Stegosaurus was the largest of the stegosaur group. Its fossils were found mainly in present-day Colorado, Utah, and Wyoming.
Like most of its group, Stegosaurus lived toward the end of the Jurassic period, about 150 mya.
Stegosaurus was about 25-30 feet long from nose to tail and probably weighed more than 2 tons.
Its most striking feature was the row of large, roughly triangular bony plates along its back.
The name Stegosaurus means "roof reptile". This is because it was first thought that its bony plates lay flat on its back, overlapping like the tiles on a roof.
It is now thought that the back plates stood upright in two long rows.
The plates may have been for body temperature control, allowing the dinosaur to warm up quickly if it stood side-on to the sun's rays.
The back plates may have been covered with brightly colored skin, possibly to intimidate enemies--they were to flimsy for protection.
Armed with four large spikes, Stegosaurus probably used its tail for swinging at enemies in self-defense.