type of dinosaur, 1892, from Modern Latin order name Stegosauria (O.C. Marsh, 1877), from comb. form of Greek stegos "roof" (from stege "covering," stegein "to cover," from PIE root *(s)teg- "cover," especially "cover with a roof" (cf. Sanskrit sthag- "cover, conceal, hide;" Latin tegere "to cover;" Lithuanian stegti "roof;" Old Norse þekja, Old English þeccan "thatch;" Dutch dekken, German decken "to cover, put under roof;" Irish tuigiur "cover," tech "house;" Welsh toi "thatch, roof," ty "house") + -saurus. The back-armor plates in the fossilized remains look like roof tiles.
one of the various plated dinosaurs (Stegosauria) of the Late Jurassic Period (159 million to 144 million years ago) recognizable by its spiked tail and series of large triangular bony plates along the back. Stegosaurus usually grew to a length of about 6.5 metres (21 feet), but some reached 9 metres (30 feet). The skull and brain were very small for such a large animal. The forelimbs were much shorter than the hind limbs, which gave the back a characteristically arched appearance. The feet were short and broad.