ATLANTA (AP) — Atlanta's zoo is mourning the death of its oldest gorilla.

Zoo Atlanta says 58-year-old Shamba, a western lowland gorilla, was found unresponsive Friday. A preliminary examination revealed advanced age-related complications, and the zoo's veterinary staff decided the best option was to euthanize her.

The zoo says Shamba was one of the oldest gorillas in the world. Western lowland gorillas are considered geriatric after about age 35.

More than 30 of Shamba's descendants — including grandchildren, great-grandchildren and great-great-grandchildren — live at Zoo Atlanta and other zoos around the U.S.

A necropsy is planned, with results available in several weeks.