Elly, the oldest black rhino in North America, has passed away, according to SFist. She was a longtime fixture at the San Francisco Zoo, where she recently underwent surgery for leg pain.

According to the local CBS affiliate, the surgeons determined that they would not be able to alleviate her pain enough for her to maintain a decent quality of life, and they decided not to wake her up from the May 3 surgery.

She was unusually old for a black rhino, a species that usually lives 30 to 40 years in the wild. The oldest black rhino on record lived to the age of 49.

Elly arrived at the San Francisco Zoo in 1974 and quickly became one of its most successful breeders, helping keep her critically endangered species alive. She had 14 calves, 15 grand-calves, and even a single great-great grand-calf.

There are currently an estimated 5000 black rhinos in the wild, up from 2475 in 1993. Black rhinos used to have the largest populations of any rhino species in the world.

[h/t SFist ]