The so-called "Piltdown Man" consists of fragments of a skull and jawbone collected in 1912 from a gravel pit at Piltdown, a village near Uckfield, East Sussex. The fragments were claimed by experts of the day to be the fossilized remains of a hitherto unknown form of early human. The Latin name Eoanthropus dawsoni ("Dawson's dawn-man") was given to the specimen.

The significance of the specimen remained the subject of controversy until it was exposed in 1953 as a forgery, consisting of the lower jawbone of an orangutan combined with the skull of a fully developed, modern man. It has been suggested that the forgery was the work of the person said to be its finder, Charles Dawson, after whom it was named. This view is strongly disputed and many other candidates have been proposed as the true creators of the forgery.

The Piltdown hoax is perhaps the most famous archaeological hoax in history, with its prominence lasting over forty years. Its bearing on science is strong because of two factors, namely the weight of the link between humans and apes and second due to the duration of which it was a part of scientific “fact.”

http://en.wikipedia.org/wiki/Piltdown_Man 

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