Stuart Sumida Explains the "Five Most Important Anatomical Rules for Animators"

Stuart Sumida

Palaeontologist Stuart Sumida was at Escape Studios last night, demonstrating to our students "The Five Most Important Anatomical Rules for Animators".

Stuart is a world expert on animal anatomy and creature locomotion, widely consulted for his technical expertise on animated feature films like “Spirit”- Stallion of the Cimarron”, "Beauty and the Beast" “Lion King”, "Zootopia" and and “How to Train Your Dragon”.

Who is Stuart Sumida?

Dinosaurs - brought to life by artists

Stuart is a “paleontologist who gets to work with animators” and, while his day job is to teach anatomy to medical students, he also consults on movies for Disney, Pixar and DreamWorks.

Paleontology meets art
Sumida describes palaeontology as a potentially dry subject, brought to life by artists, because the bones of a long dead animal tend not to make sense until an artist makes an image of it, that tells the animal's story.

Science and entertainment
As Stuart puts it: "Science and art go together". The famous T Rex has only one complete surviving skeleton - the rest are copies, or incomplete skeletons.  And the job of bringing the dry bones of the T Rex bones is largely left to artists. The first Jurassic Park movie was "hugely important", because it made dinosaurs feel real for the first time. Animators and scientists are not in opposition - they "should work together".



Entertainment, not documentaries
Dinosaur movies take big liberties. But Jurassic Park is not paleontology, and it’s not a documentary.  Big dinosaurs almost certainly could not rear up on their hind legs as they did in the movie. Their bodies would likely have collapsed under their own weight if they had tried to do this.  So the clip above - says Stuart - couldn't really have happened. But, "we're not making documentaries, we are making entertainment".

The Five Most Important Anatomical Rules for Animators

Rule 1: You are what you eat
Animals are generally designed to eat either meat, or plants (humans are designed to eat both - but mostly plants). The reason you can ride a horse is "because it eats plants". Plants are surrounded by cellulose, which makes them hard to eat and digest. Plant eaters need to eat constantly just to survive, with barrel-shaped bodies to contain their stomachs. Carnivores, by contrast, have short digestive tracts, because their food is much more nutritious. As a result they are much more bendy; cats are bendy "because they can be".  The guts of a horse are four times longer than a carnivore, so they need a rigid backbone to hold up all that gut.  So, what you eat determines your body shape. You can ride a horse because of its straight back.

Animals gaits
Gaits are different too; gallop is different depending on whether you are a carnivore or a herbivore. Herbivores do a "transverse gallop", with a stiff body, while carnivores do a "rotary gallop", with a flexible body (And, note that in a cheetah's run, such as the one below the head doesn't move much - the cat locks its head in place so it can fix its attention on its prey).



Eyes
What you eat even affects where your eyes are located. In carnivores, the eyes are at the front of the head - so they can hunt effectively.  Herbivores tend to have their eyes on the side, to make way for their huge jaws, needed for the endless chewing required to digest all that cellulose.

Herbivore and Carnivore

Lion King
On Lion King, the Disney studio wanted two contrasting comedy characters - Timon and Pumbaa - "a fat guy and a skinny guy", which means, in the animal kingdom "a herbivore and a carnivore". The warthog and the meerkat eat different things, so their body types contrast one another.

Digimorph.org
Stuart pointed out very useful online resource, paid for by the US taxpayer: www.digimorph.org is a great resource for scans of skulls and skeletons, all online. Digimorph have thousands of skulls and skeletons available for free download.

Rule 2 Size matters
The bigger you are, “the more you are affected by gravity”. Big animals “have to keep their limbs straight just in order to stay upright”. And galloping is difficult if you are big. A giraffe is “about as big as you can get and still gallop”. Can an elephant gallop?



George of the Jungle
Bigger animals like elephants “cannot gallop – they are just too big”. So when elephants want to run, they instead “do a really fast walk”. On George of the Jungle, the elephant "thought he was a dog", so it had to be animated to behave like a dog, even though it was an elephant. The CG team first rigged it like an elephant, but it didn’t work, so they had to “rig it like a dog”, to make the animation work. This meant, of course, breaking some rules. The resulting animation looks funny, because a real elephant can't run. Is it accurate? No. But then, "we're not making documentaries".

Size matters in locomotion
When it comes to animal locomotion, “size matters”. Small animals are “much more bendy”. For example, “they can bound”. The bound “is is a three beat gait – hind, front - front.” Mice do this often.  Stuart worked on this for Pixar on Ratatouille. Rats are small, and animals have very big thigh muscles - all the power comes from the back legs.

Stitch - proportions of a human baby

Rule 3 Age matters: big heads and small bodies are cute
On Lilo and Stitch, Stitch is cute because he has the proportions of a baby. Pooh bear has a toddler's proportions, and piglet even "wears a onesie".  

We are hard wired by evolution to think babies are cute; it's why we love our children. Babies have big heads and small bodies; this is why we like puppies and kittens.  Look at Mickey Mouse over the years; he has evolved from a mouse into a baby in terms of his proportions.

On Lion King, Rafiki represents age and wisdom; he has wrinkles and a long face; he is the wise sage, contrasting with the cuteness of baby Simba.

Rule 4 Sex matters
Women have broad hips, because "they need to pass a head through the gap" during childbirth. Men have narrow hips because they only need to "fit a few tubes through the space". Women tend to have long legs and short torsos; men have longer bodies and shorter legs.  So, because women have long legs and wide hips, their "hips tend to swish" when they walk.

We select for these characteristics when we create extreme characters.  You can play with these rules and mess with them. Women characters tend for example, to have longer legs, and shorter torsos than men do. To make your character designs work, you need to understand anatomy.

Rule 5 Skeletons matter
When you build animals and creatures, you need to leave room for muscle and fat on top of the skeleton.

Rule 6  - Creatures and mythical creatures are built out of parts we already know
What's the anatomy of a dragon? The Gronkle was a crocodile and a bumble bee. You need to go and find the original parts that make up the mythical composite, not just copy what other animators have done.

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