A large, slow moving plant-eater, Stegosaurus would have defended itself from predators like Allosaurus with its powerful spiked tail. The bony plates along its back were embedded in the skin of the animal, not attached to its skeleton, which is why in most fossil finds the plates ...A large, slow moving plant-eater, Stegosaurus would have defended itself from predators like Allosaurus with its powerful spiked tail. The bony plates along its back were embedded in the skin of the animal, not attached to its skeleton, which is why in most fossil finds the plates are separated from the body.
The plates may have been used to warn off predators, or allowed members of the same species to recognise each other. Another suggestion is that the plates were used to regulate body temperature.