A park spokeswoman says two climbers were 7,500 feet up when the lead climber fell.
Officials from Yosemite National Park released pictures of the rescue. The spokeswoman says a safety rope wrapped around the man's right thumb and severed it from his hand. The severed thumb fell onto a ledge, where the man's climbing partner caught it.
The climber was rushed to a San Francisco hospital where surgeons were able to reattach the thumb.