Patti — a river hippopotamus and a favorite animal at the Milwaukee County Zoo since she arrived in 1972 — has died. Patti was humanely euthanized on Sunday, Nov. 10. According to a statement from the zoo,

The Milwaukee County Zoo has announced that longtime resident Patti, a river hippopotamus, was humanely euthanized on Sunday, Nov. 10.

Patti, the oldest hippopotamus in U.S. zoos accredited by the Association of Zoos and Aquariums, died Nov. 10, at the Milwaukee County Zoo. She was 55. Born at the Dallas Zoo, Patti arrived in Milwaukee in 1972 and lived there for more than 50 years.

Patti, the oldest hippo in U.S. zoos, has died at 55 at Milwaukee County Zoo. Her legacy includes contributions to wildlife research.