The Stegosaurus (bone-plate dinosaur) was a herbivore. It used its thorny tail as a defensive weapon. The large diamond-shaped bony plates on its back served to absorb and dissipate heat.
The bony plates of the Stegosaurus were covered with skin and had trough-like depressions on their surface that accommodated many blood vessels. Large quantities of blood were able to circulate through them. Inside the small skull of the Stegosaurus was a brain only the size of a walnut.

Length: 9 m
Weight: 2 t
Period: Upper Jurassic (150-136 mill. years)