One of the world's oldest chimps, Fifi, has died in Australia, zoo officials said Friday.

Fifi was the matriarch of the 18 chimpanzees at Sydney's Taronga Zoo, and celebrated her 60th birthday in May with sugar-free cupcakes and coconuts among four generations of her family.

But Fifi, who suffered arthritis and had taken to sipping from a cup of chamomile tea each morning in her later years, stayed in bed Thursday morning, raising suspicions among the keepers that she was unwell, the zoo said in a statement.

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Keepers provided her with fresh bedding and her favorite foods, while other chimps in the group visited her throughout the day, the zoo said. She died peacefully in the afternoon.

"Keepers have been saddened by the peaceful passing of their oldest and much loved Chimpanzee, Fifi," the zoo said.

The zoo said an investigation would be held to determine a cause of death.

Chimps, who share 98 percent of humans' DNA and are our closest living relatives in nature, have an average life expectancy of about 45 years, but can live longer in captivity because of the health care and good diet they get.

Cheeta, the star of a dozen "Tarzan" movies in the 1930s and 1940s, is listed by the Guinness Book of World Records as the world's oldest chimp. He turned 75 in April.