Drawing animals and having them turn out like anything other than an animal can be very frustrating. The legs are so straight and stiff it just looks wrong. The paws are nearly non-existent. The body looks sickly and the neck is long enough to make it a dinosaur. The head is too small to fit a brain and has too long of a nuzzle. Not to mention the tail — it's so big it looks like the heaviest part of the body. Even though you see and know all of this, you just don't know how else to draw this creature.
If you are determined, you may have already checked out some drawing tutorials and books on how to create life-like illustrations. You copy the designs and even try to follow their instructions of drawing circles and connecting them with lines. But when you try it on your own, without looking to anything for reference, even with the methods you saw in the books, it still doesn't turn out right and it still feels like something is missing.
There is something very important you've been missing and you've probably skipped past it in your drawing guides. The most important detail to drawing animals is shapes and understanding the creature's anatomy. Bones and muscles are essential to drawing anything that moves. If you have the bones and muscles in mind, you will be able to proportionyour animals with ease which will make your drawings more life-like.
Drawing an animal's shape is similar to that of a robot. Use the bones as the frame of a machine and the muscles as the equipment needed to make the frame move. Getting a picture of the anatomy of the animal and studying it is highly recommended and will greatly help. While studying, look at the muscle groupings and notice the shapes. Notice how the shoulders tend to have an oval kind of shape? Look at the bones of the hind legs. See how the bones connect to each other in straight lines, allowing it to stand? Take a look at the skull and jaw bone. Study the muscles that make the jaw move. Use the bones as guidelines and the inner frame. Envision the muscle needed to make that frame move. Use the muscles to move, position, and hold that frame up right, just how you want it. Envision the animal moving and how each part works. How the legs lift, how the neck lowers itself, how the head moves, how the tail moves to balance the creature.
When drawing, though, you don't have to draw every little detail. You don't have to draw the entire skeleton and you don't have to draw every fiber of muscle. What you need to keep in mind is the shapes. When drawing the forehead, picture the hard bone of the skull right under it. Draw a circle for the jaw muscles needed to make the jaw open and close. Study the anatomy, the shapes of the muscle groups, and envision how each part moves and soon you'll be able to see it in your mind's eye next time you draw. Once you are able to do that, your art will greatly improve and your drawings will be more life-like.