As for Piltdown, that was a hoax perpetrated on British anthropologists by someone intimately familiar with them and their theories. Piltdown was widely ignored by almost all but a small bunch of British researchers--the hoax had been designed to catch them. Some researchers working in other areas recognized early on that Piltdown didn't fit. Friedrichs and Weidenreich had both, by about 1932, published their research suggesting the lower jaws and molars were that of an orang (they were correct). In fact, Piltdown was largely ignored from the mid-1920s, when the South African finds started coming because it simply did not fit.
It may amuse you to know that Charles Dawson reported having seen a sea serpent from a ship in the English Channel on Good Friday 1906 (J.E. Walsh, 'Unravelling Piltdown', The Softback Preview, (1997), p. 195-6). Nobody believed him at the time, and even creationists who believe in living plesiosaurs have been curiously unwilling to use this supposed sighting as evidence. Still, it may shed some light on Dawson's character, and on the origins of the Piltdown hoax.
Edited by Adminnemooseus, : Do quote box code.