Sabertooth Diaries: “Outside in”

Ever since the times of Georges Cuvier, the reconstruction of fossil vertebrates is known as a process that proceeds “from the inside out”, as we first draw the skeleton and then add succesive layers of soft tissue until we finish with the skin and fur. But, as I prepared my reconstructions of sabertooths, I also did the opposite exercise: to draw extant animals “from the outisde in”. What is the point? Well, it is easy to get the wrong mental picture of how the bones of an animal fit inside its body. One may naively imagine that bones are broadly in the center of the mass of soft tissue, but the relationship between the skeleton and the outline of the living animal is more complex, with bone coming quite close to the surface in some particular places (which the classic anatomists knew as “bone points”), while it is hidden under deep layers of flesh in other parts. In order to get used to the correct arrangement of flesh over bone, I did dozens of drawings of modern cats with their skeletons inside. I simply traced the outlines of big cats from photographs (many of them taken at the Madrid zoo), and then using as reference the positions of the “bone points” as illustrated in anatomy manuals, I drew the bones inside the soft tissue “envelope”. After a while the exercise gets easier and more fun -it is relatively simple to pinpoint the ankle, knee or elbow of the animal and place there the corresponding parts of the skeleton (calcaneum, patella, olecranon…) and so on, and then putting the rest of the skeleton in place. And then some things kept surpising me, for instance how far the nasal opening of the skull is behind the external nose of the animal…

Some of these sketches were done almost 20 years ago! Ever since then, I have had the opportunity to make many dissections and CT Scans of big cats, which have allowed me to refine interpretations of bone-to-soft-tissue relationships, but to this day I find that “bone-point” sketching is an enormously useful exercise, and one that you can do with the simplest of tools!

Now some of those old sketches:

First, here is a tiger walking leisurely…

tigre-zoo-1

 

Below, a jaguar…

jaguar-zoo-stuttgart

 

Below, a lioness head in side view. Here, the eyes an ears are essential for inferring the position of the apertures in the skull, while the lower canine is especially useful for drawing the elements of the jaw. I often outlined the masseter muscle in these drawings, to check how the mass of this powerful muscle is partly obscured by the long hairs growing right behind it in many cat species.

 

cabeza-leona

 

And here is a little collection of sketches of lioness heads in different views. Here I also practiced positioning the eyeballs within the eyesockets, and trying to figure out the difference in size between the actual eyeball and the part of the iris that is normally seen between the living animal’s eyelids.

cabezas-felidos

 

In forthcoming posts we will see examples of the opposite procedure -drawing the sabertooths from the inside out. That is when we can apply what we have learned from these simple but useful exercises!

 

Posted on 18/02/2013, in Uncategorized. Bookmark the permalink. 3 Comments.

  1. I tried this with varanids, studying the skulls and particularly nares. learned loads … now all I have to do is make them look as good as yours!

  2. Hello mauricio, the Master of felid reconstructions at work. Great educational contents and sketches. Thank you very much for sharing.

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