Category Archives: Pterosaur #6: Caupedactylus ybaka

A new species of thalassodromid discovered in Brazil.

Imaginary pterosaur #6: an unknown thalassodromid/tapejarid

neck 2
“Hey Tupuxuara, this is your unnamed cousin! Can you lend me your neck for a minute? I need to take a picture!”

This reconstruction was based on photos that were on display at a website that sells fossils (Paleo Direct). It wasn’t studied, it has no formal identification and no name. Some paleontologists believe it has been adulterated, and one of them believes it’s fake. I think it might ¬†have been damaged, even altered, but not significantly. Well, if it really is fake, then I have made a reconstruction of an inexistent imaginary pterosaur… but hey! That is totally consistent with the project of this blog ūüôā

I made this one very fast. First because I didn’t have to do much speculative research. I used the source photos, and based the unknown parts on Thalassodromeus and Tupuxuara. Second, because I’m getting better at this. It still takes three days because I have to wait for the glue to dry before continuing. So I might work for 20 minutes, and wait an hour or two before working again for another 20 minutes. When I work in different parts of the skeleton I can be more productive. In this case, I worked simultaneously on the skull and on the mandible and was able to speed things up a bit. It took me three hours to make the first foam “3D sketch” of the skull. And then another three hours for the mandible and palate. Then I spent eight hours adding the little details (which make all the difference). And finally two more hours to finish it with resin and coffee.

The material I used was:

  • One 100 x 60 x 0.3 cm sheet of XPS foam
  • Scraps of XPS foam of other densities and widths for details
  • 50g of foam glue (PVA – Polyvinyl acetate diluted in alcohol)
  • 100 ml of acrylic resin (modelling paste)
  • Coffee (for stains)

And these are the final dimensions and weight:

  • Length (beak to rear crest): 63 cm
  • Width (jaw hinge): 12 cm
  • Height without mandible: 26 cm
  • Height with mandible: 30 cm
  • Mandible width: 10 cm
  • Mandible length: 47 cm
  • Total weight: 105 grams

The only dimensions I obtained from the fossil photograph were height and length (based on the length informed by the seller, since the photos had no scale information). The width was estimated using Thalassodromeus and Tupuxuara as referenes.

The skull should get lighter during the next couple of weeks, when the resins and glues dry completely (when I first weighed Tupuxuara’s skull it weighed 290 grams; One month later it weighed 220 grams).

Here are photos of the finished skull.

Side views



Dorsal view


Mandible (dorsal view)


Mandible and skull

side palate



With a neck

(Using Tupuxuara’s cervicals)

neck 1

Crest details

crest 4

crest 2

crest 1

crest 3

crest 5

Occipital views


jaw hinge

Intra-cranial views

inside 1

inside 2

Right orbit details


Palate details

palate 2

palate 3


Family photos

This is pterosaur #6 compared with pterosaur #5 (Tupuxuara leonardii).

with tupuxuara

And here is the whole Imaginary Pterosaur family so far: Guidraco (#1), Tupandactylus (#3), Anhanguera (#2), Dsungaripterus (#4), Tupuxuara (#5) and pterosaur #6.

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List of posts about pterosaur #6

Here is a list of all the posts related to the construction of this skull. Many of the techniques I used here I have detailed before in posts about the other skulls.

  1. A new species from the Cretaceous of Brazil
  2. Pterosaur #6: the palate and the mandible
  3. Pterosaur #6: details, details
  4. Imaginary pterosaur #6: an unknown thalassodromid/tapejarid (this post).

Sources and Acknowledgements

The only fossil source I used to make this model were four photos that were recently available at the Paleo Direct site (one of them I posted here). They aren’t there anymore. Besides that I had help from the paleontologist Hebert Bruno Campos, from whom I obtained information on the palate, mandible and skull details of the Thalassodromeus, used to fill the gaps.

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Pterosaur #6: details, details

The small little details take up more than half of the time, but they are what make the skull look authentic. I added several details in the skull, behind it, on the orbits, crests and palate. I used several techniques: creasing, burning, heating, melting with PVC glue, scratching, removing foam, adding foam, adding acrylic resin and staining with coffee. Here are some pictures.

The orbits stand out laterally. By folding and stretching the foam I was able to shape them well but one more layer of foam is needed to make it stand out as it should. This is the orbit before adding details.

orbit details 1

And after.

orbit details 2

Most of the crest details are obtained by heating the foam with a lighter. Not burn. The lighter has to move from the inside to the outside. The first time will barely cause any effect, but the foam will heat a bit. The second time it will shrink, and after that it will produce bubbles which make the effect you can see below. If you go beyond that it may melt or catch fire. If you previously mark anything with a pencil you won’t be able to erase it later. You can draw veins with glue, wax, paint, and when you heat the foam, that part will be protected so you can control which parts will stand out and which parts will sink in the crest.


After the fire I also added thin strips of foam for the crest details around the orbit.

crest details

I don’t know what the inside of the head looks like. Most of the time it’s not visible. After some research I did something like this for the Tupuxuara, and I decided to repeat it here.

inner skull details

This is the palate almost done. I’m working on the posterior part of the skull.

posterior skull details 1

Here I added some details around the occipital bones.

posterior skull details 2

Finally, I coat the foam with a layer of flexible and matte acrylic resin. It not only strengthens the foam making it less liable to crack, but it also protects it from corrosive chemicals which could melt the foam and reduces significantly its flammability. The foam becomes harder on the outside, but the resin is somewhat flexible, so it’s easier to rip a piece off than to crack it. I could also add a layer of epoxi resin to make it even more resistent and hard, but I usually prefer not to since that significantly increases the weight, changes the texture and leaves the skull with a shiny surface. I usually only add epoxi to the fragile parts (beak tips, and thin parts that stand out) and to surfaces which will be in contact (the jaw hinges). After the epoxi is dry, I scratch it a bit and add acrylic resin over it.


After the resin is dry, I make a cup of coffee and save the used powder to stain the skeleton. I usually sand the smooth parts before doing that (mandible, orbits, etc.) By adding powder multiple times, and rubbing firmly it with fingers, a toothbrush or lightly with a paintbrush, I can achieve different effects and make some parts darker than the others.


In the next post I will publish the final results.

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Pterosaur #6: the palate and the mandible

For the mandible I started with the side view picture from the original fossil, but it was partially covered and had no other angles, so I scaled the mandible of a Thalassodromeus to use as a reference.

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I cut the two halves, folded and molded a bit and then pasted them together. I also cut out the dorsal side.

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After fitting all the parts, I filled the open ones with smaller bits of foam.

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For the palate I used Tupuxuara as a reference, but also referred to the Thalassodromeus for the layout of the bones. I cut a flat palate + occipital bone from a sheet of foam, cut out the empty parts and folded it.

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I shaped the palate convexly to match the original fossil.

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And attached it in place.

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Pins aren’t enough to hold it in place while drying.

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The occipital bones were attached after the palate was dry.

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So now I have a rough 3D sketch of the skull. I used a lighter to melt away part of the foam and make an interesting spongy effect on the crest.

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I also used fire to shape the palate, the jaw hinge and the throat after the occipital bones were in place.

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It’s practically finished. Now we need to add the details, which takes up most of the time.

2013-05-16 09.10.27

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A new species from the Cretaceous of Brazil

In a few days I will travel with my pterosaurs to the 3rd International Symposium on Pterosaurs: Rio Ptero 2013. I decided to take some time and add one more skull to the family.

This fossil was on sale at Paleodirect but not anymore. Either it was sold or (hopefully) acquired by a paleontological institution. I am making the skull out of foam using only the few photos that were available online (unfortunately the link is now broken). This is the main photo.

Screen Shot 2013-05-14 at 3.38.00 PM

It consists of a full skull and mandible, and the first cervical vertebra and is about 60cm long. Compare it to the Tupuxuara (a Thalassodromid). If you look at the position of the orbit, the two crests, the mandible, you might say it’s a Thalassodromid. But if you look at the beak and the size of the head it might remind you of a tapejarid, such as Ingridia navigans, for example. It’s somewhere in between these two genera and it’s evidence that Thalassodromids and Tapejarids may be somehow related.

Since the rear part of the skull is very similar to the Tupuxuara, I will use the Tupuxuara as a model for the palate and the bones behind and inside the head.

I started out as usual, transferring the outlines of the fossil to a sheet of foam, scaled to the fossil’s dimensions. Since the heads of these pterosaurs are almost flat, I don’t have to compensate much of what I lose due to the 2D projection (I just compensate a bit around the orbits and below the mandible). Lost details I can always add later, with extra bits of foam.

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This is the final sketch.

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You can now finally see what it looks with the beak open.

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After cutting out the two halves I spent some time pressing, folding, and shaping the foam to make it three-dimensional, and cutting out some details. I don’t really know what that cavity near the beak tip is. I also compensated the shape of the nasoantorbital fenestra which seems to have some details still hidden behind the rock (the lacrimal fossa, perhaps).

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Then I glued the two halves together. Tomorrow I will continue and add intra-cranial details such as the palate, occipital bone and cavities.

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