Stegosaurus is famous for the plates that form an alternating row from the neck to the tail. Various hypotheses have been proposed for their function: from defensive armour, thermoregulation (warming / cooling) to visual displays. Their exact function is still open for debate although current research by the Natural History Museum in London on Sophie the juvenile Stegosaurus may well conclude that all three proposals are correct. Just as feathers can be used for insulation, display and flight!
Polacanthus and it’s relatives had a diverse range of dermal osteoderms (bony armour). The ‘Splate’ or Spined-Plate is a flat plate like spine with a prominent spike in the middle. 'Splates’ have been found from Polacanthus and Hoplitosaurus. Their exact postion on the body however is a matter of debate (Shoulders, Back, Hip or Tail?) subject to future discovery of an articulated skeleton with a splate to confirm their actual placement.
Sadly I don’t have an actual fossil 'Splate’ or plaster cast so I had to base the sculpt on some line drawings and photographs with a scale bar!
Once I had a scaled drawing I traced a copy to make a template and copied this on to the Extruded Polystyrene Foam.
With the templates marked out I cut the shapes out of the blue foam and started to sculpt the first 'Splate’.
Given the narrowness of the prominent spine I took my time to sculpt the 'Splate’.
I repeated the process for the opposite spine.
With the pair of 'Splates’ finished, my next task will be to sculpt the numerous middle to late caudal tail spines for the Polacanthus model.