Saola

The saola, Vu Quang ox or Asian unicorn, also, infrequently, Vu Quang bovid (Pseudoryx nghetinhensis), one of the world's rarest mammals, is a forest-dwelling bovine found only in the Annamite Range of Vietnam and Laos. The species was defined following a discovery of remains in 1992 in Vu Quang Nature Reserve by a joint survey of the Ministry of Forestry and the World Wide Fund for Nature. The team found three skulls with unusual long straight horns kept in hunters' houses. In their article, the team proposed "a three month survey to observe the living animal" but, more than 20 years later, there is still no reported sighting of a saola in the wild by a scientist.