Monthly Archives: July 2013

Tapejara pelvis and legs

I’m still don’t have all the information for the pelvis, but I decided to start doing it anyway. My only source are the images of SMNK PAL 1137 from the article by Eck et al, which are in black and white, low resolution and have at most two views of each bone. I will have to use what I know about other pterosaurs to make it three-dimensional.

I started cutting out the parts in scale (the scale is another big problem – I based my choice on information from paleontologists since the scales in the article are not reliable).

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Then I  folded and tried to shape each bone trying to guess the depth of its three-dimensionality from the shadows. I also used as references all I learned about pterosaur pelves so far, but I never made one from the individual bones before.

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This is a prototype. The pelvic bones are actually a set of four bones on each side forming the pterosaur’s hips. It’s supposed to look something like this. The long one on the left is the ilium (the long part of the ilium is actually called the preacetabular process). On the right, above is the postacetabular process. The depression near the right side of the ilium, which forms a circular shape if you consider the other two bones below is the acetabulum. That’s where the femur will articulate. At the lower left is the pubis and at lower right, the ischium. The point where the ilium, pubis and ischium fuse together is the acetabulum.

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Here I added some more detail, did some fire shaping and coffee-staining. It’s still a prototype for testing (I might change it or throw it away after I use it). You can see better now the three-dimensional aspect of the ilium, showing the acetabular depression, and the medial side of the postacetabular process.

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The process I used to make the femora and tibiae is the same I used for the other long bones (humeri, ulnae, etc) so I won’t detail them here. This is a picture of the strips of foam I used to make the bones of the legs. One of the femora is already with its halves glued in place.

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The tibia is actually a set of four bones called the tibiotarsus. It contains the tibia itself, the fibula (a very thin bone fused to one of the sides of the tibia, starting at the proximal end and not reaching the distal end), the calcaneum and astragalus which are actually part of the feet (they are the proximal tarsi which function as hinges for the feet). The picture below shows the tibia-fibula and the calcaneum-astragalus parts.

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Now we can try assembling the whole set, so see how it looks. In the upper part of the image below is an unassembled pelvis, a femur and a tibiotarsus, and at the bottom an assembled pelvis with an articulated femur and tibiotarsus.

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Here I tried to fit them in place with my fingers.

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But it’s easier with pins. The image below shows a tibiotarsus, femur, and an assembled pelvis.

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There is still a lot of work to do on the pelvis, and I should return to it next week when I will try to connect them to the sacrum, and finish the pelvic girdle.

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Tapejara wings

The wing is a giant finger, and fingers are connected to the radio/ulna pair by several small bones called carpals and metacarpals. I’ll leave the carpals for another opportunity and concentrate on the metacarpal and four phalanges of the wing.

The wing metacarpal is a big bone, about the size of the radius and ulna and even wider on one end. The wider end articulates with the radio-ulna pair through the carpal bones, and the other is a hinge for the first phalange of the wing – the longest bone in the Tapejara body.

I used SMNK PAL 1137 as a source, but had to rely on Tupuxuara for some details. They are similar. I got the length dimensions from Brian Andres’s database (scaled 25%). I used the same process I employed on the other long bones. Cut two halves, shape, glue together, fix with fire, add ends in thicker foam and reshape.

IMG_5371 IMG_5376 IMG_5381 2013-07-24 18.00.09

After the metacarpal comes the long first phalanx. This one I could rely on a picture I have from IMCF 1061 (which was perfect, since the quality of the pictures in SMNK PAL 1137 is very bad).

This bone has a flattened shaft, so it has greater resistance to anteroposterior forces than to dorsoventral ones.

IMG_5350

You can see I added a thin strip of plastic to the middle of the bone. Does that increase resistance? I measured it. A strip of 2mm foam 20 cm long  and 7mm wide attached on one end (1cm for attachment) can support 7 grams on the other end before folding (forcing the weak narrower side). Treating it with fire made it resist more, but it cracked with 9 grams. The phalanx has two of these strips, and is a bit hollow (I glue them on the edges, slightly curved). I made a prototype which supported 20 grams before cracking. Adding the strip won’t keep it from bending, but will avoid a destructive bend in one place or cracking. I expect that resistance to increase when I add the acrylic resin, and even more after the epoxy resin coating. Anyway, the maximum of weight the phalange will have to bear (considering only support on the proximal end) is 7 grams (considering the other three phalanges already coated with resin and epoxy and connected with silicone rubber). They currently weigh less than 5 grams (no epoxy coating yet) and they still have some water from the acrylic resin to evaporate.

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Here are the finished bones of the first phalanx compared to an unfinished humerus and the neurocranium.

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Some closeups and other angles.

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Testing the articulation with the metacarpal.

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The articulation with the radius-ulna pair is still not possible because there are yet no carpals.

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Next step: the other three phalanges. In fact I already had them all cut out and the haves attached before I did metacarpals and radius-ulna pairs. All these unfinished bones fit nicely on top my computer.

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So I tested the wings before I made these bones.

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And here is the final result. I used IMCF 1061 as sources for phalanges 2 and 3, and Tupuxuara for the last phalanx. I also used measurements from Brian Andres (scaled 25% as usual, since this is a larger specimen).

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Here is a detail of the last phalanx and articulation.

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And the full wing (I still hadn’t finished the humerus).

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Now we can place the bones on a surface and imagine the full skeleton.

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Tapejara arm bones: humeri, radii & ulnae

I should have finished the head and the spine by now, but I am waiting to get better sources and images, so I decided to change my schedule and work on the long bones. This post is about the arm bones: the humerus and the radius-ulna pair.

I am using as sources the images from SMNK PAL 1137 (which unfortunately are in low resolution and black and white). For the humerus I also had four colour views from IMCF 1061. I am using the dimensions which the paleontologist Brian Andres sent me, which I increased by 25% (since this Tapejara has a 2m wingspan).

I made each bone from two halves of 2mm foam sheets. Since the shafts of the humerus, radius and ulna have a round section (in contrast to the wing bones which are somewhat flat), I drew the parts about 30% wider in that part, and left a bit extra at the ends to allow cutting and reshaping.

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After cutting, I shaped the foam and glued the two halves in place.

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This is a view of one of the ends.

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After I did that with both humeri, I reshaped and lightly applied some fire to trim the edges.

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Herre are the two humeri compared to a humerus from Tupuxuara leonardii.

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In the picture above, I just filled in the bone ends with thicker foam, which allows some sculpting. After drying I then gave it some more treatment with fire.

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This is the final result so far. I will further improve this after adding resin and coffee stains.

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This is the humerus after resin and stains. it still needs some sanding and trimming.

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I based the ulnae and radii on SMNK PAL 1137. It seems they are the same size (if the scale is correct) and that they are almost the same width (some pterosaurs have a much narrower radius). I didn’t curve the radius like the picture. Here is a pair of ulnae before assembly.

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And this is after gluing the halves together and trimming with fire. I still have to make the bone ends.

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After adding the bone ends, and some trimming, I could finally try to fit them together.

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Here are some views of the finished arm bones: humeri, ulnae and radii:

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Tapejara’s dorsal vertebrae

Here is a picture of Tapejara compared to an unknown thalassodromid comparing skull and neck. 2013-07-16 12.45.53

But this post is about the vertebrae that come after the neck: the dorsal vertebrae. The first four to seven of these vertebrae is fused in most adult pterosaurs to support the pectoral girdle and is called the notarium. There is no fossil evidence that this occurred in Tapejaras, but none of the specimens used are considered “full grown adult” either (I’m referring to the ones that were published). Some decisions that affected the dorsals also involved the cervicals, so I might also talk a bit about them here.

I had some trouble with my sources. I used the same ones I had used for the cervicals, but several images published in the article about SMNK PAL 1137 had the wrong scales, so the sizes didn’t match. Not even the reconstructions using the bones from the same specimen matched, and the descriptions confused me more than they helped, so I had to rely on other sources. MN 6588-V has several dorsal vertebra but it’s not really a tapejara, and it also has an incompatible scale: if I match the size of the cervical vertebra in that specimen, all the others become too small.

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So I decided to trust the scale I was originally using (from IMCF 1061) which unfortunately has no dorsal vertebrae, and to estimate the size based on Tupuxuara. The problem is that Tupuxuara’s cervical vertebrae are proportionally shorter, and so is the pelvis, so maybe the Tapejara has a narrower and longer body than the Tupuxuara, or maybe it just has a proportionally longer neck. I don’t know.

I checked other reconstructions (drawings and sculptures), but they seem to either have fewer cervicals, or identical cervicals. I observed that both in Tupuxuara and Tapejara (Iwaki specimens) there are some longer cervicals and others which are shorter and taller. I am not sure about the order, but in the (unpublished) Iwaki specimen, they were numbered, and the two shorter ones were cervicals no. 3 and 5 (not counting Atlas/Axis). I don’t know how accurate that ordering is since there is no publication, but I assume they either knew before preparation or they fit somehow, and since that’s the best information I have, I followed that same order in Tapejara.

I decided to not use any reconstructions as sources except my own. I used the four dorsal vertebrae from SMNK PAL 1137 as sources ignoring their  (incorrect) scale, adding broken and missing parts, and tried to fit them with the eighth cervical vertebra, using the Tupuxuara notarium as a reference but making each vertebra a little wider. After trying out three different prototypes, I could finally start making a final version.

I used foam strips for the processes and thicker foam for the vertebra’s body.

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After fitting the processes together, I separated the vertebrae to add details (processes) to each one.

Here are some views of the vertebrae after molding with fire, but before adding modeling resin.

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And here some more views after resin and staining with coffee.

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These are the dorsals that are part of the pectoral girdle, and which will articulate with the scapula. The exact number of dorsals after them before the sacrum seems to be unknown. Most reconstructions draw six notarium vertebrae + three to four free ones + two to three pelvic dorsals before the sacrum (that means 5 – 7 more dorsals), but other authors mention 10, 12. It seems that there is not enough evidence to be sure. I am also not sure about their shape. Do they get smaller, narrower, wider?

I don’t mind reading dozens of publications. It’s great. They revealed that many of my assumptions were bad theories, but they usually don’t offer me a solution. They open a discussion. And so, the more I read, the harder it is to make decisions, and I also reach the point where paleontologists disagree. It’s a fantastic discussion, really, but I have a deadline, so I have to make some choices. If they are bad, I will try to fix it before I deliver the skeleton.

So I decided to make 9 more dorsals (a total of 15). Three will be fused to the pelvic girdle, and the other six will be free. This is a first 3D sketch (the body and the spine of six dorsals).

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After adding the processes and splitting.

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After acrylic resin and staining.

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They are not really finished: I’m using them as prototypes so I can continue the work. Later I might reshape them, cut some excess foam, make them thinner, narrower, or even throw them away and make new ones. For now they just need to be functional.

I’m trying to find reliable information to make the pelvis. The only sources I have are SMNK PAL 1137 (just pelvis, no sacrum, one or two views of each bone and no more), and a side view from MN 6588-V. I would be nice to have other views. I’ve been trying to obtain permission from the Iwaki museum so I can have access to all Tapejara photos (I only have some), but so far I haven’t received any response. I might have to continue without them, unfortunately.

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Tapejara cervical vertebrae

with neck 1

I got a bit behind schedule this week with some other projects but I was able to recover half of the time this weekend and get the cervicals done. Now Tapejara has a neck, as shown in the picture above.

I started gathering all the data I had which included cervicals from 4 different specimens. The SMNK specimen is smaller than the others. I used the IMCF specimen as a reference, double checked by comparing the size of the cervical vertebra in the AMNH specimen. I also used Tupuxuara vertebrae (from IMCF 1052) scaled to the same size as the Tapejara because of its better resolution and because it has a complete collection. But the IMCF, SMNK and AMNH vertebrae are all proportionally a bit longer and narrower than the Tupuxuara vertebrae, so I made considered that as well. Here I placed all of them in scale.

research_no_IMCF

I started with some prototyping and made hollow cervicals (as I did before with Tupuxuara). This time I used 2mm XPS foam (instead of the 5mm foam I used in Tupuxuara) since the Tapejara vertebrae are less than half the size of Tupuxuara vertebrae.

prototype 1 prototype 2

After assembling, gluing, shaping, adding texture and molding with a lighter, we have a prototyped vertebra.

prototype 3

From those prototypes, I cut out the foam in this pattern for vertebrae 1, 2 and 4 (3 and 5 have a slightly different shape, a bit taller and shorter).

final prototype

Here are the five vertebrae, after assembly and shaping with a lighter.

cervical rod

After finishing all 8 (or 9 if the fused Axis/Atlas are considered 2), I made a spinal cavity in each one, and crossed it with a wooden skewer. Here is the Tapejara with a stiff neck.

stiff neck

As I did with Tupuxuara, I used a rubber tube (4mm diameter) as a spinal cord.

medulla

Here are the Axis/Atlas and seven other cervical vertebrae connected with the tubular medulla.

cervicals connected

The last two vertebrae are slightly shorter.

last cervicals

The neck is assembled connecting the vertebrae. It retains some flexibility (less to the sides, more up or down).

neck

And finally the Tapejara with the neck in place. It’s still not possible to attach it, since the skull still lacks several posterior bones.

curved neck

Tomorrow Tapejara will have some thoracic dorsal vertebrae.

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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.

nc_side

nc_front

nc_under

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

front1

top1

back1

side3

side1

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Tapejara skull, part 3: neurocranium, quadrate, lacrimal

I made nearly all the bones of the skull. Some smaller ones inside the skull are still missing as well as the occipital. I also worked on the bones with a lighter for texture, shaping and hardness. Here is a partial assembly with the larger bones almost finished.

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These are the parts: rostrum/palate, neurocranium, mandible, one of the quadratojugals and one of the quadrates.

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Here are some views of the almost fully assembled skull. I didn’t glue the parts together yet; I just pinned them in place.

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The neurocranium, orbits, lacrimal, etc. still lack some detail, and there is no occipital bone yet.

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These are all the detachable parts so far:

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