Stegosaurids are one of the most famous groups of dinosaurs of the Mid Jurassic to Late Cretaceous periods. These four-legged herbivorous dinosaurs were 10-30ft in length, and their widespread remains have been found in North America. Europe, Africa, and Asia. Stegosaurids had a single row or two rows of plates or spikes running down their backs. These dinosaurs probably ate low vegetation and cropped the plants with their beak-like jaws and weak teeth. The function of the back plates is not known ­ they may have been for sexual attraction, to guard against predators or they may have functioned as temperature control devices like the skin sail of Dimetrodon.

Stegosaurids had tiny brains ­ the largest was about the size of a golf ball. Species included Stegosaurus and Kentrosaurus which both lived in the Late Jurassic period, as well as Dravidosaurus, a species which was found in what is now India up to the end of the Cretaceous period.

Stegosaurus means 'roofed' or 'plated' lizard'. Remains of this Late Jurassic dinosaur have been found in Colorado, Oklahoma, Utah and Wyoming, USA. At 30ft long it was the largest known plated dinosaur, a four-legged herbivore with a small head and a toothless beak. The front legs were much shorter than the back legs. Stegosaurus also had one or two rows of tall bony plates jutting up from its neck, back, and tail. The tail was long and heavy, and was armored with four 1ft long spikes.

Kentrosaurus means 'spiked lizard', referring to the spikes on its shoulders and back. This herbivore was a Late Jurassic stegosaurid whose remains were found at Tendaguru, Tanzania. It was about 17ft long and had a double row of plates above the neck and shoulders, and pairs of spikes above its back and tail.

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