Somewhat fishy

[Mahnmut]

Thanks!

 

Issac,

I have been tinkering with blender for some years now, mainly twisting and mixing existing skeleton scans with the mesh modifier, which is a powerful tool and keeps the detail of the real bones, like here: http://www.thefossilforum.com/index.php?/topic/97806-neogene-ungulates .   Adding reference images from different perspectives into your scene is the main trick here. But only very recently Thorst gave me some hints on how to build complete skeletons relatively easily.

The main trick is to build simple geometry and to apply the subdivision surface modifier as a second to last step, only adjusting detail afterwards.

Also very helpful is the mirror- and array modifier, because so many bones are metameric, meaning repeating in similar ways, and nearly all are bilaterally symmetric.

Below you can see how few actual vertices make up a rib, or actually 10 of them, because they are multiplied by the mirror-and array modifier. There is still a lot of refinement necessary, but it is much easier to change the  overall proportions as long as you keep the geometry simple.

Maybe you already know all this, but for me these where the main eye-openers that made the Hupehsuchus and the following models possible, I watched some hours of tutorials over time, and as always with blender, there is still a lot to learn. Just two days ago I learned to use "parenting" in order to move for example all phalanges with the arm, but not the other way round. Saves a lot of trouble.

Cheers,

J

 

[pachy-pleuro-whatnot-odon]

I never really got off too much with Blender, as it seems to have rather a steep learning curve. Instead, I used to do much more in 3D Studio Max, and especially Cinema 4D, which is a very powerful and intuitive tool thanks to its graphical user interface. The main problem here, of course, is that, much ids in Photoshop compared to The GIMP, these are paid packages...

[IsaacTheFossilMan]

4 hours ago, Mahnmut said:

Thanks!

 

Issac,

I have been tinkering with blender for some years now, mainly twisting and mixing existing skeleton scans with the mesh modifier, which is a powerful tool and keeps the detail of the real bones, like here: http://www.thefossilforum.com/index.php?/topic/97806-neogene-ungulates .   Adding reference images from different perspectives into your scene is the main trick here. But only very recently Thorst gave me some hints on how to build complete skeletons relatively easily.

The main trick is to build simple geometry and to apply the subdivision surface modifier as a second to last step, only adjusting detail afterwards.

Also very helpful is the mirror- and array modifier, because so many bones are metameric, meaning repeating in similar ways, and nearly all are bilaterally symmetric.

Below you can see how few actual vertices make up a rib, or actually 10 of them, because they are multiplied by the mirror-and array modifier. There is still a lot of refinement necessary, but it is much easier to change the  overall proportions as long as you keep the geometry simple.

Maybe you already know all this, but for me these where the main eye-openers that made the Hupehsuchus and the following models possible, I watched some hours of tutorials over time, and as always with blender, there is still a lot to learn. Just two days ago I learned to use "parenting" in order to move for example all phalanges with the arm, but not the other way round. Saves a lot of trouble.

Cheers,

J

 

Yes, the array modifier really is a powerful tool, along with the mirror. Make sure you apply the modifications, with ctrl+a, or the dropdown arrow, though!

One of my favourite tools is to select a group of faces, go into the edit mode, click 'smooth', and swipe right, to select 'randomize'. You can then very slightly randomly tweak the vertices or faces, and, afterwards, make sure to click ctrl+t, to turn the polygons into triangles... It's a very nice tool to use on low poly models, or, if you wanted to deform a bone, you could use it there, I guess. It doesn't really work as well with photo-realistic things like yours!

[Mahnmut]

Thanks for the feedback!

Back to palaeontology:

I never really understood gastralia, paying not much attention to the "ossified sixpack".

Now that I try to build a detailed model of a Sauropterygian, I realize there are different ways to arrange them. In Theropoda I was flubbergasted to learn that they where arranged in an interlocking zig-zag pattern, not perfectly symmetrical!

In Hupehsuchia there seems to be a medial row of v-shaped bones, and a smaller row to each side, maybe Helveticosaurus is similar..

Plesiosauria seem to have a ton of gastral ribs, but I am not sure on their orientation, does someone (@pachy-pleuro-whatnot-odon?) know a good overview on that topic?

Cheers,

J

 

[pachy-pleuro-whatnot-odon]

The thing about gastralia is that you need to understand their origin and how widespread their presence actually is. For, gastralia are actually an ancestral condition to all tetrapods, inherited from our lobe-finned fishy (rhipidistian/sarcopterygian) ancestors. Those animals that don't have them, such as mammals, have simply lost them along the way - a point suggestive illustrated by certain animals having homologous cartiligenous elements (transitional, on their way out?). They form the sites for muscle-attachments that, one can imagine, would've provided lobe-finned fish with greater abdominal rigidity for increased power in their fins. Gastralia have, however, been co-opted for all manner of other purposes in tetrapods: crocodilians use them for abdominal support (and probably also to support their sprawling gait); birds use them to provide their chests with more rigidity and as a sturdy attachment site for flight-muscles - as may pterosaurs; turtles have turned them into a plastron for ventral protection; and theropod dinosaurs may have used them to improve breathing (from which perspective it's interesting that in theropod dinosaurs gastralia are arranged in a partially overlapping interdigitating pattern, which I think may have allowed them to slide past each other to inflate and deflate the chest?). What they were used for in plesiosaurs, I don't really know, but I remember an argument being made about them providing additional rigidity for the plesiosaurian way of locomotion: modified sub-aqueous flying. 

 

In any case, plesiosaur gastralia are round in shape (except where they press into one another, in which case they may be slightly flattened and thus sub-rounded), osteologically very dense (there is no observable vascularisation or cancellous bone), and taper at the ends. Other than that, I haven't ever looked at or read about gastralia too much, and I actually wonder how much academic attention they have received in general - being, as they are, rather uninteresting parts of plesiosaur anatomy, oft not even included in systematic species descriptions (at least, not as memory serves me). I therefore took recourse with my collection of reference photographs, some of which are included below:

 

Liopleurodon ferox at the Paläontologische Sammlung of the MUT Tübingen

 

 

 

 

 

 

 

 

 

 

 

Peloneustes philarchus at the Naturmuseum Senckenberg in Frankfurt

 

 

 

 

 

 

 

 

 

 

Cryptoclidus eurymerus cast at the Naturmuseum Senckenberg in Frankfurt

 

 

 

 

 

 

 

 

 

Plesiosaur skeletal cast (probably a cryptoclidid) at the Paléospace l'Odyssée in Villers-sur-Mer

 

 

 

 

 

 

 

 

 

 

Careful study of the above photographs will make clear that plesiosaurian gastralia form shallow arches on the animal's ventral side, each made up out of five parts (the Liopleurodon skeleton shows four, but I expect this to be an error in the reconstruction, as the gastralia of the same museum's C. eurymerus skeleton is a complete fantasy art-piece). One part lies perfectly medial to the skeleton, and may have a thickening in its centre - as is the case with the Peloneustes above. Two further gastralia (sections?) on either side extend the length of this central part, with an overlap of one-third to half a length existing between the sections that make up the parts of each arch. The density of arches is unclear and may differ from species to species, although it is likely that the densities shown in the above photographs are simply artefacts of imprecise museological reconstructions - which just goes to show low little attention gastralia are typically awarded.

 

Hope this helps!

 

P.s.: As a bonus, here's a couple of photographs of the Liopleurodon ferox from the Paläontologische Sammlung at the MUT Tübingen for reference. Note that compared to this your model's tail is too long, belly too shallow, and skull too massive and tall (though note that the skull of the specimen at MUT has significantly been reconstructed). There's an issue with the spinous processes on the vertebrae as well, as they drop in height along the trunk of the model - which might indicate the vertebrae (still) being too small.

 

[Mahnmut]

Thanks, that was indeed helpful.

 

concerning my model, thanks for the comparison. the seemingly long tail may be an artifact though, as I turned of "perspective ortho" for that screenshot, because the head apeared huge otherwise. The spinal processes are still to be fine-tuned, I just quickly adapted the overall proportions.  Looking at the flippers I realize they need another look too.

Best Regards,

J

[pachy-pleuro-whatnot-odon]

No problem! Let me know if you need any other photographs of more specific parts. I may be able to help, as I do have some more material from this one specimen

[Mahnmut]

Another aquatic reptile. Now there are three in the pipeline, it is kind of a batch process. First ribs for all, then vertebrae, skulls are most fun... fine tuning will nee some time for all of these. I also plan to include Atopodentatus (maybe also the wrong reconstruction for good measure).

Cheers,

J

[pachy-pleuro-whatnot-odon]

4 hours ago, Mahnmut said:

 

Cool! You're indeed really spitting these out with speed now!

Looks like Tanystropheus? If so, the position of the neck and extremities still looks a bit off. Have a look at Mark Witton's posts to see his reconstructions (part 1, part 2).

[Mahnmut]

Thanks!

the fine adjustments will take some time. Yes, this is supposed to be Tanystropheus, changing it to a Dinocephalosaurus will be easy.

Its swimming pose is modelled after this:

https://idw-online.de/de/attachmentdata80498.jpg

Skull after this : https://www.researchgate.net/figure/Figure1-Interpretations-of-the-skull-of-adult-Tanystropheus-longobardicus-exemplar-q_fig1_328827519

 

I wonder what the bones below the tail are, labeled "het." in "GMPKU-P-1527, as depicted by Rieppel et al". in Wittons blog entry.

Perspective is of course extreme in my picture. Feet and tail are placeholders.

Salut!

[IsaacTheFossilMan]

4 hours ago, Mahnmut said:

Another aquatic reptile. Now there are three in the pipeline, it is kind of a batch process. First ribs for all, then vertebrae, skulls are most fun... fine tuning will nee some time for all of these. I also plan to include Atopodentatus (maybe also the wrong reconstruction for good measure).

Cheers,

J

Goodness me you're fast at this... Gorgeous, simply gorgeous! What're you planning to do with the models, if I may ask?

[Mahnmut]

OK, , het means "heterotopic ossifications". Maybe ossified cartilage.

[IsaacTheFossilMan]

1 minute ago, Mahnmut said:

OK, , het means "heterotopic ossifications". Maybe ossified cartilage.

Interesting...

[Mahnmut]

https://www.researchgate.net/publication/235744894_Tanystropheus_cf_T_longobardicus_from_the_Early_Late_Triassic_of_Guizhou_Province_Southwestern_China

 

There are three main reasons I am that fast:

-I can now use the parts I made for Hupehsuchus, adjusting only details and proportions

-I did not adjust the details yet, that will take at least as much time as putting together the basic shape

-I should be doing something else just now. ^^

 

First of all these models will join my growing private menagerie of the extinct. I wonder if a museum may be interested when I get still a little bit better.

Until now most of my models where handmade and unique. (For the Majungasaurus I made on commission I still did not get around to making another one for myself).

These on the other hand can in principle be replicated easily (Eagerly waiting for the first print). I will let you know how that works out.

 

Aloha,

J

 

 

[IsaacTheFossilMan]

3 minutes ago, Mahnmut said:

-I should be doing something else just now. ^^

Best reason to be doing something speedily!

[pachy-pleuro-whatnot-odon]

1 hour ago, Mahnmut said:

OK, , het means "heterotopic ossifications". Maybe ossified cartilage.

 

"Heterotopic ossification" would mean abnormal bone growth, not necessarily cartilage, but just something one doesn't normally finds in regular anatomy. In Tanystropheus (the longobardicus species anyway), however, this seems a usual anatomical feature, one that may have served to provide the tail with additional stiffness and stability, which, one imagines, itself may have served to provide counterbalance to the neck. In any case, this bone growth would not have made the tail very suited for carangiform swimming. With the overall Tanystropheus body-plan also not appearing very suited to anguiliform swimming, I'm rather in favour of Witton's croc-o-heron model over any aquatic lifestyle for Tanystropheus.

[thorst]

Wow three models in just a few weeks - stunning! And the results are really nice! Congratulations!

[Mahnmut]

Thanks!

@thorst, you really started something when setting me on blender!

Wittons arguments for a coastal lifestyle are quite convincing in  my eyes.

Dinocephalosaurus will have to stand in for my aquatic quartet. And concerning the calcified cartilage, it seems that teh cartilage-like porosity of the fossil may be due to diagenesis. So, it is just a couple of bones we cannot homologize, thus heterotopic.

 

Best Regards,

J

 

[IsaacTheFossilMan]

@Mahnmut you should make some sort of virtual museum app with all your models in, and just a simple player controller, with like information stands next to them! No point to the 'game' or 'app', I don't think it'd count as a game, but it'd just be an awesome way to see your absolutely stunning models from all perspectives! I think they'd benefit from a really minimalist setting... That's just my suggestion though, carry on as you were, awesome awesome work!

[Mahnmut]

Got a 3d printed egg today.

[Mahnmut]

[Mahnmut]

[IsaacTheFossilMan]

Awesome!

[pachy-pleuro-whatnot-odon]

Very cool! So that's how commercial 3D-printers deliver the model you request? They pack the model for most efficient stacking and then encapsulate it in plastic netting to protect it during shipping? You need to cut it out yourself? Very interesting procedure...!

[Mahnmut]

The efficient stacking was done by me.

The netting is something you can order if the part count makes the model to expensive or to fragile to handle. They also told me it was unprintable, so no guarantee.

Turned out well except some phalanges.

Good night!