Stegosaurus is the biggest known stegosaurid, with the largest plates. Hip were room-high; back legs were twice as long as front legs. Two rows of plates ran down neck and back. The largest plate was 30 inches high and 31 inches long. At least four heavy spikes flanked the tail.

Length: Up to 30 feet.
Weight: Up to 2 US tons
Time: Late Jurassic.
Place: North America (Colorado, Utah, Oklahoma, and Wyoming.