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.
I cut the two halves, folded and molded a bit and then pasted them together. I also cut out the dorsal side.
After fitting all the parts, I filled the open ones with smaller bits of foam.
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.
I shaped the palate convexly to match the original fossil.
And attached it in place.
Pins aren’t enough to hold it in place while drying.
The occipital bones were attached after the palate was dry.
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.
I also used fire to shape the palate, the jaw hinge and the throat after the occipital bones were in place.
It’s practically finished. Now we need to add the details, which takes up most of the time.