2. The Skull of Calaveras County
In 1866, while digging in a mine under volcanic deposits, miners in Calaveras County, California came across a human skull nestled 100 feet deep. Harvard University professor and California state geologist Josiah Whitney initially believed it could date back to the Pliocene age, which would make it over 5 million years old.
He was later proved wrong as news surfaced about local men playing Whitney for a fool.