Today is "Endangered Species Day" in case you did not know. It is one of those that are hard to keep track of because it isn't a specific date, instead it is on the 3rd Friday of May.
These monkeys are possibly the first primate to go extinct in hundreds of years. They have not been seen since 1978, or at least not officially. There were a couple sites that said there has been evidence that they still may have a small population in Côte d'Ivoire, but none mentioned what that evidence is. Unfortunately I have a feeling it might be some were found in the form of bushmeat. Humans hunting them has been their biggest threat and then habitat loss. They are not large and were only discovered in 1933. The man who is listed as having discovered them named them after a woman who was part of the group, named Miss Fanny Waldron.
Wikipedia said there are no pictures or video of them alive, and I certainly could not find any. I did find one picture that showed what I think was them dead, flat out on their face in a tray, so not any help to me. In order to do this picture I looked at the dead monkeys, the two older drawings I saw that that were hopefully at least slightly accurate as far as colouring, several skulls for the teeth especially (still not this monkey, but other colobus monkeys), and then a lot of other angry monkeys to try and get as close to what these might possibly look like. I don't usually like to paint animals that are so obviously upseet looking. My mood after the eye doctor visit yesterday and the thought that these could be the first primate in possibly 500 years to go extinct, I decided it was fine to paint a monkey that is really ticked off about something and not afraid to let it out! Or, maybe it looks as if it is yawning to you, and I am fine with that too. I already did paint a yawning Red-ruffed Lemur, but I was very careful not to show lots of teeth that time because I wanted to make it absolutely obvious it was not angry.