International union for conservation of nature
A one-two punch of poaching and habitat loss threatens the creatures.
The "golden wonder" species had not been seen for more than four decades.
But don't even think about trying to keep one as a pet.
"They were so close and extremely calm and seemed not disturbed by our presence."
Primatologist Laura Marsh said she burst into tears when she first caught a glimpse of the Vanzolini bald-faced saki monkey in the Amazon.
The Philadelphia Zoo welcomed the new baby on Friday.
“We take care of the elephants, and the elephants are taking care of us.”