ONCE you understand the underlying structures of humans, and also understand that the underlying structures in animals are cut from a similar design pattern, it makes animal drawing a lot easier to demystify. When I was an art student one of my primary mentors Marshal Vandruff told me once you are reasonably comfortable with drawing people the secret to unlocking animals is to "pick a favorite". What Marshal was getting at is this: If you figure out how to draw horses, dogs, or cats well, you unlock the other animals as well since the are so very similar in structure!
SKULLS
Cats...way smarter than fish
Skeletons
Muscles
Legs
"Arms"
"Hands & "Feet""