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Dinosaur is the name of large extinct reptiles of the Mesozoic Era, during which they were the dominant land animals on Earth. The term was proposed as a formal zoologic name in 1842 by the British anatomist Sir Richard Owen, in reference to large fossil bones un ....

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.... identifications are in dispute. They ranged in weight from 4 to 6 lb., in the case of the compsognathus, and up to 160,000 lb., in the case of the brachiosaurus. Most dinosaurs were large, weighing more than 1,100 lb., and few weighed less than 100 lb. Most were herbivores, but some saurischians were carnivorous. The majority were four- footed but some ornithischians and all carnivores walked on their hind legs. Always classified as reptiles, dinosaurs have traditionally been assumed to have been reptilian in their physiology, cold-blooded, and ectothermic. In recent years several different lines of evidence have been interpreted as indicating t ....