Stegosaurus

By the Late Jurassic, the plant-eating dinosaur clans had expanded into a dozen families. Stegosaurs are famous for their tiny brains-one 30th the size of an elephant’s of the same weight and 10 times smaller than the meat-eating allosaur’s. However, what stegosaurs lacked in brains they made up in brawn. The muscular tail carried four sharp bone spikes, covered in life with an outer layer of horny skin. Tall joints let the stegosaur twist and curl its tail in almost any direction, and it could curve its torso and neck with ease. Stegosaurs also had a tighter turning circle than any other large plant-eater. On hard ground, they were skilled swordsmen, lunging and thrashing with their four-pointed lances. Although they were as heavy as elephants, stegosaurs had tiny feet with just three tiny toes. The foot area was only a third as big as that of other big herbivores like Triceratops and Denversaurus – an adaption to suit hard, firm ground.