Labels:text | paper | font | document OCR: Iguanodon ("iguana tooth") was a large, heavy ornithopod ("bird-footed" dinosaur) that existed in large numbers during the Cretaceous Period (144-65 million years ago). This dinosaur owes its name to high-ridged cheek teeth, similar to those of a modern iguana lizard, but much larger. Iguanodon cropped vegetation with its horny beak and chewed with its cheek teeth, with an unusual sliding action of the jaws. The wrist could rotate, and the five-fingered hands were unique and highly specialized. Each had a spiked thumb, which was unable to bend, three middle fingers with hooflike claws, and a grasping fifth finger that could be pulled in toward the palm. STRONG ARMS I guanodon was probably a peaceful herbivore (plant-eater) capable of standing and walking either on its hindlimbs or on all fours. Young animals, with their relatively short arms, were probably usually two-legged. However, adults had longer, stronger arms and could have lowered the forward part of the body to rest on the three weight-bearing middle fingers of each hand, possibly to drink or to browse on low-growing horsetails. A few trackways suggest that adults sometimes walked on all fours too. Yet most fossil tracks attributed to Iguanodon show only prints left by its big, three-toed feet. SPIKED THUMBS I guanodon could stand on its long, muscular hind legs to reach tree leaves. When walking on its hindlimbs, it would have thrust its head forward, holding its back and tail stiff and nearly horizontal. Iguanodon could have escaped from large predators such as Baryonyx by running on two legs. If cornered, however, the ornithischian ("bird-hipped" dinosaur) could have defended itself by jabbing out with its spiked thumbs. It is unlikely that any carnivore (flesh-eater) would have dared tackle a whole group of Iguanodon, and quite likely this dinosaur did roam the land in herds. One clue is a group of fossil carcasses found close together at a site in Germany. Scientists suspect that a large herd was engulfed and drowned in a flash flood before it had a chance to escape.
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