Horry County Coroner Robert Edge said the bones, discovered Saturday, had been determined to be male, the (Myrtle Beach) Sun News reported.
The bones were found in an area being searched for any sign of Heather Elvis, 20, who has not been seen since Dec. 17. Elvis' car was discovered two days later parked at a boat landing.
Another woman, Jamie Lynn Cross, 24, was reported missing on Christmas Day, two days after she was last seen. Her brother said she had gone out to dinner with a man and he last saw her getting into the man's car.
Investigators do not believe the two disappearances are related. A third woman with medical problems was reported missing Monday after she walked away from a caretaker's home but turned up Tuesday.
Edge said the bones that were found Saturday had been scattered, possibly by animals, and included hip bones and some long bones as well as the skull. He said they appeared to have been there for several years.
Investigators believed at first the bones might be those of Brittanee Drexel, who was 17 when she disappeared in Myrtle Beach in 2009. Brittanee had come to the resort for spring break after telling her mother she was visiting friends near their home in Rochester, N.Y.
But Edge said the bones are definitely male.