Charlie the beloved patriarch of the Oregon Zoo chimpanzee family passed away suddenly Thursday afternoon.

Senior primate keeper Dave Thomas said the 39-year-old, 160 pound chimp was expected to live another 20 years. Charlie survived the African bushmeat trade to become a pet donated to the zoo in May of 1972.

Slideshow: Charlie the chimp

“It’s the end of an era, and the zoo will never be the same,” Thomas said. “We have to go on though, to provide care and support for our remaining females: Delilah, Leah, Coco and Chloe.”

The four female chimps were surrounding Charlie as a volunteer saw him down. Thomas was the first staff person to respond and initiated an emeregency response system. Vets and other staff rushed to the chimp exhibit.

Several minutes passed before the female chimps could be moved safely away and by that time, Charlie was dead, Thomas said.

The females have since been placed together. Leah and Delilah went straight to where Charlied died, Thomas said. He thinks they will continue to look for him for several weeks, believing he might be alive.

Thomas said the primate staff will try and keep as regular a schedule as possible to help comfort them.

“The girls need to know that we are still here for them,” Thomas said.