Polacanthus Reconstruction: Part 7 ‘Dorsal Spines’

I visited Dinosaur Isle Museum at Sandown on the Isle of Wight and whilst I was there I saw one of the Dorling Kindersley dinosaur models in the lab.

The Gastonia model has an original arrangement of spines.

The tall lateral (side) spines near the shoulders are quite striking compared with other reconstructions.

The model demonstrates the side row of spines from neck to the tip of the tail that formed Gastonia’s primary defense against predators.

The tail of Gastonia would have been a formidable weapon against medium to large theropods. Similar in effect to an Aztec Macuahuitl, the keratin covered tail spines would have probably caused significant lacerations to the lower body of any dinosaur unfortunate enough to be in the way of the swinging tail.

Suitable inspired, I returned to the Dinosaur Expeditions Centre at the Dinosaur Farm and decided to focus on producing a pair of dorsal (top) spines, notable for having a solid base.

I marked out the template on the foam with the keratin thickness outline added and started carving the shape out.

Once the first spine was finished I temporarily mounted it on the Minmi model to check how it looked.

I still need to blend the spine to match the body but the overall effect is imposing. So I repeated the process to make the opposite spine.

Next time I will sculpt a pair of Polacanthus spines based on a rare fossil.

Polacanthus Reconstruction: Part 6 'Cervical Spines'

With the first pair of Cervical (neck) spines done, I decided to base the next pair of (slightly bigger than half scale spines) on a plaster cast of a fossil Polacanthus spine rather than some small black and white photographs.

With the outline of the template marked out on the foam, I cut out one of the spines and started carving. A couple of hours later I had finished the left spine.

Before starting the opposite spine I thought it would be a good idea to mount the spine on the Minimi model to see how it looks. I temporarily attached the foam spine to the fibreglass model with a small piece of modelling putty

So far so good. Next I added the first cervical (neck) spine to check the effect of both spines together.

Obviously to finish the model they will need to be blended to fit when finally mounting them but the overall impression seems great.

An hour later I had carved the opposite spine.

So I mounted the pair of spines on the model.

Not too bad for a few hours work! Next I will look at a reconstruction of the Polacanthid Gastonia and sculpt a pair of  ‘solid-based’ scapula-coracoid spines.

Polacanthus Reconstruction: Part 5 ‘First Blood….’

With everything to hand I was finally in a position to actually do something. Before putting scalpel to foam I needed to create some templates to base the sculpted spines on.

The Minmi model is approximately half the size of an adult Polacanthus. Assuming the spines discovered to date are from adults (which is quite likely) then I would need to scale the spine to half actual size.

However there was another aspect to this reconstruction. The spines would be fine in their original condition for a skeletal reconstruction. However this was going to be a life-like, fleshed reconstruction. In life the spines would have been covered in keratin, like a crocodile scute.

So the spines would actually need to be slightly bigger than half size to take into account the keratin surface. With this in mind I selected the pre-sacral (neck to hip) spines images and set about drawing slightly bigger than half scale outlines.

Once left and right Cervical Spine templates were cut out I drew their outlines on the foam. (Note the ‘keel’ on the bottom of Spine 1 below was deliberately omitted on the foam as it would be embedded in the skin in life and would not be visible on the finished model).

I selected the first Spine and cut around the outline.

A few hours later I had sculpted both Left and Right Spines, but not before the scalpel blade caught the tip of my left index finger!!! So after a quick rumage through my first aid kit for a plaster, I donned a latex glove and a rubber glove to finish the sculpts.

With the light level dropping I decide to call it a day. My sacrifice had not been in vain!