International union for conservation of nature
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.”
“It’s a message of hope and opportunity," one project leader said.
"It’s just an amazing sequence of events.”
More than 60,000 species are currently living. Many of them are in trouble, according to the world's first global trees database.
Slaughtering orangutans is a common crime on Borneo, but rarely prosecuted.
A new global analysis finds nearly half of threatened mammals are at risk, up from just 7 percent.