Tupuxuara’s chest is protected by a big solid flat bone called the sternum, or stern. The stern will connect to the vertebrae through the scapula-coracoid bone and the ribs. Since it is practically flat, I started out drawing one of the sides on a 5mm sheet of XPS foam.
It is flat, but slightly rounded. It has a deep cavity on the inside near the front, and the tip is slightly rounded. I had to infer all this from the shadows of the fossil, since I only have a photo of each side. There are no side, front or back views. But I looked at some models and other pterosaurs and I think it’s a reasonable stern. So I twisted and folded the foam into shape, and glued some layers to keep everything in place.
When dry, I used a lighter to burn the foam a bit, add texture and smooth the edges. I think I did it too much, since the stern is slightly smaller than it should be. But I can fix that later. This is a view of the inside.
And this is a view from the outside of the stern.
I finished it with a layer of acrylic resin (modelling paste), some sandpaper and later, when dry, stained with coffee. Here is the result.
Those are the views I can compare to the pictures of the fossil. These are the views I did not have of the fossil, so I had to infer. I hope they are not too different from the real bone.
As usual, I can always change something. I probably will review all these bones when I connect them. The stern will connect to the coracoid and ribs, so I might change something when I test the connections.