Kirk, a member of the Dallas Zoo's chimpanzee troop, died Friday of heart disease, the zoo said.
The 31-year-old chimp stopped breathing right before the primate zoologists' rounds at the end of the day. Life-saving measures were not successful, the zoo said.
A necropsy showed the chimp had heart disease, which is a major cause of death in great apes, but the zoo said he did not show any signs of heart-related illness or distress in the weeks leading up to his death.
Kirk came to the zoo in March 2018 with his mother, Margaret.
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The zoo said in a post to social media that Kirk was a "sweet chimp who loved to eat carrots and energetically gallop around the habitat."
His death comes months after the zoo's eldest chimp, Missy, died in February at 56.