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A dinosaurs` graveyard found in a remote region of northern China is being hailed as the richest source of fossils in the world. Remains of primitive birds, mammals, insects, plants and dinosaurs have been discovered, apparently frozen at a moment about 135 million years ago when a sudden catastrophe, perhaps a volcanic eruption, wiped them out. Among the most exciting fossils are more than 200 of a primitive bird and several specimens of a chicken–sized dinosaur, one with an egg still in its body waiting to be laid. Chinese paleontologists suggest that it may be the first true bird.