Labels:text | font | paper | document OCR: An ornithopod ("bird-footed" dinosaur) little longer than a human, Hypsilophodon ("high ridge tooth") was a gazelle-like dinosaur, superbly engineered for both browsing and escaping danger. In its small head were large, keen eyes and a complex feeding mechanism: a horny beak with upper teeth; self-sharpening top and bottom cheek teeth that formed a cutting edge; strong, mobile jaws; and cheek pouches for storing food. Hypsilophodon's short arms ended in five stubby digits tipped with strong claws. Its sprinter's hindlimbs featured elongated shins and tall upper foot bones supported by three forward-facing, sharp-clawed toes. POWERFUL JAWS Hypsilophodon nibbled low-growing plants among the lush fern and horsetail meadows that lay between the rivers, lakes, and swamps of the coastal floodplain that covered much of southern England 120 million years ago. The creature nipped off fronds with its beak, stuffed them in roomy cheek pouches, and then pulped them with a powerful chewing action. Each time it closed its jaws, the upper jaws splayed out, but the lower jaws moved in, so that, as the jaws met, the top and bottom teeth obliquely sheared past one another. Chewing leaves eventually wore down even Hypsilophodon's high-crowned cheek teeth, but new teeth grew to take their place. HERD INSTINCT Timid Hypsilophodon's survival probably depended on group living. Since 1849, the remains of about 24 Hypsilophodon have been discovered in the Isle of Wight off the coast of England. Some specimens lay close together, perhaps part of a herd trapped in prehistoric coastal quicksand. While most members of the herd were apparently eating with their heads down, a few could have been scanning the area for danger, just as in a herd of modern antelope. TOP SPEED Running away was the defenseless creatures' only option when attacked by hungry carnivores (flesh-eaters). Hypsilophodon was one of the fastest dinosaurs of all. At top speed it could also dodge from side to side to evade a pursuer. Its long, tendon-stiffened tail helped it keep its balance when running and maneuvering at speed. Without a few seconds' warning, however, even Hypsilophodon could not have escaped the big, swift theropods ("beast-footed" dinosaurs) whose bones are also found on the Isle of Wight.
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