When beginning a survey of the major skeletal structures of animals it is useful to begin with the horse, cow, cat, and dog, or the "4 key species." Many animal drawing books suggest beginning with these 4 as it give a broad understanding of animal type and function. Once these 4 are understood the idea is that variations of each becomes easier. For example, once the dog is learned, the wolf, hyena, fox, etc. can be understood as variations of the canine.
Following a discussion of the basic types I began with the hard work of comparing the skeleton of the human, horse, and cat. The skeleton exists is the foundation from which the figure/animal is studied in order to analyze movement, develop three dimensional structure, and interpret anatomy. My personal interest here is in understanding the skeleton and shapes as of course being functional but also as a way to understand each animal as having a unique "design theme." In other words, each animal offers an opportunity to study specialized attributes and how they manifest through a specific design aesthetic.
For example, skeletal changes from the figure to the horse, should be considered in relationship to different evolutionary needs, i.e. what is the subject designed for or what is it's job? What type of environment shaped it? What are it's strengths and limitations? Equating the qualities of form and function not only helps with understanding the inherent design in each but also provide a more generative way of thinking across the 4 "key types" ... and potentially your own creatures.
The demo below compares aspects of the "form language" in select skeletal parts of the human and horse. My hope is that once I understand the skeleton I am able to abstract it to a simple language of shape and form all of which can be imagined as simple manipulations of the design of the figure or spheres, cylinders, and boxes (DaVinci called this process "mental sculpting"). For example, it is possible to see the geometries used to design the horse as influenced heavily by the box and triangle. In a more abstract sense these shapes are effective at communicating feelings of stability or endurance and so match the subject well. In another example, the form language for a cat may emphasize the sphere and triangle which suggest a more fluid yet dynamic (predatory) quality.
Having discussed the basic parts and designs of the skeleton, I build the horse, human, cat, etc., with gesture, tilts and shapes, connections, then into landmarks, perspectives, and anatomy. I think using one process and varying the components within to describe specific animals is an efficient way to learn multiple subjects. I this sense you don't need to learn a new approach for every animal only how to vary the components included in the process.
The front and back 3/4 horse demonstrations views have been broken down into stages. Again, this is the workflow I use when drawing to analyze or learn my subject but it isn't the only approach. You only need to pick up "The Weatherly Guide to Drawing Animals," or "The Art of Animal Drawing" to see a wide diversity of approaches and their benefits.
The sketchbook pages below have been made using the same process.
If you're interested in learning more, remember I'm giving a three day lectures on animal anatomy in Rome, Oct. 21-23 http://www.idea-academy.it/EN/Workshops/36/Animal_Anatomy_for_Creature_and_Character_Design/333