Mike Hale tells KNXV-TV he bought it recently at a sale in north Phoenix.
Shortly after the story was on television, police showed up at Hale's home, seized the skull and took it to the medical examiner's office.
Hale says he bought it for $1 and listed it for sale for $300.
Before the skull was seized, Hale says he'd received about 20 inquiries from people interested in purchasing it.