The Roofed Lizard
The name Stegosaurus means ‘roofed lizard”. This dinosaur lived around 156-140 million years ago, during the Jurassic Period, in regions where the climate was warm and moist and the sea levels were high. Its habitat included vast flooded areas, temperate and subtropical forests, and coral reefs. The Stegosaurus had 17 bony plates that were embedded in its back. The plates ran along the Stegosaurus' back and tail, in two rows and were useful in regulating the body temperature. They were also used for protection. The Stegosaurus had spikes at the end of its flexible tail, that were used as weapons too, and the spiked tail was called a "thagomizer."
Although Stegosaurus was about the size of a bus, it had a small head –around the size of a horse's head- and a brain that was only the size of a walnut. It ate only plants like ferns, horsetails, mosses and bushy conifers. The Stegosaurus also swallowed small rocks - known as gastroliths - that helped mash the tough vegetable matter in its enormous stomach. Of course, it's also possible that Stegosaurus swallowed rocks because it had a brain the size of walnut! Unlike most dinosaurs, the Stegosarus had cheeks that allowed it to chew and pre-digest its food, and also allowed it to store more food than non-cheeked dinosaurs.
Mass extinction of dinosaurs occurred toward the end of the Jurassic period. During this extinction, most of the stegosaurus dinosaurs died out...no one knows exactly why.