When Pirates of the Caribbean opened at Disneyland in 1967, all of the skeletons on the attraction were actual human bones.
The technology at the time wasn’t sophisticated enough to make skeletons that the company felt met their standards of realism. Instead of faking it, the Imagineers went to find the real thing at UCLA’s Medical Center.
Today, Disneyland says that there are no longer any human remains on the ride.