Lincoln Park chimp Keo dies
Keo, the 55-year-old Lincoln Park Zoo chimpanzee, was euthanized on September 30. Keo was suffering from advanced cardiac disease, according to zoo staff. Keo was the oldest living male chimpanzee in any North American zoo, and the very first chimpanzee to live at Lincoln Park Zoo.
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Keo was 55 when he died on September 30, 2013.