Piltdown Man

 was a skull created by the First Doctor from parts of a human cranium and filed-down ape jawbone in 1912. For forty years, it was considered by Earth scientists to be a missing evolutionary link between apes and humans, until the forgery was discovered. The Doctor created this skull to replace an alien skull found in a quarry near Piltdown by Charles Dawson. The Doctor knew that Dawson presented a "missing link" to the scientific community at this time and knew that later, after Dawson's death, it would be found to be a forgery. Thus, this is another example of a bootstrap paradox. (AUDIO: The Suffering)