M'Dundamella, the eldest of the elephants at the Oakland Zoo and a resident there since 1993, collapsed inside her 6.5-acre habitat and was pronounced dead Tuesday afternoon of unknown causes. She had just turned 50 years old in September.

The zoo reported the news on Facebook, saying that M’Dunda was the third oldest African elephant in captivity in an Association of Zoos and Aquariums-accredited facility. Her collapse happened around 2:45 p.m. Tuesday, and when zoo veterinarians reached her, she was already deceased.

"M’Dunda has been part of our Oakland Zoo family for 26 years. She was such a gentle being, and closely bonded with her keepers. We’ll miss her greatly," says said Dr. Joel Parrott, president and CEO of the zoo, in a statement.

M'Dunda was born in Zimbabwe, as the zoo notes on its website, "in (or around) 1969." Her first home in this country was the San Diego Zoo. She was known to occasionally spar and sometimes nuzzle and "trunk twirl" with a 25-year-old male named Osh, who came to the zoo as a 10-year-old adolescent in 2004.

As SFGate notes, M'Dunda had far outlived most of her peers in captivity, with the average lifespan of elephants in captivity being only 17 years — compared to 56 years in the wild.

At her 50th birthday celebration three months ago, the zoo gave her some of her favorite foods, which included a "cake" made out of watermelon.

Her cause of death, while unknown, will be investigated in a necropsy at UC Davis.

Top photo by Steve Goodall