Here i'm further developing my facial anatomy knowledge by sculpting a skull of a gorilla. After sculpting the skull in ZBrush (approximately 1 hr), I began to design a gorilla facial concept over the skeleton (approximately 1 hr on facial design).
A tip for sculpting an animal skull in ZBrush is to work on 6 pieces of the skeleton skull separately.
Here's a picture of the 6 pieces I found helpful (eye socket, cranium, upper mouth, lower jaw, lower jaw piece, upper mouth piece):
A tip for teeth modeling in ZBrush is to sculpt some teeth then mirror in Y (subtool master mirror tool) to get a beginning for bottom teeth. Also using ZBrushe's auto group is extremely helpful for being able to adjust teeth individually. The clip curve brush was also very helpful (as i started with a polycube shape with rather sharp corners so using clip curve from bottom viewing the teeth could soften the hard corners).
Inspired by the amazing animal anatomy work of:
Ken Hultgren ("The Art of Animal Drawing")
Gyorgy Feher and Andras Szunyoghy ("Cyclopedia Anatomicae")
Eliot Goldfinger ("Animal Anatomy for Artists")