Head shapes

I better post some of the sketches I've been sitting on! I've been thinking about skull shapes for anthros for sometime. Previously I looked at the need for anthro skulls to have a cranial dimension like that of a human, if you're thinking intelligence it seems fitting to exaggerate an animals skull to hold a similar brain size to a humans.

The 2 small intermediate diagrams show the distinction of cranial size (red), 
nose/face area (blue) and jaw (green).

Animal skulls are much more elongated front to back than a human's. Where you'd draw an average human skull as a sphere with a box below for the jaw, for an anthro you're looking more at a ovoid with a box at the front. This is so you can retain the distinct facial features such as those elongated noses and jaws. You can break this idea down further into class (I take class to mean either carnivore, omnivore or herbivore). The main distinction between them being the required jaw size to tackle their specialised foods. As a general idea, jaws tend to get both longer and deeper with herbivores; more muscular action is needed to grind plant matter, so a large bone surface is required, their food is generally in a hard to reach place, hence the long face. For either class, starting with a skull similar to that of a human guarantees you'll retain an adequate brain size.

Taking this a little further the idea of snout length is certainly up to not only the species and the class but also to your own preference. Felines tend to have a much rounder short snout, canines have a more rectangular and thin snout. Length adaptation is up to you. For example, the sketches above are for carnivores, their main principle is that their jaws are thin and sleek with large forward pointing eyes however the length of the snout is undefined.

Jaws are nothing without teeth, and teeth are distinctly specialised for each class. There are a number of other more subtle differences than teeth to think about, especially if you want to be creating expressive characters. Jaw depth i've mentioned, however it's carnivores that tend to have a much larger jaw opening range to catch and eat pray. Useful for expressions showing rage and anger. Due to their large teeth, particularly their canines, carnivores have limited side to side motion which herbivore use to rotate their jaws to grind plant matter. Side to side motions are more or less reserved to show puzzlement or thinking. 

Ahhhhhh a splinter!

Huh?

Lumbar Support

I've gone back to thinking more about spinal curves when it comes to anthros. This is particularly relevant with tough, heavy types and also very relevant when thinking about how a tail would be structured and function on a biped. I think that the fundamental understanding of what can and can't be done with anthros bipeds certainly concerns the lumbar support system.

Part of the lumbar lordosis support

The human S-curve transfers tension and load down into the pelvis via the sacro-iliac joint. If we are going to retain anthro features such as larger skulls, bigger chest and shoulder like that of Minotaurs, the more weight we are applying to the cervical and thoracic vertebrae, ultimately pulling the torso forward as well as the centre of gravity. This is going to make it harder for this S-curve to hold it's mid-line (shown in red). If the mid-line shifts away from the sacro-iliac joint then weight transmission is less efficient, resulting in muscle groups having to bear the torso's load rather than the spine. 


In humans an important deep structure called the thoracolumbar fascia, which are tough multi-directional connective tissues directly attached to the spinous processes of the lumbar vertebrae. Our erector spinae muscles and latissimus dorsi, as well as our core muscles such as the obliques act to pull the thoracic spine (our chest) backwards and downwards, keeping us held upright. The gluteals as I've mentioned in previous posts are under tone to hold the pelvis from tilting forward, keeping us stood upright. These multiple actions ultimately draw the lumbar spine into lordosis like drawing the string on a bow, the lumbar curve is under a great deal of elastic energy, stored in the thoracolumbar fascia.


Understanding the limits of the lumbar curve is important for anthro characters, who are often portrayed as extra massive, with craning necks and heads. The spinal curves may have to adjust to hold this weight and maintain the mid-line, either through hyperlordosis or even kyphosis.

How the sacro-iliac joint and the lumbar curve would be arranged to structure a tail is a relevant question. It would certainly require changes to the configuration of the pelvis as well as considerations on nerve pathways out of the sacrum.

More on the thoracolumbar fascia:

Skull to Neck

As heads get bigger, so does the weight of keeping them upright. Here i'm showing the nuchal ligament as being an important part of keeping a larger head upright.

We need to strike a careful balance with how we expect larger anthro skulls to sit on a biped spine. The cervical vertebrae is the most flexible part of the spine but this comes at a trade-off with strength. Strong yet flexible interspinal ligaments hold the vertebrae from palling apart and in many quadrupeds the nuchal ligament is very important in holding the head and neck from collapsing under it's weight. In humans this tough ligament is less important, our skulls are balanced on the 1st cervical vertebrae, the Atlas, with stability aided by numerous muscles. An anthro skull by contrast would likely be heavier, larger facial features, big jaw. This upsets the balance and we can either reposition the skull on the atlas like a pivot or we recruit ligaments and muscles to help stability. Nuchal ligaments would act like a suspension bridge, pulling from the processes on the thoracic vertebrae to a prominent crest on the part of the Occipital bone of the skull.

What does this mean for character designs: 

consider the weight of your characters heads, this includes big horns and teeth! 

How would the cervical vertebrae curve, is it realistic

Where is the load of the head being distributed

Spinal processes are going to be visible along their backs

How will bigger back muscles such as the trapezius look and how is that head able to flex and move?!

Comparative Skull Proportions

Each skull is divided simply into 3 parts; red - the maxilla and the plains of the 'face'; green - the mandible; blue - the cranial vault; yellow - the Axis (1st cervical vertebra). Each represents to a rough scale the respective size of each skull element in a) human, b) canine and c) equine. Note the cranial vault does not directly represent respective brain size.

I've started with a thought on the sentient issues of anthro' characters. We would expect our characters to the be the singing, dancing types of the average human. So if we take the casual assumption that to have the same level of intelligence means having the same brain size of a human we soon need to adjust the proportions of the skull to accommodate this. Fig 2 indicates  a size of the cranial vault in blue of a human (a) that we'd need to apply to our animal skulls. How then do we balance this with the large jaw and jaw muscles of a herbivore or carnivore? What changes does a larger cranium make to that of the facial plains, particularly the Zygomatric (or cheek bones), the position of the eyes and visual field? We have a number of considerations to make and plenty of permutations dependent on species...