Tapejara: improvements and fixes

All the bones are finished. Time to add a protective resin layer and to make some small fixes. Here are some of them drying after receiving a layer of epoxy.

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All the bones already have a resin layer except for the cervicals, anterior part of the skull and the scapula-coracoid pairs. I have to improve them using the images from IMCF 1061 which I received. They are simple fixes and not as complex as the neurocranium.

The easiest is the scapula-coracoid pair. I had to discover how to connect them before hardening (when they only have an acrylic polymer layer they can still be twisted, heated, and slightly reshaped.) So I did some research and finally discovered how the coracoid and scapula should articulate.

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The skull needed reinforcements on the inside, lacrimal and post-orbital bones. I didn’t find fossil evidence in Tapejaras for the large triangular cavity in the posterior part of the palate, so I closed it (it seems there might be a small one, but I’m not sure). I had based the palate on other thalassodromid specimens, since the IMCF 1061 palate seems to be missing.

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This is the skull before adding the missing bones.

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And after

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Here are some pictures of the nine parts of the skull attached. The neurocranium and quadrates were attached to the rest with silicone rubber (they can be easily detached). The mandible joint was also made from “cartilage” of silicone rubber. It firmly keeps the mandible attached to the quadrate, but allows some flexibility (so the Tapejara’s beak can hang open).

final1 final2 final3 final4

My cervicals had posterior condyles which were too short and they all had missing anterior cotyles. Here is a picture of the vertebrae when I had “finished” them. The black lines show what is missing:

cervical rod

My first sources were very bad. I had to rely entirely on black and white photos from the SMNK PAL 1137 article, and I didn’t see the cotyles there. But then I received the pictures from IMCF 1061 and fixed the vertebrae, adding pieces of foam to form a small ridge under each vertebrae (or the cotyle), and three small tubes behind (for the longer postexapophyses and condyle). I forgot to photograph them while I was making the fixes. Here are some pictures showing the final result.

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cv1

cvstop

There are obviously many other details which can be improved. Since my sources are only photographs, and usually bad ones, I do what I can. The IMCF 1061 photos were great because they allowed me to see more details and improve the replica.

 

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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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Tapejara: caudal vertebrae

None of the Tapejara specimens I used as sources had a tail, so I used as a source Anhanguera piscator, which seems to be the most closely related pterosaur with well preserved caudal vertebrae. The source is Kellner & Tomida 2000, but I used photos of the tail I had made for Tupuxuara and scaled it to Tapejara proportions.

I made ten individual caudal vertebrae. This number is speculative, as is the shape of the last caudal vertebra. Anhanguera’s tail has dorsally projecting processes on the first four or five vertebrae, which change to lower anterodorsally projecting ones which get smaller and smaller as you get closer to the end of the tail.

Here are some photos. Yes, I made all the vertebrae hollow except for the last one. I thinned the foam a bit with fire.

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These are the final vertebrae.

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Tapejara: abdominal bones

These are experimental. There are not many museum casts out there with gastralia and pre-pubis. Not many pre-pubis bones are preserved, either. I used as a source the MN 6588-V tapejarid, scaled for Tapejara. It shows a pair of pre-pubis bones. They are flat, so I can only speculate about their shape, but since they articulate with the pubis, and gastralia bones, which articulate with the ribs to make a rounded belly, I believe they are concave on the ventral side. That’s also what reconstructions of other pterosaurs suggest. I am not sure yet if I will be able to use them, since there is a lot of speculation in that part of Tapejara’s body (unknown number of dorsals, sternal ribs, etc.)

Here is the pre-pubis I cut out of a 2mm sheet of foam, based on the MN 6588-V specimen.

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I made gastralia from pieces of foam like this.

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They are probably not thin enough. But hey, maybe this Tapejara had a stiff belly 🙂

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Tapejara: pelvic girdle

I already had made the pelvic bones, but the sternum complex was missing. I didn’t find any realiable source with a perfect sternum, so I used as a source the same azhdarchoid sternum that I used in Tupuxuara, and adjusted it so it would fit the Tapejara pelvis (from SMNK PAL 1137). They are 5 sacral vertebrae, and two dorsal ones with lateral processes fused to the preacetabular processes of the ilium.

I cut it out in one piece from a sheet of 2mm foam, and added the stacked vertebral bodies sculpted out of thicker (yellow) foam. Here are two views of the sacrum after treating with fire.

sacrum 2 sacrum 1

Four views of the finished sacrum.

lateral ventral posterior anterior

Next step: assemble the pectoral girdle. I now have all the parts.

parts

I wish I had smaller pins.

testing dorsal dorsal w pelvis testing lateral anterior with pelvis posterior with pelvis

I placed a rubber tube through the vertebrae acting as a spinal cord. It will be used to attach the pelvic girdle to the dorsal spine and to attach the tail on the other side.

ventral w pelvis

I now can test all the connections. Here is the Tapejara dressed in its pelvic girdle.pelvis and sacrum

A dorsal view.

dorsal assembly

And a ventral one. It’s almost finished. I’m already prototyping the pre-pubis and gastralia, but before I assemble the rest I will cover what I have so far with epoxi resin (I can’t use pins anymore).

ventral assembly lateral assembly

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Tapejara: pectoral girdle

The pectoral girdle consists of scapula, coracoid, sternum, dorsal vertebrae and ribs that grow from the vertebrae and from the sternum. I’m still having trouble figuring out how to assemble the scapula and coracoid. I read some articles and I haven’t discovered yet what most paleontologists think is the best layout. They seem to disagree in many aspects. Without twisting the bones quite a bit or setting the scapula to articulate with the first two dorsals I can’t obtain a low position. At best, the glenoid will stay somewhere in the middle of the chest. For now, I just pinned the proximal end of the scapula to the third dorsa, and the distal end of the coracoid to the sternum, so I could work on the rest of the pectoral girdle. But the correct way to connect scapula and coracoid is still an issue I haven’t resolved. Any help is welcome.

The ribs. I found some random ribs in fossils, but I preferred to use Wellnhofer’s reconstruction of Pteranodon as a reference to start with. I scaled them for Tapejara and made these sketches.

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I cut out the two first pairs.

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I made them hollow of course. This is a first prototype attached to the first dorsal vertebra.

rib testing

I quickly made some (generic) sternal ribs and connected their ends to the sternum and larger ribs to test the shape of the rib cage.

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Time to make more ribs.

more cut outs 2 first rib set

testing

The sternal ribs are thin but they have some lateral very thin bone pieces projecting laterally. It looks like some kind of ossified cartilage. How many ribs should be connected to the sternum? Some say seven lateral pairs, many reconstructions show four or five. The azhdarchoid MN-6588-V seems to have seven, and probably two more pairs behind. I chose five.

sternal ribs 2

Now the challenging attempt to assemble the pectoral girdle.

pectoral assembly parts 2

Somehow I fitted the scapula and coracoid in a way that revealed a glenoid and didn’t seem weird. The proximal end of the scapula is pinned to the third dorsal vertebra. If I project it a bit more laterally, it can move back more, but the sternum-coracoid articulation will also change.

ventral body 2

So now it looks like this.

ventral body lateral body

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Tapejara: shoulders and chest

I had two sources for the scapula and coracoid, and three for the sternum. For the scapula and coracoid I initially used SMNK PAL 1137 but then received better photos from IMCF 1061. The scapulae looked alike, but the proximal end of the coracoid was very different, it was also much longer. I don’t know if any part is missing or if it is just a result of SMNK PAL 1137 representing a very young specimen. Anyway, it is still very hard to identify and compare certain details when one photo is a bad black and white one with only two views. I decided to make the scapula and coracoid from IMCF 1061, and the sternum from SMNK PAL 1137 scaled by SMNK PAL 3985.

After estimating widths and depths from the photos, these are the flat parts I came up with. The yellow foam was used for the ends, which I had to sculpt.

cut outs scapulocoracoid

The parts after cutting out.

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Assembly of the scapula.

scapula assembly

Assembly of the coracoid.

coracoid assembly

Partial assembly of scapulae and coracoids.scap cora assemblies

This is the distal end of the scapula.

distal scap

And here is a set of coracoid and scapula after treatment with fire:

burned scap cora

Since there were many photos, I was able to compare several angles, and see where it was curved, thick, thin, and other details. This is another side view of the scapula.

side burned scap

The sternum is quite flat, so I initially made a shape slightly larger than the photo, so I could then give it a curved aspect.

stern cut out

But the keel I had to make separately.

keel

Here is a picture of the sternum with the keel attached shortly after treating with fire.

anterior sternum keel

And here is a side view after applying modelling paste and coffee stains.

lateral sternum

Compare it with the humerus.

sternum humerus

Now I have a big problem. How to assemble the pectoral girdle. I still didn’t figure out exactly which ends of the scapula and coracoid connect to form the scapulocoracoid. I might still have to twist the bone a bit since I may not have captured all the three-dimensional details from the photos. I spent a couple of hours trying different positions and gave up. Tomorrow I will try to assemble the pelvic girdle with ribs, and it might be easier. Here are the final photos.

dorsal sternum ventral sternum anterior sternum lateral scapula

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