A hidden camera planted in one of the most remote regions of the world has captured Dryas monkeys (Cercopithecus dryas), which was long thought to be extinct.

Researchers working on the Lukuru Foundation Tshuapa-Lomani-Lualaba (TL2) Project are the first to capture a rare video footage taken at the Lomami National Park in the Democratic Republic of Congo in Central Africa. They collaborated with experts from the Florida Atlantic University (FAU).

"This was an opportunity of a lifetime," said Daniel Alempijevic, who assisted in placing the camera traps, in a press release. "It was an incredible experience to work in the canopy of such a remote site, and to get the first camera-trap videos of an extremely rare and elusive species."

The camera traps in the area were set up after recent reports of a dead monkey by a local hunter in the national park.

Dryas monkeys are elusive cat-sized monkeys that are thought to live only in one part of the Congo basin, which is why the researchers were totally caught by surprise when they saw them in a different area. SciNews said they were first seen in 1932. Because of their small population and humans' uncontrolled hunting, they are thought to be extinct a long time ago.

"The Congo Basin rainforest is the second-largest rainforest in the world, and contains some of the least known species on the planet, many of which are threatened from hunting pressure and deforestation," said Kate Detwiler, Ph.D., a primatologist and one of those who worked on the footage. "Our goal is to document where new Dryas populations live and develop effective methods to monitor population size over time to ensure their protection. Understanding where they reside is important, because the animals living inside the Lomami National Park are protected, as it is illegal to hunt."

Fewer than 200 Dryas monkeys are believed to survive in the wild today. The cameras also caught bonobos, African palm civets and pottos.