted) are paired and thus its definitely plesiosaurid.

 

2 hours ago, paulgdls said:

I've been talking to Steve Etches about these offerings over the past weeks (and there are lots of them). He agrees that, without exception, the items being sold are plesiosaur/pliosaur not dinosaur.

Although I must say I haven't seen that much Abingdon material pass by my radar on the odd ten sites I check almost daily... Then again, may be I haven't been paying attention to it, as I'm currently focussed on some other materials: Triassic, at present - and always marine reptiles anyway, never dinosaurs...

[Welsh Wizard]

9 hours ago, paulgdls said:

I agree with all the above comments. The sub central foramina on the second specimen (and the last one posted) are paired and thus its definitely plesiosaurid. I've been talking to Steve Etches about these offerings over the past weeks (and there are lots of them). He agrees that, without exception, the items being sold are plesiosaur/pliosaur not dinosaur. As you may know there has been an ongoing debate about some giant centra in Peterborough museum. Opinions swing between giant pliosaur and cetiosaur. I believe the latest paper is in favour of cetiosaur but I'm not convinced. There must have been bigger pliosaurs out there, yet to be discovered. I've got a massive bone which I believe to be a pliosaur scapula (see photos below). It 3.5 times bigger than the equivalent Simolestes vorax in my collection (see photos). Opinions and comments welcomed. 

 

Paul

 

 

Thanks Paul

 

Good to hear from you.

 

I’d agree but I’d also add that dinosaur material does come out of these deposits. I’ve got some stuff that I’ve picked up over the years but the centra are so hard to identify.

 

Ive got some big ones with a raised area in the centre of one face and a slight depression in the other. They are not concave/convex verts but the face has this raised feature. Looking at papers, I’ve seen similar features in some elasmosaur verts but the uk verts can be massive.

 

Nick

[pachy-pleuro-whatnot-odon]

9 hours ago, paulgdls said:

I've got a massive bone which I believe to be a pliosaur scapula (see photos below). It 3.5 times bigger than the equivalent Simolestes vorax in my collection (see photos). Opinions and comments welcomed. 

 

Paul

 

 

I've seen these photographs a number of times in different places now (e.g., here), and as impressed as I am by its enormous size, the idea that it might be part of a pliosaur scapula, and by how big of an animal this would've needed to come from, I'm having great difficulty visualising the three-dimensional shape of the bone from just the photographs alone. In fact, I find the bone lying atop - i.e., the S. vorax scapula - also very difficult to identify for what it is. The problem - apart from a fragment always being more difficult to identify, of course - is that a lot of the images available from literature actually are line drawings, rather than showing the actual bones, and that these bones, in museums, are frequently exhibited as part of full skeletal displays. As such, it's hard to get a good look at them anywhere, unless you yourself have been involved with either the preparation, setup or dismanteling of the skeleton in question.

 

I did identify the below piece of bone in my collection as a fragment of the scapula of an indeterminate pliosaur based on comparison with figure 5 from Tarlo's 1960 "A review of Jurassic pliosaurs"; a series of photographs of Peloneustes philarchus' pectoral girdle at the Naturmuseum Senckenberg in Frankfurt (also below); and the general notions that 1) pectoral and pelvic girdle elements are flat, 2) are some of the only flat bones in a plesiosaurian skeleton, and 3) the scapula is the only bone amongst the girdle elements that exhibits a difference in levels within a single bone. But I still consider this identification tentative, since the argumentation is so flimsy and the bone itself offers little in terms of other diagnostic features.

 

 

 

 

 

 

 

Looking at your specimen, and especially the below to photographs, I can certainly see where your proposition of it being a scapula comes from. It's just that most pliosaurs have so many of these notches along the edges of their pectoral and pelvic bones that, as with my specimen, without a point on the fragment that can be used as a reference point or anchor on a more complete and well-attributed specimen, it'll be hard to say anything with certainty. However, the fact that part of your fragment exhibits an incline I think is telling - even if I lack experience with sauropod and other dinosaur material to estimate whether this is indeed significant enough for differentiation between the dinosaurian and marine reptile options... If I look at the internal bone structure of your specimen, though, it looks much more osteosclerotic than I would expect for sauropod or theropod bone, as I understand these are typically quite pneumatised.

Quote

 

I hope these ideas are of any help

[paulgdls]

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

I've seen these photographs a number of times in different places now (e.g., here), and as impressed as I am by its enormous size, the idea that it might be part of a pliosaur scapula, and by how big of an animal this would've needed to come from, I'm having great difficulty visualising the three-dimensional shape of the bone from just the photographs alone. In fact, I find the bone lying atop - i.e., the S. vorax scapula - also very difficult to identify for what it is. The problem - apart from a fragment always being more difficult to identify, of course - is that a lot of the images available from literature actually are line drawings, rather than showing the actual bones, and that these bones, in museums, are frequently exhibited as part of full skeletal displays. As such, it's hard to get a good look at them anywhere, unless you yourself have been involved with either the preparation, setup or dismanteling of the skeleton in question.

 

I did identify the below piece of bone in my collection as a fragment of the scapula of an indeterminate pliosaur based on comparison with figure 5 from Tarlo's 1960 "A review of Jurassic pliosaurs"; a series of photographs of Peloneustes philarchus' pectoral girdle at the Naturmuseum Senckenberg in Frankfurt (also below); and the general notions that 1) pectoral and pelvic girdle elements are flat, 2) are some of the only flat bones in a plesiosaurian skeleton, and 3) the scapula is the only bone amongst the girdle elements that exhibits a difference in levels within a single bone. But I still consider this identification tentative, since the argumentation is so flimsy and the bone itself offers little in terms of other diagnostic features.

 

 

 

 

 

 

 

Looking at your specimen, and especially the below to photographs, I can certainly see where your proposition of it being a scapula comes from. It's just that most pliosaurs have so many of these notches along the edges of their pectoral and pelvic bones that, as with my specimen, without a point on the fragment that can be used as a reference point or anchor on a more complete and well-attributed specimen, it'll be hard to say anything with certainty. However, the fact that part of your fragment exhibits an incline I think is telling - even if I lack experience with sauropod and other dinosaur material to estimate whether this is indeed significant enough for differentiation between the dinosaurian and marine reptile options... If I look at the internal bone structure of your specimen, though, it looks much more osteosclerotic than I would expect for sauropod or theropod bone, as I understand these are typically quite pneumatised.

 

I hope these ideas are of any help

 

Thank you for all your excellent observations on this. Very well thought through and reasoned if you don't mind me saying so.

 

I have gone through many of the same thought processes that you have used.  Yes, I agree there are very few photos and illustrations to work with. Your section of bone does look like pliosaur scapula. I visited the NHM and examined the Liopleurodon type specimen scapula and was able to handle it and photograph it. Unfortunately it is rather crushed but I came to the conclusion that my large specimen is more like Simolestes. Subsequently I found a disarticulated skeleton of Simolestes and was able to compare the scapulae directly. This is a difficult process as there is a vertebra sitting on top of the R100 (Simolestes) scapula, which is in a bone block but exposed on its edge. Please see an annotated diagram below which I have just done which I hope explains why I think the gross morphology is the same. 

 

I also attach a photo of a Cetiosaur scapula. This looks very different and all the sauropod scapulae seem to have a considerably curved acetabulum, whereas my large bone has a quite flattish articular surface. Please see skeleton of Liopleurodon Rossicus below which has a similar shaped scapula, I believe. Also see the stegosaur sacrum from Swindon, Wiltshire. This has the articular surfaces extended greatly laterally. It also shows the sacral rib attachment extensions on the ilia. These do not seem to be present on my bone or any sign of them. 

 

I agree that the bone structure is similar to that of large pliosaurs. Certainly sauropods and theropods  usually show extensive pneumatic chambers and cavities. I'm not sure about Cetiosaurus though. 

 

Lastly the ventral ridge seems to be highly diagnostic. 

 

Let me know your thoughts on this rambling.

 

 

[pachy-pleuro-whatnot-odon]

On 1/12/2021 at 5:41 PM, paulgdls said:

Your section of bone does look like pliosaur scapula. I visited the NHM and examined the Liopleurodon type specimen scapula and was able to handle it and photograph it. Unfortunately it is rather crushed but I came to the conclusion that my large specimen is more like Simolestes. Subsequently I found a disarticulated skeleton of Simolestes and was able to compare the scapulae directly.

Oh wow! That must've been quite the experience, handling such (by now) iconic material! And that only to be beat by actually finding a skeleton yourself - even if disarticulated! As said, I've seen your photographs on Twitter, and, boy, do they make me envious...! I mean, not that there's a lack of members with such experiences here on TFF, but I just wish I would have more opportunity to go out looking for marine reptile material and make such (lets start with: any) discoveries myself... I the meantime, however, I'm more of what I guess you'd call "an armchair enthusiast"...

Also, thanks for confirming my specimen for me: with so little usable material to compare against, identifying such pieces is always a bit tricky

 

On 1/12/2021 at 5:41 PM, paulgdls said:

Please see an annotated diagram below which I have just done which I hope explains why I think the gross morphology is the same.

Thanks for putting this together! The diagram really helps, as I think I've been looking at the S. vorax scapula all wrong up until this time But now that's cleared out of the way, the similarities between the two pieces are undeniably striking - to the extent that I'd indeed say they are the same bone, the one just being about ten times larger than the other...!

 

When considered together with the compact bone structure already commented upon, I think your identification of the dorsal process and ventral ridge are compelling arguments for the specimen truly being that of a pliosaur scapula; I agree that the morphology of the bone doesn't very much seem to match that of a Cetiosaurus scapula nor a dinosaurian pelvic element - although I admittedly have little experience with either. Especially your comparison with the three-dimensionally better preserved "Liopleurodon rossicus" scapula (hasn't this been changed to Pliosaurus rossicus?) is quite convincing, and certainly makes for a much easier juxtaposition than does the crushed Simolestes vorax scapula pictured on plate 27 (below) of Tarlo (1960) (though I believe you're acquainted with this plate already ).

 

 

I do think, though, that what you've marked as an articular surface in your diagram is actually a break in the bone, going by the surface texture visible there. To me, it much more resembles the internal vascular structure of cancellous bone, rather than the bumpy face of an articular surface. I'd also not expect the articular surface of a scapula to be as broad, seeing as the articulation would normally lie at the extremity of one of the three processes comprising the scapula. This too doesn't seem to be the case in your specimen. I've therefore drawn a line on the photograph of the P. rossicus scapula you posted above to indicate the approximate place I think your bone might be broken at (with the left-hand side remaining).

 

 

With all that, however, I'm having difficulty interpreting the reverse of specimen. For, although the obverse discussed above shows clear similarities to a pliosaur scapula, this shape is way less obvious on the underside. Below is an attempt I made at interpreting it. But as the lines will hopefully show, either I'm reading the fossils wrongly, or significant parts would need to have broken off at the top or bottom of the scapula, leaving just the single process that would then be the part marked between the top and bottom solid red lines... The dotted red line is simply where I thought I saw the shape of the bone lead to... May be you can elucidate a bit more on how the bone is structured on that side?

 

[paulgdls]

On 17/01/2021 at 11:23 PM, pachy-pleuro-whatnot-odon said:

Oh wow! That must've been quite the experience, handling such (by now) iconic material! And that only to be beat by actually finding a skeleton yourself - even if disarticulated! As said, I've seen your photographs on Twitter, and, boy, do they make me envious...! I mean, not that there's a lack of members with such experiences here on TFF, but I just wish I would have more opportunity to go out looking for marine reptile material and make such (lets start with: any) discoveries myself... I the meantime, however, I'm more of what I guess you'd call "an armchair enthusiast"...

Also, thanks for confirming my specimen for me: with so little usable material to compare against, identifying such pieces is always a bit tricky

 

Thanks for putting this together! The diagram really helps, as I think I've been looking at the S. vorax scapula all wrong up until this time But now that's cleared out of the way, the similarities between the two pieces are undeniably striking - to the extent that I'd indeed say they are the same bone, the one just being about ten times larger than the other...!

 

When considered together with the compact bone structure already commented upon, I think your identification of the dorsal process and ventral ridge are compelling arguments for the specimen truly being that of a pliosaur scapula; I agree that the morphology of the bone doesn't very much seem to match that of a Cetiosaurus scapula nor a dinosaurian pelvic element - although I admittedly have little experience with either. Especially your comparison with the three-dimensionally better preserved "Liopleurodon rossicus" scapula (hasn't this been changed to Pliosaurus rossicus?) is quite convincing, and certainly makes for a much easier juxtaposition than does the crushed Simolestes vorax scapula pictured on plate 27 (below) of Tarlo (1960) (though I believe you're acquainted with this plate already ).

 

 

I do think, though, that what you've marked as an articular surface in your diagram is actually a break in the bone, going by the surface texture visible there. To me, it much more resembles the internal vascular structure of cancellous bone, rather than the bumpy face of an articular surface. I'd also not expect the articular surface of a scapula to be as broad, seeing as the articulation would normally lie at the extremity of one of the three processes comprising the scapula. This too doesn't seem to be the case in your specimen. I've therefore drawn a line on the photograph of the P. rossicus scapula you posted above to indicate the approximate place I think your bone might be broken at (with the left-hand side remaining).

 

 

With all that, however, I'm having difficulty interpreting the reverse of specimen. For, although the obverse discussed above shows clear similarities to a pliosaur scapula, this shape is way less obvious on the underside. Below is an attempt I made at interpreting it. But as the lines will hopefully show, either I'm reading the fossils wrongly, or significant parts would need to have broken off at the top or bottom of the scapula, leaving just the single process that would then be the part marked between the top and bottom solid red lines... The dotted red line is simply where I thought I saw the shape of the bone lead to... May be you can elucidate a bit more on how the bone is structured on that side?

 

 

Hi

 

Firstly, yes it was great to be able to handle the type specimens, although I was ticked off for looking at the scapula on top of a filing cabinet. We examined the Stewartby symphysis which is simply unimaginably huge and probably equates to the size of my scapula. It weighs about 15 kg - yes, just the symphysis! Dave Martill coined the word Megapleurodon to describe what he believed existed out there from fragmentary remains, but couldn't prove it. 

 

Thank you for all your detailed observations which are a great help. I'm glad you agree with my theory. 

 

Re. the obverse (dorsal?) side of the specimen, please see additional photos below. I had the matrix removed on that side to reveal the bone. The matrix on the other side has been cleaned off as far as possible too at this stage and reduced to a couple of inches thick. This has reduced the weight of the specimen to something manageable. As found it weighed 57 kg and I was only just able to carry it for any distance!  

 

Regarding the articular surface, you are right. Part of it is broken off revealing the bone structure. On the section that is unbroken there are four depressions of unknown origin.

 

Let me know your thoughts on all this.

 

 

Paul

 

[pachy-pleuro-whatnot-odon]

On 1/19/2021 at 4:40 PM, paulgdls said:

Firstly, yes it was great to be able to handle the type specimens, although I was ticked off for looking at the scapula on top of a filing cabinet. We examined the Stewartby symphysis which is simply unimaginably huge and probably equates to the size of my scapula. It weighs about 15 kg - yes, just the symphysis! Dave Martill coined the word Megapleurodon to describe what he believed existed out there from fragmentary remains, but couldn't prove it.

Hahaha! I can only imagine you standing there examining such an important specimen, and somebody staring at you with a shocked look upon their face as to what you're doing with it!

But, wow! To get to see and handle such important specimens up close...
That having been said, I've got some pretty similar experiences (albeit in a slightly different field) from my time as an archaeology student, most notably during study visits to the depot of the Ethnologisches Museum in Berlin-Dahlem (soon to be the Humboldt Forum) and the Universidad Complutense de Madrid.

 

On 1/19/2021 at 4:40 PM, paulgdls said:

Thank you for all your detailed observations which are a great help. I'm glad you agree with my theory.

Don't thank me yet! One of the main reasons I wanted to see the other side (I previously used "obverse" versus "reverse", as these are relative terms free from the interpretation "dorsal" and "ventral" imply) is that it looked so unclear to me so as to expect it might change my opinion about the fossil as a whole. And, indeed, I'm afraid it has, as the slope that the bone makes at the point with the four impressions doesn't seem, to me, to correlate with what I'd expect of a pliosaur scapula. I mean, if it were a scapula, then we've already got one upright side, perpendicular to the plane containing the rest of the scapular bone - that is, the part you previously identified as the dorsal process - and I would, therefore, only expect the bone to fold at its edges, where the dorsal plane transitions into the ventral one. This doesn't seem to be the case here...

 

On 1/19/2021 at 4:40 PM, paulgdls said:

In order to rule out plastic deformation as a cause for the slope in this part of the bone, I think it would be good to discuss my interpretation of the four impressions now. First off all, as they were previously still covered by matrix, I think we can safely rule out any modern causes for them. It also seems unlikely to me that they can be attributed to Teredo worms, or the likes, as the holes appear too ordered/aligned for individual agency and, moreover, the angle at which the impressions were made seems very consistently strait. Instead, it looks like the holes can be divided into two groups: smaller ones on the left and larger ones on the right. As such, I believe these to be puncture marks, in two horizontal lines, each having been made by a combination of a bigger and smaller tooth. Furthermore, as both of these lines lie so closely together, and follow exactly the same pattern, I propose these impressions were not made by the bite of an entire mouth, but rather just one side twice: I imagine an animal having grabbed the bone in its jaws, not having gotten a good enough grip, loosening the grip, and then clamping down on the bone a second time.

 

In support of this hypothesis, the bite-marks lie in their own, narrower depression, which I propose represents the perimortem crushing of the bone from the bite-force. This meaning deformation of the bone due to the bite is spatially restricted. And since this spot can be clearly identified on the bone, even though the local deformation appears rather minimal, it suggest that there's little to no plastic deformation in the surrounding area of the bone.

 

Thus having established the bone has maintained its original shape, I must say that this side of the bone much more reminds me of a coracoid, such as that in the drawing below, with the bone being much thinner on opposite sides of the tubercle running the horizontal length of the bone and connecting to the area you previously identified, on the obverse, as the "dorsal process" (please note that exactly this area is also visible as a gap between the two coracoids below).

 

Dorsal view of the pectoral girdle of Trinacromerum. Figure 102 from Williston, 1925. The Osteology of the Reptiles

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Now, I realise that Trinacromerum was a Late Cretaceous polycotylid from North America, and may as such may not appear immediately applicable as an analogue here. However, the below photographs of the Liopleurodon ferox specimen at the Paläontologische Sammlung of the MUT Tübingen illustrates that British Oxfordian pliosaurs from the also had them, and that they are, in fact, rather prominent.

 

 

In fact, this appears to be an ancestral trait, with even such early species as the Sthenarosaurus, a rhomealosaurid pliosaur, of which the below two photographs illustrate a specimen found in the Pliensbachian of Nancy, also from the collections in Tübingen.

 

 

The nature of the tubercle seems to be congeneric, however, as the tubercle of Peloneustes philarchus appears way less robust than that of L. ferox. As such, If I'm correct in my assumptions on your fossil being that of a pliosaur coracoid, then it may well be of L. ferox.

 

 

Peloneustes philarchus specimens in the Paläontologische Sammlung of the MUT Tübingen (l) and Naturmuseum Senckenberg in Frankfurt (r)

 

 

 

 

 

 

 

 

 

 

Something else that may be of interest in this context is the below fragments of bone found in the Kimmeridgian of the Boulonnais (France) by a friend of mine, originally from a single bone but broken on extraction. To my mind there are various similarities here to your bone, if only the "dorsal process". He had it put down as a pelvic bone. But during our communications, the possibility of the specimen being a coracoid was also raised - although the bone's fragmentary nature left the exact origin of the specimen unclear in the end...

 

 

I hope this helps!

Cheers,
Alexander.

[paulgdls]

On 23/01/2021 at 9:49 PM, pachy-pleuro-whatnot-odon said:

Hahaha! I can only imagine you standing there examining such an important specimen, and somebody staring at you with a shocked look upon their face as to what you're doing with it!

But, wow! To get to see and handle such important specimens up close...
That having been said, I've got some pretty similar experiences (albeit in a slightly different field) from my time as an archaeology student, most notably during study visits to the depot of the Ethnologisches Museum in Berlin-Dahlem (soon to be the Humboldt Forum) and the Universidad Complutense de Madrid.

 

Hi Alexander

 

Yes, it was a bit embarrassing as the person complaining was the head of collections! Mind you, when I was in Cairo a couple of years ago  I saw a man carrying the Naqada plaque in his hands, having just unscrewed a cabinet to move material to the new mega museum. I asked him how much he wanted for it and he said $10M dollars. Such is the Egyptian way of doing things. 

 

Interesting about your studies in student days. Did you handle any Neanderthal material?

 

 

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Don't thank me yet! One of the main reasons I wanted to see the other side (I previously used "obverse" versus "reverse", as these are relative terms free from the interpretation "dorsal" and "ventral" imply) is that it looked so unclear to me so as to expect it might change my opinion about the fossil as a whole. And, indeed, I'm afraid it has, as the slope that the bone makes at the point with the four impressions doesn't seem, to me, to correlate with what I'd expect of a pliosaur scapula. I mean, if it were a scapula, then we've already got one upright side, perpendicular to the plane containing the rest of the scapular bone - that is, the part you previously identified as the dorsal process - and I would, therefore, only expect the bone to fold at its edges, where the dorsal plane transitions into the ventral one. This doesn't seem to be the case here...

 

 

Yes, the slope is a bit strange. There was some matrix in that area which could have led to crushing. 

 

 

 

 

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In order to rule out plastic deformation as a cause for the slope in this part of the bone, I think it would be good to discuss my interpretation of the four impressions now. First off all, as they were previously still covered by matrix, I think we can safely rule out any modern causes for them. It also seems unlikely to me that they can be attributed to Teredo worms, or the likes, as the holes appear too ordered/aligned for individual agency and, moreover, the angle at which the impressions were made seems very consistently strait. Instead, it looks like the holes can be divided into two groups: smaller ones on the left and larger ones on the right. As such, I believe these to be puncture marks, in two horizontal lines, each having been made by a combination of a bigger and smaller tooth. Furthermore, as both of these lines lie so closely together, and follow exactly the same pattern, I propose these impressions were not made by the bite of an entire mouth, but rather just one side twice: I imagine an animal having grabbed the bone in its jaws, not having gotten a good enough grip, loosening the grip, and then clamping down on the bone a second time.

 

In support of this hypothesis, the bite-marks lie in their own, narrower depression, which I propose represents the perimortem crushing of the bone from the bite-force. This meaning deformation of the bone due to the bite is spatially restricted. And since this spot can be clearly identified on the bone, even though the local deformation appears rather minimal, it suggest that there's little to no plastic deformation in the surrounding area of the bone.

 

As you say the marks are certainly not modern, as they were under some adherent matrix. Its intriguing to think they might be bites. Certainly the edges of the holes are very well defined. I might try and remove some of the matrix, but I think its too hard. The glenoid would be a good place to a predator to bite in order to immobilise the animal. 

 

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Thus having established the bone has maintained its original shape, I must say that this side of the bone much more reminds me of a coracoid, such as that in the drawing below, with the bone being much thinner on opposite sides of the tubercle running the horizontal length of the bone and connecting to the area you previously identified, on the obverse, as the "dorsal process" (please note that exactly this area is also visible as a gap between the two coracoids below).

 

Dorsal view of the pectoral girdle of Trinacromerum. Figure 102 from Williston, 1925. The Osteology of the Reptiles

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Now, I realise that Trinacromerum was a Late Cretaceous polycotylid from North America, and may as such may not appear immediately applicable as an analogue here. However, the below photographs of the Liopleurodon ferox specimen at the Paläontologische Sammlung of the MUT Tübingen illustrates that British Oxfordian pliosaurs from the also had them, and that they are, in fact, rather prominent.

 

 

In fact, this appears to be an ancestral trait, with even such early species as the Sthenarosaurus, a rhomealosaurid pliosaur, of which the below two photographs illustrate a specimen found in the Pliensbachian of Nancy, also from the collections in Tübingen.

 

 

 

The nature of the tubercle seems to be congeneric, however, as the tubercle of Peloneustes philarchus appears way less robust than that of L. ferox. As such, If I'm correct in my assumptions on your fossil being that of a pliosaur coracoid, then it may well be of L. ferox.

 

Peloneustes philarchus specimens in the Paläontologische Sammlung of the MUT Tübingen (l) and Naturmuseum Senckenberg in Frankfurt (r)

 

 

 

 

 

 

 

 

 

I see what you mean about the similarity to a coracoid. I don't see a ridge leading backwards from the articulation on any of these coracoids though. It was the distinctive ridge that made me think Scapula in the first place (the so called ventral ridge). A friend has a Kimmeridgian giant pliosaur scapula in his collection (this is confimed as a scapula by Steve Etches this am as he has the other one from the same individual). The overall form of this bone seems very similar to one we are discussing, although it is considerably smaller. See if you think it matches mine:

 

 

 

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Something else that may be of interest in this context is the below fragments of bone found in the Kimmeridgian of the Boulonnais (France) by a friend of mine, originally from a single bone but broken on extraction. To my mind there are various similarities here to your bone, if only the "dorsal process". He had it put down as a pelvic bone. But during our communications, the possibility of the specimen being a coracoid was also raised - although the bone's fragmentary nature left the exact origin of the specimen unclear in the end...

 

 

To me that does look more like a coracoid. The edges are quite thin, whereas the 'dorsal process' on my and the Kimmerigian scapula is very robust. How big is it? Steve Etches asked who the collector is, as he has been over to that area and met some of the collectors.

 

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I hope this helps!

Cheers,
Alexander.

 

Thank you for all your input on this. I very much appreciate it. Maybe one day we will solve this mystery. Let me know your further thoughts please.

 

Paul

 

P.S. this is an attempt I made to match the bone against the type specimens of L. ferox and S. vorax:

 

 

 

[DE&i]

I'm going with Pliosaur for both vertebra.