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Long before human beings came to this world, dinosaurs were once kings on the earth．They were either meat-eaters or plant-eaters．Recently scientists found the longest dinosaur fossil in the world in Xinjiang．It is a 15-metre-long neck bone．Scientists think the bone is a part of a 35-metre-long Mamenxi Dinosaur．
Mamenxi Dinosaurs lived from 156 million to 145 million years ago．They had the longest neck of any known dinosaur．They ate plants．They used their 10-metre-long neck to reach high leaves．
Mamenxi Dinosaurs may have hatched from eggs．Scientists think the mothers laid their eggs as they walked．But they probably did not take care of their babies．If the babies survived, they lived for about 100 years．
T-rex lived about 85 million to 65 million years ago．Scientists found their fossil in tropical forests near rivers．This meat-eater had a huge head．It has tiny arms, each with two fingers．T-rex had a slim, hard, pointed tail．It helped them to balanced and make quick turns while running．
Not all dinosaurs were huge．There were plenty of small and medium-sized dinosaurs．The smallest dinosaur discovered was the size of a chicken．
There were no flying dinosaurs or swimming dinosaurs．All dinosaurs lived on the land．None of them lived in the sea or flew(before birds)．There were some flying and swimming animals then but they were closely related to dinosaurs．Some meat-eating dinosaurs developed feathers and became birds．
Dinosaurs lived on the earth for more than 150 million years, and then disappeared about 65 million years ago．Scientists try to explain their disappearance, but they've got more questions than answers．Dinosaurs are mysterious．Perhaps this is why people love them so much．
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