Subject: Are there any extinct chimpanzee species? Or just two known?

hi, my name is steve and I am interested in primates, since the human 
is one. I have a question for you.

Are there any known extinct species of chimpanzees or is it just two
known species of chimps, the common and the pymgy chimp, that have 
remained invariant for over 6 million years since the split of the the 
common ancestor of chimps and humans.

Re: Are there any extinct chimpanzee species? Or just two known?