Stegosaurus-150 million years ago, the large, heavy Stegosaurus inhabited the earth. On his back he had large bone plates, on his powerful tail sat sharp spikes. The Stegosaurus was about the size of a coach - up to nine meters long and four meters high. For a long time he was considered the dumbest dinosaur because his brain barely grew bigger than a table tennis ball. It weighed only 80 grams at a body weight of 4.5 tons. Today, it is believed that it had some sort of second brain in its tail base, and although it was an herbivore feeding on low-growing ferns, its teeth were far too sharp to chew - resembling small saw blades - to feed the plants in its stomach crush, he swallowed stones.