Labels:text | font | screenshot | paper OCR: Stegosaurus ("roof lizard") gets its name from the big bony plates that jutted upward from its neck, back, and upper tail. Until recently, scientists were unsure how its plates were arranged. Some believed that they were paired. Others thought that they alternated. A third group put them in one row, with big plates overlapping. In 1992, a newly discovered skeleton proved that the plates formed two staggered rows. A bony plate probably protected each hip, and two pairs of spikes stuck out sideways from the end of the tail. As heavy as a big rhinoceros and about the length of a bus, Stegosaurus is the largest known plated dinosaur. It stood more than room- high at the hips and walked on elephantine limbs. Its small head was held low and ended in a toothless, horn-covered beak. Behind the beak were numerous teeth. It is not known if the tail drooped or was held aloft. VEGETABLE BROWSER Fossil evidence suggests that Stegosaurus roamed wooded plains, browsing on low vegetation. However, an alternative theory claims that it was built to rear up and that it browsed at heights of up to 3.5 m (about 11 ft). The hindlimbs were longer than the forelimbs, and the plates on Stegosaurus' back could have provided for back muscles lifting the front part of the body. The supple tail was better suited for pressing against the ground than the rigid tails of most ornithischians ("bird-hipped" dinosaurs), and the tail and hindlimbs could have formed a tripod when a Stegosaurus reared up. Most paleontologists (scientists who study fossils) are, however, unconvinced by this theory. SELECTIVE FEEDER Ideas about Stegosaurus' diet have changed over the years. At first, it was thought that the animal had weak teeth and that it fed only on soft foods; today, however, this assumption is in some doubt. On the other hand, the narrow snout indicates that Stegosaurus may have been a selective feeder; and it may have picked out such choice items as seed-fern "fruits" and the fleshy "flowers" of cycadeoids (palmlike tropical plants). IMPRESSIVE BACK PLATES Stegosaurus' back plates probably helped soak up and shed heat, and rival males may have used them in harmless threat displays. There were no plates covering the flanks, but a Stegosaurus would have been able to fend off enemies by swishing its spiked tail, or backing into them like a porcupine. A discovery in 1992 revealed disk-shaped plates protecting the hips, and a pattern of disk-shaped bony studs that shielded the vulnerable throat.
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