What is a Stegosaurus?

Stegosaurus was a 30 foot long, four legged, herbivorous dinosaur that lived in North America around 150 million years ago. They had bulky bodies, short forelimbs, and large hindlimbs. The head was small, and its neck hung low to the ground. They are most famous for the triangular plates that protruded from either side of the spine, and the four spikes at the end of its tail, which were used for self defense.