Somewhat fishy

[Mahnmut]

I really have no good idea how the limbs where coming out of the carapace in Henodus.

The skull will be 3dprinted again, as with placodus I  am digitally sculpting it myself.

Other than that, I consider this one complete.

Aloha,

J

[Mahnmut]

Well, its a strange looking creature, and the skull won´t change that.

[Dinoguy89]

Really love these, I can tell you put in the work. They look great, congrats

[Mahnmut]

Thanks Dinoguy!

[Fossildude19]

It is a treat to see you complete these wonderful models!  

[Tidgy's Dad]

How marvelous.

Proper works of art. 

[Mahnmut]

Thanks Fossildud and Tidgys Dad! I am really glad you like my critters.

I just thought I should have taken more pictures of the early stages.

Cyamodus is next, I will keep you up to date.

 

Aloha,

J

[Mahnmut]

Nearly done.

This one was easy, using the Placodus skull as a basis. When the jaw is ready it can go to the printer together with Henodus´ skull.

Postcranial will be handmade again. Those carapaces are a lot more fun to make than simple ribs.

Cheers,

J

[Mahnmut]

Next steps.

[Mahnmut]

paper on fimo on aluminum foil, as with Henodus.

[Mahnmut]

Postcranial nearly done, skulls for Henodus and Cyamodus are on the way to the printer.

Aloha

J

[Mahnmut]

3d printed skulls arrived today.

[Mahnmut]

Family foto.

 

[pachy-pleuro-whatnot-odon]

Impressive! Wish I'd be skilled enough to put something like this together...! 

[Mahnmut]

Thank you @pachy-pleuro-whatnot-odon!

 

After a long break, here comes another marine reptile, Hupehsuchus:

Hitherto using Blender predominantly to distort recent skeleton scans into fossil relatives, after some hints from @thorst I now try to build a Skeleton from scratch.

Completely digital for now, and not complete yet. Missing references for the shoulder and pelvic girdle. If I succeed in making it printable, Eretmorhipis will be next, then maybe a Liopleurodon? Somewhere in between I should get started with my master thesis though, so the schedule is open to changes.

Aloha,

J

 

 

[pachy-pleuro-whatnot-odon]

That's starting to take shape nicely, @Mahnmut! And definitely am in favour of the Liopleurodon on your "planned models"-list

[thorst]

Looks great, and I am in awe of the speed you make progress with blender! Unfortunately I cannot help you regarding references for Hupehsuchus, but if you need references about Liopleurodon in the future let us talk again...

 

Good luck with the thesis!

 

Cheers,

Thorsten

[Mahnmut]

On 19.1.2021 at 9:19 PM, thorst said:

 the speed you make progress with blender! [...]Good luck with the thesis!

Behold the power of procrastination!

 

Thanks to both of you.

@pachy-pleuro-whatnot-odon, when I proceed with my pectoral girdle, maybe you can tell me if it is at least plausible for something supposedly related to Ichthyopterigia. Liopleurodon wil be easy after that, I think.

Aloha,

J

[pachy-pleuro-whatnot-odon]

14 hours ago, Mahnmut said:

Behold the power of procrastination!

Yeah, if I think back to the amount of time I had as a student... Those were real times of luxury!

 

14 hours ago, Mahnmut said:

Thanks to both of you.

@pachy-pleuro-whatnot-odon, when I proceed with my pectoral girdle, maybe you can tell me if it is at least plausible for something supposedly related to Ichthyopterigia. Liopleurodon wil be easy after that, I think.

Aloha,

J

Concerning the paddle, first of all, I think this looks very plausible: humerus and femur bones seem to have obtained their typical flat, rectangular shape very early on in ichthyopterygian evolution, while the lower arm and leg bones - though also already having become flattened - still retain their elongate long-bone shape (a sequence of morphological changes that can be observed in mosasaurids too, by the way). See below images for reference:

 

Figure 4 from Motani, 2005. Evolution of fish-shaped reptiles (Reptilia: Ichthyopterygia) in their physical environments and constraints

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hind-paddles of a mixosaurid from China.

 

 

 

 

 

 

 

 

 

 

 

As to the other pectoral girdle elements, this will be a bit harder for the very fact that - as you're undoubtedly aware - a lot of specimens from this time have been preserved in a flattened, if not crushed, state. I'd therefore suggest first taking a look at the way these elements are supposed to be configured using a three-dimensionally better preserved specimen of a later ichthyosaur, such as the Ophthalmosaurus icenicus from the Paläontologische Sammlung, MUT Tübingen below:

 

sa = scapula; co = coracoid; cl = clavicula; icl = intercalvicular

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

With this idealised configuration in mind, we can now look at the shapes the involved bones take in early ichthyopterygians:

 

Pectoral girdle of Cymbospondylus sp. at the Zoological and Palaeontological Collections of the University of Zürich

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mixosaurus sp. front paddle and pectoral girdle (l) and cast of the front part of Besanosaurus leptorhynchus (r) at the Museo Civico dei Fossili di Besano in Besano.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This can also be represented schematically as below:

 

From: McGowan & Motani, 2003. Ichthyopterygia

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jiang, Schmitz, Hao and Sun, 2006. A new mixosaurid ichthyosaur from the Middle Triassic of China

 

 

 

 

 

 

 

 

 

As you can see, the shape of the claviculae and interclavicular have changed very little over time and, as such, very closely match you model. The shape of scapulae and coracoids range from semi-lunate to fan-shaped, with the fan-shape probably being more ancestral, seeing as it occurs in so many other animal species. Thus, when you add the scapulae to your model, I'd use fan-shaped ones, with the fans pointing backwards from the humeri, their largest projection directed ventrally.

 

Determination of the proper shape for the coracoids seems a bit more difficult to me, as I'm less familiar with the bone in general, and there seems to be more variation amongst animal species. However, when comparing the coracoids of early ichthyopterygians in McGowan & Motani (2003), almost all of them are semi-lunate, even that of Mixosaurus spp. to the extent illustrated above. Even though the latter does appear somewhat more fan-shaped, this seems to be specific to the genus, as it's neither the earliest nor the latest early ichthypterygian I'm comparing data from here (according to McGowan & Motani [ibid.] this would be Besanosaurus, Mixosaurus, Cymbospondylus and Shastasaurus). As such, I would go for a semi-lunate to rectangular shape, which appears to be what the bigger ichthyopterygians seem to have. Optionally, you could add a rounded articulation, similar to Mixosaurus', to one end, as it seems likely this would be an ancestral feature lost in larger and later ichthyopterygians.

 

Then comes the matter of positioning. Again, the coracoids present more of a problem, as they are frequently not as clearly visible amongst the flattened skeletal ichthyosaurian remains - nor are they in those specimens mounted in three dimensions, for that matter. That their articular surfaces would connect to the humuri as the scapulae do, and they would, from there, project medially to the skeleton seems a given, as does the fact that they lie in the extension of the curved plane containing the gastralia. However, as to what direction the semi-lunate part of the coracoid would be pointed towards, I've only been able to find the below image as a reference for (see the lighter-coloured specimen). From that, it seems that the convex part goes posteriorly, the concave one anteriorly.

 

Temnodontosaurus trigonodon in the Naturkundemuseum Stuttgart

 

 

 

 

 

 

 

 

 

 

 

I hope this helps.

 

Alexander

[Mahnmut]

Thanks Alexander,

 

I think I have now something like a plausible pectoral and pelvic girdle for Hupehsuchus. I am not sure if the scapulae should be there though.

Best regards, J

[pachy-pleuro-whatnot-odon]

6 hours ago, Mahnmut said:

Thanks Alexander,

 

I think I have now something like a plausible pectoral and pelvic girdle for Hupehsuchus. I am not sure if the scapulae should be there though.

Best regards, J

No worries, glad to help! There's a couple of things that don't feel quite right about this model to me yet, though. The first is that, as pointed out above, the scapula, and may be the coracoid too, appear way too derived, and out of place, for such an early ichthyopterygian. I would've therefore opted for the more fan-shaped scapula, but also moved the whole pectoral girdle a bit lower, so that the line and angle of the gastralia would be extended into the coracoid and clavicula. Not only does this give the Hupehsuchus more mobility by not having its arms on top of its stomach, but it actually naturally extends the barrel-shaped body-plan instead of constricting it, as is the case in the current configuration. Have a look at the below skeletons of Ophthalmosaurus incenicus from the Natural History Museum in London and reconstructed Hupehsuchus nanchangensis (though this comes from Reptile Evolution, I think it's a reasonable enough interpretation to illustrate the point I'm trying to make) to see what I mean:

 

 

Also, when looking at Hupehsuchus itself, even though the pectoral girdle is highly damaged, the forelimbs do suggest attachment would have been such that the rest of the body-plan would also have been barrel-shaped (source: Wikipedia):

 

 

Likewise, I'd move the pelvic girdle down a bit as well (making sure to adjust the alignment of the gastralia in the process), as this not only seems indicated by the above specimen, but would also give the animal more range of movement in its hindlimbs. This could be achieved by either lengthening or straightening the ischium so that it stretches downward more, while, at the same time, maintaining contact with the lumbar vertrebrae. By way of illustration, here's the pelvic girdle of O. icenicus from the Paläontologische Sammlung of the MUT Tübingen - though in Hupehsuchus, it being a more basal species, the pelvic girdle would remain closer to the vertebral column than it does in Ophthalmosaurus.

 

 

In any case, to illustrate what I meant with the scapula and the pectoral girdle, I took the liberty of drawing my suggestions in overlay on top of your model. I hope this helps resolve your uncertainty

 

[Mahnmut]

Thanks again Alexander,

you made me re-research my sources. I kept my model very close to this drawing

https://www.geol.umd.edu/~jmerck/geol431/images/hupehsuchus.jpg

that seems to be the source of or from the same source as the one on the heretic site. My gastralia and pectoral girdle are very close to this.

So you think that even if the pelvis should be lower, it should stay in contact with the spine, not free floating like in whales? I was wondering about that.

I now also found this :

https://royalsocietypublishing.org/doi/10.1098/rstb.1991.0004

and finally understood how strange the osteoderms of Hupesuchus really are. It also shows one scapula, and it is indeed more fan-shaped.

I thought I was close to finishing that model, but there will be some more changes to do.

Those will have to wait a little bit though, as I have to finish one last homework before beginning my masters thesis. This being my second course of studies I do it besides working 30 hours a week. So You realize the true amount of procrastination that went into this model.

Below you see Hupehsuchus' osteoderms as they where NOT.  They where stacked above each other in the medial line. As I would have realized earlier if I had done a better recherche at first hand.

Best Regards,

 

Jan

 

[pachy-pleuro-whatnot-odon]

5 hours ago, Mahnmut said:

Thanks again Alexander,

you made me re-research my sources. I kept my model very close to this drawing

https://www.geol.umd.edu/~jmerck/geol431/images/hupehsuchus.jpg

that seems to be the source of or from the same source as the one on the heretic site. My gastralia and pectoral girdle are very close to this.

No problem at all, Jan! In order to answer your questions, I, too, am learning quite a bit about aspects of ichthyopterygians I hadn't before considered overly much - and I enjoy the research

 

If I look at the image you're using as a reference for your model and the one posted on ReptileEvolution, to me it seems like both might actually be based on the original figure 5 from Carroll and Zhi-Ming (1991), which article you linked above... Oddly enough, though, it seems like they forgot to include the scapula in that reconstruction 

 

5 hours ago, Mahnmut said:

So you think that even if the pelvis should be lower, it should stay in contact with the spine, not free floating like in whales? I was wondering about that.

In modern whales the pelvic girdle is vestigial and does not serve as support for a pair of hindfins. In animals that have hindlimbs, however - the pelvic girdle needs to be attached to the spine to provide anchoring and stability for these extremities, be the animal aquatic or terrestrial. Yet, at the same time, in aquatic animals the pelvic girdle should be positioned as far away from the spine as possible to ensure as great a freedom of movement in their environment as possible. Thus, the better adapted an animal is to their aquatic environment, the further the pelvis will lie from the spine - all the while while remaining connected. Hupehsuchus being a basal ichthyopterygian, however with significant aquatic adaptations, it stands to reason that its pelvis would be at intermediate distance from its spine. Thus, somewhat lower than what you have right now...

 

6 hours ago, Mahnmut said:

I now also found this :

https://royalsocietypublishing.org/doi/10.1098/rstb.1991.0004

and finally understood how strange the osteoderms of Hupesuchus really are.

[...]

Below you see Hupehsuchus' osteoderms as they where NOT.  They where stacked above each other in the medial line.

 

Interesting! I didn't know Hupehsuchus had osteoderms! This seems very unusual for ichthyopterygians, but does, I guess, explain the name "suchus". It also shows more similarity to the variability in early sauropterygians  Looks pretty awesome in any case!

 

6 hours ago, Mahnmut said:

It also shows one scapula, and it is indeed more fan-shaped.

Cool! I'm glad to see my intuition proved right, as it was rather an educated guess based, in part, on comparative anatomy, as well as consideration of both Hupehsuchus and Mixosaurus being small basal ichthyopterygians...

 

7 hours ago, Mahnmut said:

I thought I was close to finishing that model, but there will be some more changes to do.

Those will have to wait a little bit though, as I have to finish one last homework before beginning my masters thesis. This being my second course of studies I do it besides working 30 hours a week. So You realize the true amount of procrastination that went into this model.

Sorry for that!  But I hope your model will end up the better for all the work you're investing

 

Good luck, 

Alexander.

[Mahnmut]

Aloha,

just gastralia and realistic osteoderms missing. I lost the scleral rings(there have none been found) and the anatomy of the head makes much more sense now that I found the original drawings. Taking Alexanders ideas into acocunt I put the pelvic and pectoral girdles slightly lower.

Best Regards,

J

 

 

[pachy-pleuro-whatnot-odon]

Looking very good, Jan! Looks much more natural to me now!

 

As to the sclerotic ring, however, keep in mind that absence of evidence is not necessarily evidence of absence. Especially with such a small creature the bones of the sclerotic ring would've been so thin and fragile as to have preservation work against them. Thus, no sclerotic ring having been found with the original specimen described by Carroll and Zhi-Ming (1991) doesn't seem so surprising, especially not when various parts of the rostrum of that specimen have also not been preserved.

 

If you look at the specimen I posted from Wikipedia above, you'll observe that the preservation is quite different. While much of the pectoral girdle is absent from this example - probably due to the break and may be excessive preparation surround it - the skull is in a much better condition. Below is another copy of the same image, this time focussing on the cranium. In it, you'll observe that the orbits, compared to the described specimen, are filled with bone. And while it's difficult to make out the exact bone structure that's filling the orbits, and thus their origin (might be other skull elements), it seems reasonable to assume presence of a sclerotic ring. That is because presence of a sclerotic ring seems to be an ancestral condition to many reptiles, whether they belong to archosauria (crocodiles, dinosaurs, bids, pterosaurs) or lepidosauria (snakes, lizards, mosasaurs). Moreover, sclerotic rings are frequently not recovered when fossils are found, adding to the arguments for "absence of evidence, ...".

 

 

However, do think that the sclerotic ring in Hupehsuchus would've been a lot larger than you originally made it, which appeared rather ichthyosaurian. Yet, Hupehsuchus, of course, was a very basal ichthyopterygian and would, as such, probably have had a sclerotic ring still very close to that of the lizard-like ancestor it evolved from. In support of this argument, and as Mixosaurus turned out to be such a good analogue for the scapulary shape as well, here are a photograph and diagram describing the sclerotic ring in Mixosaurus:

 

(above) a. Triassic ichthyosaur (Mixosaurus); (below) b. Jurassic ichthyosaur (Stenopterygius). Source: Museo Civico dei Fossili di Besano

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mixosaurus at the Paläontologische Museum Zürich

 

 

 

 

 

 

 

 

 

 

 

 

The sclerotic ring in Mixosaurus was absolutely huge, filling the entire orbit. Now I know arguments have been made concerning more derived ichthyosaurs with respect to the size of sclerotic ring arguing for deep-diving behaviour (actually, activity in low-light conditions, as in terrestrial species large size of the sclerotic ring is often taken as indication for nocturnal behaviour). But in early ichthyopterygians, I'd argue the large size of the sclerotic ring is rather a remnant of the ancestral condition seen in lizards. As such, and when reconstructed more three-dimensionally, I'd expect Hupehsuchus to have a sclerotic ring not dissimilar to that of the Uroplatus phantasticus gecko below:

 

Source: Wikipedia

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Anyway, just thought I'd mention this. As per usual, it is, of course, entirely up to you to decide what to do with this. Last I want is for you to get overworked on a Hupehsuchus-model