Seashells on tops of mountains.

Piltdown man was a fraud perpetuated upon the scientific community, one which that community eventually uncovered as the growing evidence made the possibility of fraud increasingly difficult to ignore. Even in the early years after its "discovery" when its validity was not in question, Piltdown was an anomaly that had little impact on scientific theories of human origins, and as time went by it was increasingly marginalized as fraud increasingly became the only realistic explanation.If you want an example of science radically changing theory you should look to continental drift. Read up on Eugene Wegener over at Wikipedia, it's a great story. Briefly, Wegener stood up to a geological community that largely rejected his ideas about continental motion about the earth's surface. He was eventually shown right, posthumously, unfortunately.Another example of radical change to theory would be what we today call the Copernican revolution, the discovery by Copernicus and the eventual acceptance by the rest of the world that the Earth does not lie at the center of the universe.But revolution and refinement of scientific theory are both driven by evidence. That's what makes the process of developing theories scientific. Theories are not accepted because scientists say so. Theories are accepted because the evidence is of sufficient volume and quality to persuade the community of scientists.The argument, "You've been wrong before and could be wrong again," is one that can be applied by all sides in all discussions and so has no validity. The accusation, "You could be wrong," just draws the retort, "So could you," and then what?