5. The Mount Owen Moa.
In the 1980s a group of researchers descended into the caves of Mount Owen in New Zealand. While exploring, they happened upon a pile of bones and a large claw. The remains were so well-preserved that they were unsure of how recent the remains were. In the end it was discovered to be a 3000-year-old claw of an upland moa, a flightless bird that is now extinct.