In trying to figure out why the Gobi Desert of Mongolia holds so many well preserved dinosaur fossils, paleontologists usually relied on their own experience. Now geologists have taken a closer look and come up with a different explanation. Their detailed examination of Gobi sandstones has produced striking evidence that the dinosaurs and other ancient creatures at a major fossil site were more likely killed and buried not by sandstorms but by sudden avalanches of water soaked sand.