Category Archives: Pterosaur #2: Anhanguera

Anhanguera piscator, a Brazilian pterosaur

A new family member

The Imaginary Pterosaur family will soon have a new member: Tupandactylus imperator. Anhanguera’s body is also on the way. These are the skulls of the three imaginary pterosaurs so far (on a 1.00 x 1.20 m sheet of XPS foam):

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Anhanguera has also gained new front (rostrum) teeth (it looks a lot more like the fossil now), and brain cavities; I also improved the shape of the head and the eye cavities.

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Finished Anhanguera skull

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I finally finished the skull of Anhanguera piscator (well, almost… I still might sand it a bit, paint it, make the cervical spine connections and replace the front teeth with longer fangs, but it’s 99% done.) I lost track of how much time I invested into this, but I think it took me something around 30 hours of work, more than half of it working on small details (that means I can probably make a quick not-so-detailed skull in half that time). I used one sheet of a 65×40 cm XPS foam board, about 50g PVA (polyvinyl acetate) glue, 100 ml of modeling clay (acrylic resin), 8g of epoxi resin, 1 transparent plastic (PVC) hanger, cotton gauze.

These are its dimensions:

  • Length of the skull: 63.5 cm.
  • Maximum width (near the jaw articulation): 10 cm.
  • Minimum width (narrowest part of the beak): 3 cm.
  • Height (skull + mandible): 17 cm.
  • Height (skull without mandible): 14 cm.
  • Weight: 220 grams.

The pictures below show the skull from several angles.

Top, bottom, side

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Different angles

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Compare that last photo with this one, from the fossil of a real Anhanguera piscator (Source: Photo by Makoto Manabe published in David Hone’s Archosaur Musings):

My Anhanguera wore braces when young, that’s why it has no crooked or oversized teeth 🙂 (but I will definitely replace those front teeth with longer ones).

UPDATE

New rostrum teeth and improved eye cavities for Anhanguera:

photo

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Modeling the cavities in Anhanguera’s skull

There are many advantages in making the pterosaur out of foam. One of them is the weight. Guidraco’s full skeleton including the skull weighs little more than one kilo. The skull is the heaviest part because of the teeth and also because of the details where I use modeling paste. A light model reduces shipping costs and exhibition costs. I can safely hang a 1,5kg skeleton using thin fishing line and paper clips. I also decided not to coat the skeleton with resin. Not only would that at least double the weight (it would at least triple the weight of the body), but it would also require different (and certainly heavier) connections for the bones. I currently use pins and silicone rubber (clear caulk) for that, which I can remove after the exhibit.

To keep everything as light as possible, I try to make the bones hollow and use as little modeling clay as possible. I basically use it to fill small cracks. Larger areas are closed with pieces of foam. When it is difficult to model with foam, very thin layers of modeling clay can be applied using cotton gauze as a base. This is shown below.

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How to make pterosaur teeth from a plastic hanger

I described how I made the teeth and showed them already attached to the skull but I didn’t describe the details of the process yet. So here it is.

To start you need a candle, a lighter or matches, gloves, cutting pliers.  You also need transparent plastic hanger like this one:

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It should have a tubular structure and the tubes should be about 0.8cm in diameter. Try to get one that has no bubbles in the plastic or that has at least some long sections (more than 3cm) without any bubbles. Break it apart.

Choose a piece of the hanger which has no bubbles, turn it slowly over the candle and move it sideways (heat about 2 cm of plastic). Do that for a few seconds (10-15 seconds). Don’t let the flame touch the plastic. You should do this in a ventilated area (and use leather gloves to protect from the hot plastic).

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You will notice that after a few seconds the heated part will become brighter and translucid (with very small bubbles). You can move it away from the candle now, and it will continue to heat and become softer.

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When that happens, pull slowly, then stronger, until it starts to give in.

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Hold it over a curved surface to shape it if you wish (a tube with a diameter of 10cm if you are making curved pterosaur teeth). Wait for some 15 seconds and when it becomes solid you can let it go.

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Practice leaving the plastic under the flame for more or less time until you achieve the desired results. If it heats too much, when you pull it may get too thin or break. Try pulling slower. You can obtain different effects with the plastic pulling faster or slower, letting it go before solidifying, or heating more or less and even letting it break. Be careful to not burn the plastic. It gets black, unusable and the smoke is very toxic.

When solid, you can break the halfes apart, trim to the desired size, and you have two teeth.

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But the melted plastic doesn’t really look like teeth, does it? You have to carve it a bit using a knife as if you were sharpening a pencil until you have something in the shape of sharp teeth.

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The next step is to cut the teeth out. Not so easy. This kind of plastic is very hard and you won’t be able to cut it with regular pliers. You can use a hot knife or cutting pliers of the kind that cuts padlocks. I tried smaller ones but they would crack the plastic. Protect yourself cutting the plastic in a bag or box, since the parts may go flying out when split apart.

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That’s it. Now we have teeth.

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The last step is to attach the teeth with epoxi resin to the skull using a picture of the fossil as a guide.

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Anhanguera’s skull with teeth

I finally added a full set of teeth to the skull, which is almost done. Now I am going to separate the mandible so I can work on it, and then I’m done. This is the result so far.

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Adding detail to Anhanguera’s head

I didn’t have much time this weekend, so I just worked on details like the cavities of the skull. I compared several different fossil pictures (a privilege I did not have with Guidraco) and was able to come up with something which resembles most of the pictures. Of course, if you are a pterosaur skull expert, you will find several inaccuracies in the model, but I believe it has more detail than most of the models I saw. And if there is something terribly wrong, I can always tear it apart and fix it 🙂

These are some pictures showing details in the head. It is still not finished. I will later add some modeling clay and make the bones smoother.

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Anhanguera’s new teeth

I still need to make and attach some 30 teeth, but the most important ones are in place! This pterosaur has perfect teeth: it probably wore braces when young.

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