Tag Archives: neurocranium

Tapejara’s Neurocranium revisited

I’ve finished practically all the bones. I still have to make a pair of lacrimals and post-orbitals. If I include them, the total bone count will be 198. But I will fuse the lacrimals and post-orbitals, as I did with the quadratojugals (gluing them to the skull with epoxi). So in the end, the total bone parts will be 194. These will be fit together with silicone rubber and other removable attachments.

I did not have access to reliable source for the occipital view, squamosal and pterygoid bones, since I hadn’t obtained authorization to see photos of the specimens which could help me with this. But ten days before my deadline, a paleontologist kindly sent me many more photos from the Tapejara specimen at the Iwaki museum (IMCF 1061). I’m not allowed to show them here, but I did my best to make this Tapejara replica as accurate as possible, so hopefully I captured their details in my sculpture, which you will be able to see here in many different angles.

I started with the neurocranium. First, I made the occipital crest shorter. It was way too long, and curved up. I cut it short.

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I had initially modeled the neurocranium from the SMNK PAL 1137 specimen, which you can see below. It has a partial occipital bone but it’s too short. It lacks most of the squamosal and the braincase is open. I can connect it to the rest of the skull with postorbital bones, lacrimal, and the parietal crest, but the bones which close the braincase and connect it to the palate (pterygoid, basioccipital, etc.) are missing.

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The SMNK PAL 1137 Tapejara specimen has an open braincase:

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But the IMCF 1061 specimen which has the missing bones will hide it. I started with two sheets of foam, glued and pinned around the edges of the braincase. I modeled it with a lighter to shape the bones (I don’t actually know the name of this bone – it might be pterygoid, epipterygoid, basioccipital… my anatomical reference guides do not include a pterosaur).

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Then I shaped a little more, practically closed the braincase leaving only a small hole at the back (foramen magnum) but still no occipital condyle.

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I also shaped the curvy squamosal bones.

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You can still see the braincase if you look through foramen magnum. Maybe I should have placed a little Tapejara brain there before closing.

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Finally I made an occipital condyle, added a layer of acrylic polymer emulsion (modeling paste) and stained with coffee. Here are some photos of the neurocranium attached with the rest of the skull:

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Here I also attached the mandible and the quadrate bones (the small squares are 5mm wide).

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I finished the neurocranium with a layer of epoxy resin, for protection and strength. Since it’s shiny it doesn’t look much like a bone anymore, but it looks a lot like a piece of granite. I will later add layer of matte varnish. If you have access to photos of the neurocranium of the IMCF 1061 specimen, you can compare them with these.

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Nobody is going to see the braincase when the Tapejara is assembled in the museum, but it’s nice to know that there is some space for a brain in there 🙂

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Unfinished Tapejara skull

To finish the skull I need to research details of the bones that form the base of the skull (occipital) and the inside, specially the bone(s) that pass between the optic lobes and connect the braincase/basisphenoid bone, to the occipital condyle and palate. I am not sure about what these bones are called. All the specimens I have lack that part. I think they are the pterygoid, epipterygoid and basioccipital. When I have diagrams or photos of these bones, I can finish the skull.

Of course I do have some sketches and a very simplified 3D model, and I could base it on my previous models, but that is “plan B” since I want to be as accurate as possible with this replica. So I decided to finish the skull later and start working on the vertebrae next week.

I finished the neurocranium and added a layer of acrylic resin. Before the resin, the full foam-only skull weighed 10 grams. Now it weighs 50 grams, but it should lose 50% of that weight when all the water evaporates. I also stained it a bit with coffee.

To model the neurocranium I used mostly SMNK PAL 1137. Here are some pictures.

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nc_front

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When I finish the skull, the braincase below might no longer be visible. Several bones and details from this view are missing.

brain

When I add the occipital bones (necessary to connect the cervical vertebrae) very little of it will still be visible.

This is a view of the skull from underneath, showing the mandible connected to the quadrate bones, and the back of the skull, which is mostly unfinished.

under

Most bones are just pinned in place. I will only glue them when I finish.

front top

front_bottom

side

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top1

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Tapejara skull, part 2: mandible and crest

Unlike my previous pterosaur reconstructions, where I made the skull with the final result in mind, this time I decided to model individual skull bones as closely as possible. This is investigative work and it allows me to test the connections, articulations and have a better understanding of its anatomy. I also believe that this will result in an even more accurate and robust model.

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Skull parts partially assembled.

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A quick & dirty assembly of all the skull parts.

Using several different specimens as sources, and reconstructions based on some specimens, I was able to compare details and choose the ones that were best preserved. I made and will make some changes based on that. The palate, for example, was initially modeled from a reconstruction based on AMNH 24440. I now plan to adjust it based on the perfectly preserved palate from IMCF 1061 (unfortunately I still have not received authorization to publish the original photos here so they can be compared).

The lower jaw (mandible) is practically finished. I just need to review it with the sources and make minor adjustments before working on the texture (with fire) and finishing it with acrylic modeling paste.

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The part which contains the rostrum, the crest, maxilla, palate, etc. and part of the caudal bones of the skull is also nearly finished, but I will have to fix the palate to adapt it to the IMCF specimen (I will merge them with the visible details of the AMNH specimen).

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I am now working on the neurocranium, which also includes part of the orbit, frontal, parietal, squamosal and a posterior crest. Making this separately will allow me to work on the details of the braincase, which will be partially visible.

There are some other smaller parts which I am making separately: two quadrates (which articulate with the lower jaw), two sets including the quadratojugal and nearby structures, and two lacrimal bones.  I decided to make these separately because they are very well preserved in several specimens, so I can focus on the details.

Here are some more photos of the Tapejara so far. In the next post I will publish photos of the neurocranium. The skull should be finished by the end of this week.

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Many thanks to Brian Andres, Hebert Bruno Campos and Felipe Pinheiro who provided me with information, sources and feedback which allowed me to improve this model.

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