Aust Cliff (Rhaetian Triassic UK) bone ID

[JoeM]

I managed another trip to Aust and as I had a better idea what I was looking for managed to get a few bits of bone bed to sift through back home -  one of whch was this nicely preserved piece of what I presume is reptile bone (approx 6cm long?) 

 

My guess is a partial rib (although it is completely flat, with no visible curvature), in which case given size and location most probably Pachystropheus, but I'd love to get any more thoughts. 

 

 

[Notidanodon]

nice find, from the size, i think Pachystropheus is more likely but im not sure there's any diagnostic features

[pachy-pleuro-whatnot-odon]

@Welsh Wizard might be able to help out here. But, yeah, it does look like a good candidate for a Pachystropheus rhaeticus rib section. I don't have too much except for vertebrae to compare against, though...

[JoeM]

Thanks so much for the replies! Is there any way it could be a small ichthyosaur rib? Looking at pachystropheus ribs they all seem to be curved whereas this is very straight.

[JoeM]

Also whilst I’m here and I know I have experts to hand, I initially thought it might be a fin spine but is this a plesiosaur tooth with pieces of root? It’s approx 4cm long.

[pachy-pleuro-whatnot-odon]

45 minutes ago, JoeM said:

Also whilst I’m here and I know I have experts to hand, I initially thought it might be a fin spine but is this a plesiosaur tooth with pieces of root? It’s approx 4cm long.

 

We'll need better photographs, more close-up shots, to be able to determine that. From what I'm seeing right now, I wouldn't say so, because I'm not seeing any enamel...

 

54 minutes ago, JoeM said:

Thanks so much for the replies! Is there any way it could be a small ichthyosaur rib? Looking at pachystropheus ribs they all seem to be curved whereas this is very straight.

 

While possible, I wouldn't think so, since ichthyosaur ribs have a very diagnostic thinning in the middle part of the rib, generally being more flat-like than rounded.

[Welsh Wizard]

Hi

 

It looks like a tooth at first glance but the teeth tend to be black rather than brown. It’s probably a fun spine piece.

 

The rib piece could be from anything. It’s always helpful to look at the cross section of ribs as that can help you work out what it is. 
 

Nice finds. Great place Aust but can be very hit and miss. It’s also really hard to ID material from photos due to the variety of bones teeth inclusions and coprolite as you get together.

[JoeM]

5 hours ago, Welsh Wizard said:

Hi

 

It looks like a tooth at first glance but the teeth tend to be black rather than brown. It’s probably a fun spine piece.

 

The rib piece could be from anything. It’s always helpful to look at the cross section of ribs as that can help you work out what it is. 
 

Nice finds. Great place Aust but can be very hit and miss. It’s also really hard to ID material from photos due to the variety of bones teeth inclusions and coprolite as you get together.

Thanks all, really useful replies. I think it was slightly delirious late night wishful thinking striking again, upon looking at plesiosaur teeth from there they are all dark in colour so it is clearly not. Still happy with a nice little hybodont spine though! Seems like the other one is likely Pachystropheus then. I'm just a bit confused as it is so flat and perfectly straight, as to what bone it could possibly be (as looking at pachystropheus ribs they are curved. I guess sadly I may simply never know  Again, a nice little piece nonetheless. 

 

I am gradually working my way through some other pieces trying to to make some sense of them. One that did intrigue me was this thin cross section of bone - obviously most of the bone fragments are unidentifiable beyond marine reptile of some kind but the shape of this with the hole and outline was distinctive enough that I hoped I might at least be able to narrow it down a bit more than that...

approx 10cm high.

 

 

 

 

Edited April 5, 2023 by JoeM
additional info

[JoeM]

Could it be a cross section of neural arch? if so is it identifiable to group, eg plesiosaur? 

[pachy-pleuro-whatnot-odon]

38 minutes ago, JoeM said:

Could it be a cross section of neural arch? if so is it identifiable to group, eg plesiosaur? 

 

I like the suggestion, was a bit puzzle about it myself... If indeed a neural arch, then I'd definitely say plesiosaur, as none of the other large marine vertebrates from those deposits would have such fused neural arches.

[JoeM]

Interesting. Is there anything I could do that would help an ID of neural arch (or otherwise)? I'm tempted to try and prep a bit more of it out but I keep falling foul of trying to do too much excavation with these. I'm not sure there are any other bones that have a hole through them like that are there? I need a good comprehensive anatomical text.

[JoeM]

Could it potentially be something along the lines of that in Fig A or C here (plesiosaur caudal vertebrae)? I realise definitive ID is probably a tall order here but if I feel fairly confident that it's pretty likely that'd be enough to keep me happy for now  If so, I wonder if there is any method of crudely estimating size range possibilities. I'm imagining the owner of such a neural arch would be quite large. 

[pachy-pleuro-whatnot-odon]

17 minutes ago, JoeM said:

Interesting. Is there anything I could do that would help an ID of neural arch (or otherwise)? I'm tempted to try and prep a bit more of it out but I keep falling foul of trying to do too much excavation with these. I'm not sure there are any other bones that have a hole through them like that are there? I need a good comprehensive anatomical text.

 

13 minutes ago, JoeM said:

Could it potentially be something along the lines of that in Fig A or C here (plesiosaur caudal vertebrae)? I realise definitive ID is probably a tall order here but if I feel fairly confident that it's pretty likely that'd be enough to keep me happy for now  If so, I wonder if there is any method of crudely estimating size range possibilities. I'm imagining the owner of such a neural arch would be quite large.

 

To be fair, one of the main things that keeps me from fully being confident about this being neutral arch is that the spinous process seems rather thick for that... Even in supersized marine reptiles it wouldn't get as thick.

 

Which brings back the question of what this could be, if not a neural arch. Wood is always a possibility, and quite often contains bore holes - which could still be possible with bone as well, I believe, albeit a lot less common - but the texture here looks more like bone than wood to me. This leaves the possibility of a skull bone. But with such a fragmentary section, it'll all be hard to say...

[JoeM]

Thanks, yes sounds like I could have been a bit optimistic hoping for a more specific ID on this then. There is still some hidden away to be exposed so may get the paraloid on it and see if I can shed any more light.

[JoeM]

@Welsh Wizard @pachy-pleuro-whatnot-odon I hope nobody minds but I may gradually post up bits on this thread as I work my way through them. I have another bone piece I have some hope may be able to be identified beyond 'chunk' - a cross section of what I suspect to be a vertebra centrum - though not sure if ichthyosaur or plesiosaur would be the prime candidate as still learning (again, may simply be unidentifiable!).  I'm going to try and remove a bit more matrix as although partial what is there seems to be quite nicely preserved. It also needs to be glued back together. Interested if my hunch seems likely. It's about 3cm across. It has a process coming from one side that seems to have a channel running through it (for nerves?)

 

Edited April 6, 2023 by JoeM
removed blurry image

[JoeM]

Also have what I suspect could be a fish jaw / skull bone of some kind. It has the flaky texture I think from my limited knowledge is indicative of fish bone and is fragile, I am hoping to spend a bit of time seeing what I can do to prep it. It has come out in two lateral slices at the moment - here's the left and right matching sides:

[JoeM]

And here is a top view of the left piece (currently in two parts)

[JoeM]

If you look at the lower part you can see it gets a lot wider at that end - another view

[JoeM]

and on the other side of the wide end there are lots of fragments that look like they could be associated (but also could well not be!)

 

[JoeM]

Here's a magnified view to show the texture - am I right in thinking this flaky texture is fish bone?

[JoeM]

And finally a close up of some of the debris that is covering the wide end. Quite an interesting piece all in all.

[pachy-pleuro-whatnot-odon]

Really tricky material to identify... For the second piece, people do indeed say that a flaky bone texture is indicative of fish. But I, myself, lack the experience to either confirm, deny or apply this knowledge. Also, I'm having quite a bit of difficulty seeing any recognizable shape in the second specimen. Could this potentially be a bit of wood? Although, I don't think any fossil wood is found at Aust Cliff, so fish would, in that case, indeed be a more reasonable assumption.

 

As for the potential vertebra: the way to tell plesiosaur and ichthyosaur apart in cross-section is that ichthyosaur vertebrae invariably have an hourglass-shaped cross-section. I'm not seeing this here. And while I, again, find it difficult to form a good impression of your find, it seems more likely to be a plesiosaur rather than ichthyosaur vertebra, simply because of the more rectangular shape of the cross-section.

[JoeM]

Thanks for the reply as always! Yes these are going to be hard to id at the best of times and these photos don’t make it any easier. It is hard to get the same impression as you can in person in three dimensions especially when they are fragmentary and need work. I am however reasonably confident that the potential vertebra is one as in person it is a nice level of preservation but hopefully removing remaining matrix will help confirm. As for the second piece - it looks quite convincingly (to me at least!) like a single slightly crushed piece of bone with quite a distinctive shape in person but hopefully more work will help elucidate that. If it is def fish bone (it did cross my mind too that wood was possible as not very experienced) then I guess I figured a skull bone of some form was the only likely candidate given the shape and size. Would be good to hear from someone fishy focused on that particular issue then I guess. Well I’m going to keep working on all these and see if I can get any closer to some outcomes! Either way even if I can’t confirm IDs they are all interesting pieces

[JoeM]

@pachy-pleuro-whatnot-odon do t know if this makes it a bit easier to see what is going on (possibly not!) but here’s another shot of the partial ‘vert’ from the upper surface also showing an oblique view of the inner bone cross section. You are correct in observing that it only has a pronounced dip towards the centre on the upper surface.

[JoeM]

@pachy-pleuro-whatnot-odon sorry to keep copying you in (and feel free to ignore  ) but I’ve had a go at prepping the possible plesiosaur vert and taken some better pics so was interested as to whether this might help get closer to an ID (or whether I’m on to a lost cause - if so it’s still a nice looking little piece I’m happy  with  )…