Considering that we humans are particularly obsessed with mammals, and study them more than other creatures, we like to think we know a lot about them. We like to think we know what's out there. There hasn't been a new carnivore identifed in the west in 35 years. The papers are calling him a carnivore even though he's really more of an omnivore--he eats fruit and insects, too. Olinguito lives in the cloud forests of Ecuador and Colombia, and who knows where else.
It turns out, we probably had them in zoos in the US in the 60-70's, but mistook them for olingas, and didn't understand why they didn't breed. (For the biology-impaired, a species can only breed with itself and not with other species.) Olinguito was discovered by US scientists at the Smithsonian because they were looking through old bones and found some that didn't fit any known categories. Old bones CAN yield new information.