Every character and concept artist should study anatomy. Why? Because without a sound knowledge of anatomy, your creations will lack credibility. And if you are working in a creature pipeline, an understanding of the fundamentals is absolutely essential.
At the top of the pipeline, the concept artist illustrates the final form of the creature. Of course, not everything can be conveyed in a single or even multiple drawings, so the modeller must pick up the pieces and interpret, adding his own artistic touch to the concepts. It is critical for the modeller to be able to accurately interpret the concept art and, where necessary, correct or add to the anatomical forms that are being built in 3D. Modellers must understand the underlying structure and muscles that create the masses and planes of the animal.
Equally, the rigger needs to understand the same information to accurately articulate the model: where the joints are, what masses deform and what masses remain rigid. Finally, the animator takes the rig and works within the constraints laid down by the skeleton and controls. If knowledge is lacking in any of these waypoints in the pipeline, then the final result is compromised. 3D imposes more demands than any other medium, because very little information can be left out: we need to know it all.
The task is difficult given the tremendous variation there is in the animal kingdom: from hippopotamus to mouse to dinosaur. The important thing is to study and understand the commonality between them. Once this is understood, the variations become simple to grasp. Likewise, once the basic structures are understood, they can easily be extended to imaginary creatures, grounded in functional anatomy that is learned from the diversity of nature.