Stegosaurus

Stegosaurus is a genus of armored dinosaur. They lived during the Late Jurassic period, some 155 to 150 million years ago in what is now the western United States and Portugal. Due to its distinctive tail spikes and plates, Stegosaurus is one of the most recognizable dinosaurs. Several species have been identified in the upper Morrison Formation, represented by the remains of about 80 individuals.

A large, heavily built, herbivorous quadruped, Stegosaurus had a distinctive and unusual posture, with a heavily rounded back, short fore limbs, head held low to the ground, and a stiffened tail held high in the air. Its array of plates and spikes has been the subject of much speculation. The spikes were most likely used for defense, while the plates have also been proposed as a defensive mechanism, as well as having display and thermoregulatory functions.

Stegosaurus had a relatively low brain-to-body mass ratio. It had a short neck and small head, meaning it most likely ate low-lying bushes and shrubs. It was the largest known of all the stegosaurians and, although roughly bus-sized, it nonetheless shared many anatomical features with other stegosaurids.