Unidentified Triassic reptile bone

[pachy-pleuro-whatnot-odon]

On 12/16/2020 at 2:21 PM, Mahnmut said:

On 12/16/2020 at 1:48 AM, pachy-pleuro-whatnot-odon said:

 

 

Rhomaleosaurus victor cast at the Zoological and Palaeontological Collections of the University of Zürich

 

 

 

 

 

 

 

 

 

 

 

In other depictions of plesiosaur pelves Ischium, pubis and even coracoids seemed strangely similar, but looking at the Rhomaleosaurus, the ischium seems to be a  better fit than the pubis in my eyes.  So Ischium , maybe pubis, of a smallish animal not to far from plesiosauria?

To me it can only be a pubis. For if my bone matches the pubis in all other examples of plesiosaurs (and even plenty of other sauropterygians), then it would be strange for a single species to break this pattern, right? I do see how you get to the visual comparison, though, if you rotate R. victor's ischium 90 degrees counter-clockwise. But in that case, you'd need to ignore the bend in the "process" (for lack of a better word) in my bone, or at the very least ignore the direction the break in my bone seems to extend the bone in. For me this can therefore not be a plesiosaurian ischium - or a nothosaurian, for that matter (see images above) - since the process that projects from the fanning part of that bone always stands at right angles to the fan.

 

[pachy-pleuro-whatnot-odon]

On 12/16/2020 at 12:48 PM, Pemphix said:

The piece is coming from the Anthrakonitbank in Kirchberg which is Middle Triassic, Ladin, Longobard, lower Keuper (Lettenkeuper), Erfurt-Formation, ku2.

The only known placodont from the Anthrakonitbank is Psephosaurus suevicus, which is very rare and known only by some armor-plates and teeth. I don't think, that your piece belonging to this placodont.

Concerning Ichthyosaurs: the only known and valid species in Germany from the middle triassic are (according to MAISCH&MATZKE 2000: The Ichthyosauria): Contectopalatus, Phalarodon, Phantomosaurus and Cymbospondylus. None of them are known in the Lower Keuper - they are pretty rare in the Lower and upper Muschelkalk below, too. 

Since the Anthrakonitbank is a immature Bonebed with a strong (shallow) marine fauna, high-marine fauna is not to be expected.

No plesiosaurs known from this horizon, the first (and only one till now) is from much more younger rhaetian of age (upper keuper, boundary to lowermost jurassic; Westphaliasaurus simonsei).

Pretty often are Sauropterygian remains, namely those from Nothosaurs, most often specis is N. edingerae. So my best guess would be a sauropterygian remain (most likely nothosaurid).

Wow! That's exactly the expertise I was looking for! So much information! Thank you, @Pemphix!

 

So, it turns out we are in the latest stage of the Triassic after all. That changes quite a bit then, I'd say, as I've disregarded some genera from my own analysis based on their temporal constraints. As you can see from my last posts above, I also started hesitating about the bone being placodont. So it's good to know that, based on what's know from the deposits at the find location, this can be excluded to a high degree of likelihood (i.e., de facto completely). And though I don't agree that ichthyosaur could be ruled out because the four genera known only occur prior to the Keuper - for the simple reason that absence of evidence is not the same as evidence of absence - if these animals were around before, they may still have been present after, especially if they were rare finds to begin with (same for plesiosaurs: they must've come from somewhere) - I do think we can rule them out due to two of them being mixosaurids and the other two being cymbospondylids, both clades that, as set out above, do not have coracoid or pubis bones matching my specimen.

 

Although I have no idea what an "immature bonebed" is, I think it's also significant you write that the deposit from which the bone derives is a shallow marine one. This would indeed seem to exclude the bigger ocean-going species like ichthyosaurs and plesiosaurs - even if these species could, of course, have looked for shallower nursery areas, much like sharks do. However, I'm not aware of any studies on the topic, and it doesn't seem unreasonable to assume that these viviparous reptiles would have just given birth in open waters. A nothosaurid therefore does not seem like such a stretch.

 

On 12/16/2020 at 2:21 PM, Mahnmut said:

On 12/16/2020 at 1:48 AM, pachy-pleuro-whatnot-odon said:

So Ischium , maybe pubis, of a smallish animal not to far from plesiosauria?

Such as a nothosaurid, may be?

 

Yet, if I look at below diagram and image, I find little in terms of comparison between nothosaurid pubes and my bone. Rather, there seems to be more visual similarity with other sauropterygians...

 

From Diedrich, 2003. Ein bemerkenswerter Reptil-Pubisfund ausdem Oberen Wellenkalk (Unterer Muschelkalk) von Niederlistingen, Nordhessen

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nothosaurus mirabilis pubis, from Fossilien aus dem Muschelkalk des Kraichgaus (note the presence of a notch and projection next to it)

 

 

 

 

 

 

 

 

 

 

As said, I also don't believe this to be an ischium, of which below image illustrates a sample:

 

Figure 1 from Lankamp, 2002. Bijtsporen op een sauriërbot uit Winterswijk

 

 

 

 

 

 

 

 

 

 

 

Looking at a cladogram for nothosaurids, however, it seems that the proposed Nothosaurus edingerae is rather a basal member, and thus presumable has a pubis intermediate between types F and H in the diagram above:

Figure 5 from Lin, Jiang, Rieppel, Motani, Ji, Tintori, Sun & Zhou, 2017. A new specimen of Lariosaurus xingyiensis (Reptilia, Sauropterygia) from the Ladinian (Middle Triassic) Zhuganpo Member, Falang Formation, Guizhou, China

 

 

 

 

 

 

 

 

 

 

Unfortunately, though, I did not record the identity of the nothosaurid I photographed at the Paläontologische Sammlung of the MUT in Tübingen, and haven't been able to find a corresponding image record in their collection on WikiMedia to correlate it to. But this still seems like one of the best matches, especially if going for nothosaurid:

 

 

Alternatively, below is an attempt to reconstruct the pubis based on F-H from Deidrich's (2003) figure 4, with a potential reconstruction at the bottom right. Note that I've rotated each of the sample pubis bones in the same way. This is because each of the drawings shows a foramen in the lower right corner (the obturator-foramen), which I suspect to have also been present on my bone, in the lower right-hand corner. Currently it looks like some repair may have been performed in that area, and my suposition is that this repair was made to cover up what the preparator thought to be a gap or break in the bone, but was actually the pubis' obturator-foramen. As can be seen, none of the samples is a perfect match by far. But may be it's close enought to just classify it as "Nothosaurus sp. pubis" or "Indet. sauropterygia pubis" (which is my current label for the bone).

 

 

I think I'll leave it at that. Thank you all so much for your help!

 

 

 

[Mahnmut]

Excuse the crude graphic, I am still not as used to gimp as I was to photoshop.

The siluette I used is F from above( Diedrich, 2003), Simosaurus. I do see that it is no exact match, what does fit well is the shape of the  upper notch if oriented like below.

I dont claim to have any knowledge here, just looking at shapes.

Best Regards,

J

[Pemphix]

On 18.12.2020 at 6:28 PM, pachy-pleuro-whatnot-odon said:

So, it turns out we are in the latest stage of the Triassic after all.

No. As i wrote it is Middle Triassic, Ladin, Longobard, lower Keuper (Lettenkeuper), Erfurt-Formation, ku2.

 

On 18.12.2020 at 6:28 PM, pachy-pleuro-whatnot-odon said:

And though I don't agree that ichthyosaur could be ruled out because the four genera known only occur prior to the Keuper - for the simple reason that absence of evidence is not the same as evidence of absence - if these animals were around before, they may still have been present after, especially if they were rare finds to begin with (same for plesiosaurs: they must've come from somewhere).

Since i 've collected this strata intensively for more than 30 years (and many other scientist and collectors, too), it is more than unlikely, that someone would have overseen ichthyosaurs and plesiosaurs if present. You may have a look in the corresponding articles and publications.

 

On 18.12.2020 at 6:28 PM, pachy-pleuro-whatnot-odon said:

Although I have no idea what an "immature bonebed" is, I think it's also significant you write that the deposit from which the bone derives is a shallow marine one. This would indeed seem to exclude the bigger ocean-going species like ichthyosaurs and plesiosaurs - even if these species could, of course, have looked for shallower nursery areas, much like sharks do. However, I'm not aware of any studies on the topic, and it doesn't seem unreasonable to assume that these viviparous reptiles would have just given birth in open waters. A nothosaurid therefore does not seem like such a stretch.

 

 

The deposit we are talking about is a erosional horizon (bonebed) which therefore consists of a lot of different species, those Bonebeds can have several states of "mature": see REIFF & HAGDORN for details.

 

As said, no plesiosaurs known from this locality and in this part of the Keuper throughout middle europe - they are occuring in the fossil record of middle europe first time in the last triassic layers under the jurassic boundary. It is very unlikely to find them in the Anthrakonitbank as well as Ichthyosaurs.  

 

On 18.12.2020 at 6:28 PM, pachy-pleuro-whatnot-odon said:

Looking at a cladogram for nothosaurids, however, it seems that the proposed Nothosaurus edingerae is rather a basal member, and thus presumable has a pubis intermediate between types F and H in the diagram above.

 

It is the very last Nothosaur in the Keuper of mid-european. 

 

On 18.12.2020 at 6:28 PM, pachy-pleuro-whatnot-odon said:

But maybe it's close enought to just classify it as "Nothosaurus sp. pubis" or "Indet. sauropterygia pubis" (which is my current label for the bone).

I think I'll leave it at that. Thank you all so much for your help!

 

Would be a good first approach i think. Do not forget, that the shape of the bone do not necessarely reflects the true shape: due to heavy erosion and re-deposition they can be deformed and degraded in many ways...

 

[pachy-pleuro-whatnot-odon]

1 hour ago, Pemphix said:

No. As i wrote it is Middle Triassic, Ladin, Longobard, lower Keuper (Lettenkeuper), Erfurt-Formation, ku2.

Sorry, that was a typo on my end - don't know how it slipped in there. As I was thinking about ichthyosaurs, I had meant to write "latest stage of the Middle Triassic".

 

1 hour ago, Pemphix said:

Since i 've collected this strata intensively for more than 30 years (and many other scientist and collectors, too), it is more than unlikely, that someone would have overseen ichthyosaurs and plesiosaurs if present. You may have a look in the corresponding articles and publications.

Okay, I wasn't aware of that. I mean, if you personally know the site (rather than from literature) and have extensively collection from it, and the locality has moreover seen intensive scrutiny by palaeontologists, this certainly reduces the chances of something new showing up now. Though I had already dismissed ichhyosaur as candidate for my bone, I just did not feel like dismissing them entirely, as I know for a fact that they are found across the border in France, in what must be similarly ages strata. Anyway, no ichthyosaurs or plesiosaurs then...

 

Would you be able to recommend a small (with emphasis on small) number of articles most pertinent to the Kirchberg quarry, that would furnish me with a background on the locality. I'm not a fast reader, and the fact that I had a couple of hundred articles still lined up to have a glance at if I'd ever find a time away from family to read is kind of indicative of how little of an opportunity I get...

 

1 hour ago, Pemphix said:

The deposit we are talking about is a erosional horizon (bonebed) which therefore consists of a lot of different species, those Bonebeds can have several states of "mature": see REIFF & HAGDORN for details.

Would this be Hagdorn & Reiff, 1988? I've just looked for it online and found it referenced. But with the publication being so old, I doubt I can easily find it as an online resource. As I don't have a subscription or other access to any academic portal, it might take a while to chase this down. What I did find, however, if the below illustration (figure 25) from Boessenecker, Perry and Schnmitt (2014. Comparative Taphonomy, Taphofacies, and Bonebeds of the Mio-Pliocene Purisima Formation, Central California: Strong Physical Control on Marine Vertebrate Preservation in Shallow Marine Settings):

 

 

Presuming that the situation in Middle Triassic Germany/Central Europe doesn't differ from that Neogene of California, may I assume that a "mature bonebed" equates to condition A in the diagram, and the situation at Kirchberg (i.e. "immature bonebed") refer to conditions B1 and B2?

 

1 hour ago, Pemphix said:

On 12/18/2020 at 6:28 PM, pachy-pleuro-whatnot-odon said:

Looking at a cladogram for nothosaurids, however, it seems that the proposed Nothosaurus edingerae is rather a basal member, and thus presumable has a pubis intermediate between types F and H in the diagram above.

 

It is the very last Nothosaur in the Keuper of mid-european. 

Does this mean the branches in the cladogram are incorrect, or rather that the branching in the diagram doesn't follow the progression of speciation through time, as might be expected. That is, I know that cladistics don't need to follow the temporal progression of speciation through time - and this is, indeed, frequently not the case - but, intuitively, one would say that a more derived genus would occur later in time than a more basal one and, thus, that the more derived genus would not originate from a genus multiple steps removed from it in time...

 

Are there any online resources (freely) available that discuss or exhibit N. edingerae?

1 hour ago, Pemphix said:

Would be a good first approach i think. Do not forget, that the shape of the bone do not necessarely reflects the true shape: due to heavy erosion and re-deposition they can be deformed and degraded in many ways...

I'm aware of plastic deformation, yes. That's also the reason I didn't mind the overlays in my reconstruction attempt not exactly matching... Still, I consider the notch so notably different from the slight bend in the bone found on other nothosaurid pubes that it makes me wonder about classifying the bone as nothosauria. I hadn't considered @Mahnmut's projection yet, though, so I've give that a try when I've got time and see where it gets me.

 

Again: thanks for all the help and information. It's very much appreciated!

[Pemphix]

On 20.12.2020 at 4:03 PM, pachy-pleuro-whatnot-odon said:

Would you be able to recommend a small (with emphasis on small) number of articles most pertinent to the Kirchberg quarry, that would furnish me with a background on the locality. I'm not a fast reader, and the fact that I had a couple of hundred articles still lined up to have a glance at if I'd ever find a time away from family to read is kind of indicative of how little of an opportunity I get...

 

Would this be Hagdorn & Reiff, 1988? I've just looked for it online and found it referenced. But with the publication being so old, I doubt I can easily find it as an online resource. As I don't have a subscription or other access to any academic portal, it might take a while to chase this down.

 

 

https://www.researchgate.net/publication/285013920_Die_Knochenbreccie_von_Crailsheim_und_weitere_Mitteltrias-Bonebeds_in_Nordost-Wurttemberg_-_Alte_und_neue_Deutungen

http://www.palaeodiversity.org/pdf/08Suppl/14Palaeodiversity_SB_Hagdorn.pdf

https://link.springer.com/chapter/10.1007%2F978-3-642-75829-4_22

 

On 20.12.2020 at 4:03 PM, pachy-pleuro-whatnot-odon said:

Presuming that the situation in Middle Triassic Germany/Central Europe doesn't differ from that Neogene of California, may I assume that a "mature bonebed" equates to condition A in the diagram, and the situation at Kirchberg (i.e. "immature bonebed") refer to conditions B1 and B2?

 

Pls. refer to the literature above (and to the links for further detailed literature).

 

On 20.12.2020 at 4:03 PM, pachy-pleuro-whatnot-odon said:

Does this mean the branches in the cladogram are incorrect, or rather that the branching in the diagram doesn't follow the progression of speciation through time, as might be expected. That is, I know that cladistics don't need to follow the temporal progression of speciation through time - and this is, indeed, frequently not the case - but, intuitively, one would say that a more derived genus would occur later in time than a more basal one and, thus, that the more derived genus would not originate from a genus multiple steps removed from it in time...

My point was that N.edingerae is the last Nothosaurid in the mid-european triassic sediments, there are no more finds of Nothos after the Gipskeuper (which reaches in Baden-Württemberg from the border Ladin/Karn to lower Karn (lower part of the middler Keuper; 235-332 m.y.). 

 

On 20.12.2020 at 4:03 PM, pachy-pleuro-whatnot-odon said:

Are there any online resources (freely) available that discuss or exhibit N. edingerae?

https://www.biodiversitylibrary.org/item/20523#page/3/mode/1up

https://archive.org/stream/stuttgarterbeitr2012191994staa#page/n75/mode/2up

http://www.terra-triassica.de/museum-terra-triassica/sammlung-und-werkstatt/makrofossilien/vertebrata-lamarck-1794/reptilia-linne-1758/nothosaurus-muenster-1834/nothosaurus-edingerae-schultze-1970/

 

[pachy-pleuro-whatnot-odon]

Wow! Thanks for all the information, @Pemphix! Had a quick scan through them, and these look like great articles, exactly of the type I like to read! This will keep me occupied for a while still

[pachy-pleuro-whatnot-odon]

On 12/18/2020 at 7:01 PM, Mahnmut said:

Excuse the crude graphic, I am still not as used to gimp as I was to photoshop.

The siluette I used is F from above( Diedrich, 2003), Simosaurus. I do see that it is no exact match, what does fit well is the shape of the  upper notch if oriented like below.

I dont claim to have any knowledge here, just looking at shapes.

Best Regards,

J

Sorry for taking a bit long to respond to this, I had to find a bit of consecutive opportune moment to work on it. But since I liked your suggestion, I decided to try it out visually, see if it works out as well as it would appear to do. See below what I came up with:

 

 

First off, note that I decided to rotate the pubis bones just a slight bit more than in your edit, owing to the notch between the two major (top) parts of the bone then forming a more exact match. The second thing to note is that, seen in this position, only the Simosaurus gaillardoti pubis seems to be a viable option, as the other pubis bones are too straight on their right side to account for the curve at the bottom of my bone. Even so, in order to respect those areas where my bone was unbroken, and the curvature indicated by it, I was forced to tilt the bottom part of the "Simosaurus morphotype" pubis back in the opposite direction. This kind of leads to an odd relative configuration of the two top extremities of my bone, but generally seems to result in a rather nice and acceptable option, I think. I'm just not sure whether this is because it was just easier to manipulate the layout of the bone from this position, where half of the bone can be shifted around freely (versus my own earlier attempt) or whether this is purely because of the better fit provided. There does, however, seem to be less plastic deformation needed to arrive at this version then there would be in my earlier attempt (i.e., the degree in which the shapes of the bone can be made to match), even if the bone ends up being larger than the one illustrated by Diedrich (2003) (could the presumed deformation in my specimen therefore simply be the outcome of a difference between an immature and mature animal, or perhaps different subspecies?).

 

Another point that confuses me a bit is that if I take Pemphix's suggestion of the bone likely belonging to N. edingerae (which I still need to read up on further), this would be one of the last and, therefore presumably most derived, species of nothosaur, whereas Simosaurus is an early, and therefore more basal species. Or is the above cladogram correct in N. edingerae not having evolved to much beyond the Simosaurus basal condition (following that cladogram, for instance, N. marchicus and Simosaurus are a lot further apart then are the latter and N. edingerae).

 

Regardless of this exercise, I think I'll maintain my former identification of "indet. sauropterygia pubis". All the same, thanks for the help! I now at least think that the "indet. sauropterygia" is, in fact, likely to be "Nothosaurus sp."!