(photo by Alexandra Reddy, Smithsonian’s National Zoo./This red-fronted lemur died last week at the National Zoo. He was named Red Oak, was 24 years old and was described as an endearing, charismatic animal. )

A long-lived lemur, who was named Red Oak and was said to have a big personality for a small animal, died Wednesday at the National Zoo.

The zoo said the red-fronted lemur went into cardiac arrest during a physical exam that was performed after he was found unresponsive during routine wellness checks.

Attempts to resuscitate him failed, and it was decided to euthanize him, zoo officials said. At 24, he was old for his species, they said.

Hunting and loss of habitat has made the red-fronted lemur a vulnerable animal, according to the zoo. It lives in the wild in deciduous woodland on the island of Madagascar. Fewer than 15 of them remain in zoos in North America, the Smithsonian said.

In a statement, the zoo quoted an assistant curator of primates, who called him an animal who made his presence known to the other two species of lemurs exhibited with him and his mate.

“There was never a question that Red Oak was in charge of the group,” said the curator, Becky Malinsky, who called his personality both “endearing and charismatic.”