Tupuxuara: the pelvis, sacrum and dorsal vertebrae

The specimen I have been using as a source (IMNH 1052, Iwaki Museum, Tokyo) has no pelvis, sacrum or any other dorsal vertebrae. I already made all the bones from that source. The sources I used for this pelvis were kindly sent to me by Mark Witton, and belong to a related species (possibly a Tupuxuara).

My sources were four views and a diagram from where I calculated the size of the pelvis relative to the other bones. The right view was the best, so I used it to sketch the pelvis bones. I sketched the sacrum from the dorsal view. There was also a posterior view, which I used later.

sketch

I cut the parts slightly larger so they could be molded.

cut

First, I assembled the sacrum gluing the two halves together (by the spinal crest).

assemble_sacrum

Then some trimming, and let it dry.

attach_sacrum

I was in a hurry to see what the pterosaur would look like with a pelvis, so I pinned the parts together and let the sacrum dry hanging on its “spinal chord”.

test

Then I added some foam to the other side, to shape the sacrum, and compared it to a diagram I made from the sources.

sacrum_1

While that was drying, I worked on the sacral and dorsal vertebrae, carving a spine from thick foam. Here I lined up the sixth thoracic vertebra (the last one from the notarium), three free lumbar (dorsal) vertebrae, and seven fused vertebrae.

dorsal_sacral

vertebra_sacral

I tested it before attaching the parts.

test_sacrum

I had no source for the three lumbar vertebrae, so I invented them based on the others.

dorsal_start

Here are the vertebrae lined up.

dorsal_test

And here is the first one that articulates with the pelvis in place.

dorsal_foam

As a spinal chord I am using plastic tubes of different widths. I insert the thin ones into the wide ones. There is a spinal chord for the cervicals, for the notarium and for the pelvis. The tail vertebra will be mounted on a thin rigid plastic spinal chord, which will be inserted in the thinner tube (the white one in the picture below).

sacrum_2

Time to attach the pelvis. First one side.

pelvis_side

Then the other. I always twist and fold the foam before attaching.

pelvis_both

Some parts need more work. Here I am trying to shape the pubis while keeping the ischium in place.

ischium

The two halves are not enough to provide all the three-dimensional details I need for the pelvis, so I made some “masks” with 5 mm foam which will allow some shaping.

masks

I also added some foam at the sides of the ilium to shape a small iliac crest (extending from each side of the sacrum). From the pictures I don’t know the exact shape of the ilium (I have no frontal view, and it’s partially damaged), so I looked at some other pterosaurs and chose something which matched the picture. This is the pelvis seen from the inside after most of the foam shaping.

front_foam

Another view.

sacrum_all

And here’s a dorsal view.

top_foam

Now the resin coating, coffee staining, and we’re done. Here are three views of the pelvis. This is the left side.

side

This is a dorsal view.

dorsal

And this is a ventral view.

ventral

The pelvis is a complex set of bones. I don’t know if I achieved in making an accurate one. I did my best with only three views. I’m not really sure if I should have closed the ischium. If I get more data in the future I will fix any mistakes.

Here you can see it in other angles.

ischium_done

angle_ventral

pubis_close

angle_ventral_2

dorsal_close

Now finally I can attach the legs. Here are two pictures of the pelvis in place with the femora attached.

connected

from behind

This is what it looks like when you are underneath a pterosaur skeleton.

under

It saw us and it’s coming this way!

almost done

What’s next? I don’t know. As you can see from the pictures above, some bones are connected with rubber bands: I still didn’t make any carpals. I will have to invent carpals, fingers, toes, and tails. I have none of them. They are small and simple bones, so there is a good chance that I might finish this skeleton tomorrow.

I already have some sources but I am still interested in any new ones. If I have more information I will be able to make a more accurate model. I am interested in pictures or drawings of feet, tails or hands of a Tupuxuara, Thalassodromidae, or even a related species. If you have any, send me an email!

1 Comment

Filed under Pterosaur #5: Tupuxuara

One response to “Tupuxuara: the pelvis, sacrum and dorsal vertebrae

  1. Pingback: Making of a Tupuxuara | The Imaginary Pterosaur

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