Scientists discovered a new mammal. Hear its haunting bark.

On our wildly diverse planet, scientists are still finding new species. Even mammals.

While on an expedition in Nigeria in 2009, researchers noticed a curious bark-like call in the night. It turns out the source was a creature new to science, a species of tree hyrax — small, herbivorous mammals — called Dendrohyrax interfluvialis.

It's not easy to confirm a new species, especially when it comes to an elusive, nocturnal, forest-dwelling animal in a remote region. The scientists announced a description of the novel species on Monday.

(In the video, the "shriek" sound of another hyrax species is played first, which contrasts with the "bark" of the newly described species, played second.)

That bark-like call played a prominent role in identifying the new mammal. "Sometimes a keen ear is as important as a sharp eye," Yale anthropologist Eric Sargis, an author of the research, said in a statement.